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BIO360 Exam 1 (CH 1 - 8)

BIO360 - Animal Physiology Exam 1 (Chapters 1 - 8)
STUDY
PLAY
Which of the following is an important characteristic of lipids?

They can be linked into long chains.

They dissolve in water.

They can be converted to hormones.

They are nonpolar.
They are nonpolar. pg33
What is a substance that can moderate the change in pH of a solution?

An enzyme

A polar compound

A buffer

Peptide
A buffer pg 49
Which compound is hydrophobic?

Potassium ions (K+)

Sugar

Butter

Table salt
Butter
Lemon juice has a pH of about 2.0, compared to a pH of about 1.0 for stomach acid. Therefore, the concentration of H+ in stomach juice is ________ than that of lemon juice.

10 times higher

2 times lower

2 times higher

10 times lower
10 times higher pg48
Define interstitial fluid, indicating if it is inside or outside cells (intracellular or extracellular).

Interstitial fluid is the intracellular fluid found in all cell types.

Interstitial fluid is the extracellular fluid inside the circulatory system.

Interstitial fluid is the intracellular fluid of the blood cells.

Interstitial fluid is extracellular fluid outside the circulatory system and the cells.
Interstitial fluid is extracellular fluid outside the circulatory system and the cells.
Functions of the cell membrane include physical isolation of the cell from its surroundings, regulation of exchange, structural support, and which other function?

Communication between the cell and its environment

Radiation of heat to prevent protein denaturation and cell stress.

Extracting energy from the environment for cell survival

Binding and delivery of oxygen
Communication between the cell and its environment 65
Cell membranes are mainly constructed from ________.

lipids and carbohydrates

lipids and proteins

nucleic acid and proteins

carbohydrates and proteins
lipids and proteins 66
Mitochondria are unique organelles in several ways. They contain a specific genome that allows them to produce their own proteins. They can undergo replication to create more mitochondria within a cell. What other characteristic make mitochondria unique from other organelles?

They have a double wall creating two separate compartments.

Mitochondria store calcium.

Their outer membrane is made up of lipid.

They contain enzymes and proteins.
They have a double wall creating two separate compartments. 71?
Which tissues would likely have cells with the greatest number of gap junctions?

Epidermis

Mucosal layer of the GI tract

Bone

Cardiac muscle
Cardiac muscle 79

***GAP JUNCTIONS ARE USED FOR CELL-CELL COMMUNICATION. These junctions are ideal for cardiac muscle. Cardiac muscle requires a lot of communication because each cell must contract simultaneously each time the heart beats***
Which two fluid compartments make up the extracellular fluid?

Plasma and interstitial fluid

Cytosol and plasma

Intracellular fluid and plasma

Interstitial fluid and intracellular fluid
Plasma and interstitial fluid 65
In a system that includes a ball and a ramp, when would potential energy be greatest?

When the ball comes to rest at the bottom of the ramp

When the ball was at rest at the top of the ramp

When the ball is at its maximal velocity

When the ball first begins to roll down the ramp
When the ball was at rest at the top of the ramp 101
What type of reaction releases energy?

An exergonic reaction

A reversible reaction

An endergonic reaction

A thermodynamic reaction
An exergonic reaction 103
A kinase moves which functional group or molecule?

Amino groups

Phosphate

Hydroxyl

H2O
Phosphate 108
Enzymes ________.

are altered in structure as a result of chemical reactions

allow for chemical reactions to occur, which would otherwise not be possible

increase the rate of chemical reactions

determine the direction of the chemical reaction (i.e., whether molecules are produced or broken down).
increase the rate of chemical reactions 105
What is the definition of "metabolism?"

It is the reaction in an organism that uses energy.

It is the total of all the chemical reactions in an organism.

It is the reaction in an organism that releases energy.

It is the reaction in an organism that takes large molecules and breaks them into smaller units.
It is the total of all the chemical reactions in an organism. 109
What is the simplest way for a human cell to acquire the activation energy necessary for metabolic reactions?

Couple an exergonic reaction with an endergonic reaction.

Allow more water to flow across the cell membrane and use the kinetic energy to drive reactions.

Use the energy in sunlight to drive chemical reactions.

Increase the internal cellular temperature.
Couple an exergonic reaction with an endergonic reaction. 104
During aerobic metabolism of glucose, most ATP is produced during which group of chemical reactions?

Conversion of pyruvate to acetyl CoA

Citric acid cycle

Electron transport (yielding 26-28 molecules of ATP per molecule of glucose)

Glycolysis
Electron transport (yielding 26-28 molecules of ATP per molecule of glucose) 111-115?
Which of the following best describes the function of enzymes?

Enzymes slow down chemical reactions so they don't proceed too fast, thus causing problems.

Enzymes will turn into specific molecules as needed by the body, such as ATP.

Most reactions are due to the addition of a phosphate ion (phosphorylation) to a molecule to create a reaction. The phosphate ions come from enzymes.

Enzymes lower the activation energy level of a chemical reaction, thus making it so the reaction will proceed.
Enzymes lower the activation energy level of a chemical reaction, thus making it so the reaction will proceed. 107
How does the intracellular fluid compartment differ from the extracellular fluid compartment?

Sodium ions are more concentrated inside cells than in the plasma.

Proteins are more concentrated in the interstitial fluid than in cells.

Bicarbonate ions (HCO3 -) are more concentrated inside cells than in either the interstitial fluid or plasma.

Potassium ions are more concentrated inside cells than in the extracellular space.
Potassium ions are more concentrated inside cells than in the extracellular space. 172
(Answers Box #2)
If a swimmer cuts his foot on a seashell while wading in the ocean and bleeds into the seawater, his red blood cells (erythrocytes) will shrink. What does this tell us about seawater?

The seawater is hypotonic to the erythrocytes.

The erythrocyte cell membrane is not permeable to seawater.

The seawater is isotonic to the erythrocytes.

The seawater is hypertonic to the erythrocytes.
The seawater is hypertonic to the erythrocytes. 134
How can a solution be hyperosmotic but hypotonic?

If the concentration of nonpenetrating solutes is less in the solution than in a cell

If the concentration of penetrating solutes is higher in the solution than in a cell

If the total concentration of solutes in the solution is less than in a cell

If the amount of solutes is the same in the cell and solution
If the concentration of nonpenetrating solutes is less in the solution than in a cell 135
What is the mechanism of action of the cystic fibrosis transmembrane conductance regulator (CFTR)?

It allows for the active pumping of chloride from the extracellular fluid to the intracellular fluid.

It allows for the diffusion of sodium across the epithelium of the cell.

It allows for the diffusion of chloride across the epithelium of a cell.

It moves ATP from the inside of the cell to the outside of the cell.
It allows for the diffusion of chloride across the epithelium of a cell.
How is the function of the CFTR altered in someone with cystic fibrosis?

The CFTR channel is absent.

The CFTR functions in reverse.

The CFTR channel does not respond to ATP.

There is excessive functionality of the CFTR channel.
The CFTR channel is absent. Paragraph 3
Why is the thick mucus in Daniel's lungs a sign that he might have cystic fibrosis?

Without the CFTR, mucus cannot be thinned.

The CFTR is needed to produce a thick mucus.

When not working properly, the CFTR pulls liquids out of the mucus causing it to thicken.

none of the above
Without the CFTR, mucus cannot be thinned.
Why would tasting salty sweat on the foreheads of babies lead a midwife to assume that the baby might be afflicted with cystic fibrosis?

The CFTR allows for chloride to leave the sweat and re-enter the cells, creating a hypotonic sweat.

The CFTR channel actively pumps chloride into the lumen when someone is afflicted with cystic fibrosis.

The water in the lumen of the sweat duct is suctioned out by a defective CFTR channel.

When the CFTR is not functioning properly, it pumps an excessive amount of sodium into the lumen of the sweat duct.
The CFTR allows for chloride to leave the sweat and re-enter the cells, creating a hypotonic sweat.
What is the most important distinction between the membrane transporters known as channel proteins and those known as carrier proteins?

Channel proteins transport water-soluble molecules. Carrier proteins transport water-insoluble molecules.

Channel proteins do not require energy, whereas carrier proteins do require energy.

Channel proteins create water-filled passages for small molecules that do not bind to the protein. Carrier proteins transport larger molecules by binding to them.

Channel proteins transport only very small molecules. Carrier proteins transport macromolecules.
Channel proteins create water-filled passages for small molecules that do not bind to the protein. Carrier proteins transport larger molecules by binding to them. 146
What properties must a molecule have to pass through a cell membrane by simple diffusion?

They must be polar and ionic.

They must be small and/or lipophilic.

The temperature must be high enough to increase the speed of the molecule so it has ample force to pass through the membrane.

They must be able to change shape to pass between the lipid molecules of the membrane.
Essentials Figure: An Application of Osmolarity and Tonicity
They must be small and/or lipophilic. 165
Which of the following statements correctly describes the relationship between intracellular fluid (ICF) and extracellular fluid (ECF)?

All of the contents within the ICF are readily exchanged with the contents of the ECF.

Total solute concentration differs in the ECF when compared to the ICF.

The ICF and the ECF are in a chemical equilibrium.

The types of solutes and their distribution between the ICF and ECF are not the same.
The types of solutes and their distribution between the ICF and ECF are not the same. 130
A solution containing:
Which of the following conditions below has the highest osmolarity?

5 mOsm of potassium (K+) and 3 mOsm of sodium (Na+)

3 mOsm of sodium (Na+) and 4 mOsm of chloride (Cl-)

2 mOsm of chloride (Cl-)

7 mOsm of sodium (Na+)
5 mOsm of potassium (K+) and 3 mOsm of sodium (Na+)
Solute/Volume = Concentration

You have prepared a beaker containing two membranes that are permeable only to water. This beaker has three separate compartments each containing the following osmolarities:How would you describe the osmolarity of compartment A relative to compartment B?

A. 10 Osmol/L
B. 13 Osmol/L
C. 7 Osmol/L

Compartment A is hyposomotic to compartment B.

Compartment A is isosmotic to compartment B.

Compartment A is hyperosmotic to compartment B.
Compartment A is hyposomotic to compartment B.
Using the same scenario as Part E, how would you describe the osmolarity of compartment B relative to compartment C?
A. 10 Osmol/L
B. 13 Osmol/L
C. 7 Osmol/L.

Compartment B is hyposomotic to compartment C.

Compartment B is isosmotic to compartment C.

Compartment B is hyperosmotic to compartment C.
Compartment B is hyperosmotic to compartment C.
You have a total body concentration of 900 mosmol dissolved in 3 liters of solution. If you added 0.5 liters of a solution with 150 mosmol of NaCl to the body, what would the new total body concentration be?

450 mOsM

300 mOsM

350 mOsM

700 mOsM
300 mOsM

The Breakdown:

900mosmol / 3L = 300mOsM

150 mosmol / 0.5L = 300mOsM
Channel proteins that can be opened or closed are called ____ channels.

receptor-mediated

carrier

Gated

signal
Gated 147
Membrane receptors are involved in various types of cell signaling. Some membrane receptors function as _____ channels.

chemically gated

mechanically gated

voltage-gated

open
chemically gated
Cell membranes are primarily made of _____ molecules.

cholesterol

Phospholipid

carbohydrate

protein
Phospholipid
What type of membrane transporter would be activated by an action potential?

A voltage-gated channel

A chemically-gated channel

A carrier protein

An open channel
A voltage-gated channel
What will happen to the cells of a patient who is provided with an intravenous solution that is isosmotic to intracellular fluids?

The question cannot be answered with certainty without knowing the identity of the solutes present in the IV solution.

The cells will shrink, because isosmotic solutions are hypertonic.

The cells will retain their normal shape, because isosmotic solutions result in no net change in water concentration.

The cells will swell, because isosmotic solutions are hypotonic.
The question cannot be answered with certainty without knowing the identity of the solutes present in the IV solution.
The membrane potential of most cells ________.

determined primarily by sodium

results in a net negative electrical charge in the body

is negative, except when there is a change in membrane permeability to ions.

is negative at all times
is negative, except when there is a change in membrane permeability to ions.
What will occur if solution A (500ml solution containing 400mosmol/L nonpenetrating solute) is separated by a biological membrane from solution B (4L solution containing 600mosmol/L nonpenetrating solute)?

The volume of B will increase.

The volume of A will increase.

There will be no net volume change.

Solute will flow from solution B to solution A.
The volume of B will increase.
Which type of membrane transport generally requires that the transported molecule dissolve in the lipid membrane?

Phagocytosis

Active transport

Facilitated diffusion

Simple diffusion
Simple diffusion
The permeability of a membrane to a particular molecule is related to two variables. Which two variables is it related to and what is the relationship?

It is directly proportional to both lipid solubility and molecular speed.

It is indirectly proportional to both molecular size and shape.

It is indirectly proportional to the square of the diffusion distance and directly proportional to temperature.

It is directly proportional to lipid solubility and inversely proportional to the size of the molecule.
It is directly proportional to lipid solubility and inversely proportional to the size of the molecule.
Which membrane proteins bind ligands and trigger another membrane event?

Receptors

Structural proteins

Transporters

Enzymes
Receptors 156
Where is most of the water in the body located?

Interstitial fluid

Intracellular fluid

Lumen of the digestive and urinary tracts

Plasma
Intracellular fluid 132
Which of the following statements makes an accurate distinction between type 1 and type 2 diabetes?

Both are characterized by an inability to make insulin.

Type 1 diabetes is characterized by high levels of insulin while type 2 diabetes is characterized by low insulin levels.

Type 1 diabetes occurs when cells of the pancreas stop making insulin while type 2 diabetes occurs when the cells are no longer sensitive to insulin.

Both are characterized by normal levels of insulin, but the cells of the body are no longer responsive to the hormone.
Type 1 diabetes occurs when cells of the pancreas stop making insulin while type 2 diabetes occurs when the cells are no longer sensitive to insulin.
If you give a patient who recently developed diabetes a shot of insulin and blood glucose levels do not change, what type of diabetes does he or she most likely have?

type 2

type 1

It is possible that they could have either.

There is not enough information to tell.
type 2
Is Marvin's high blood glucose level the direct cause for concern expressed by the nurse?

Yes. The body should never have a high level of glucose in the blood.

No. Blood glucose levels are always high in the body and should therefore not be a cause for concern.

No. Blood glucose normally spikes after a meal; it is the fact that it is high under a fasted state that suggests a problem with homeostatic controls.

Yes. High glucose levels are thought to be toxic to all cells of the body.
No. Blood glucose normally spikes after a meal; it is the fact that it is high under a fasted state that suggests a problem with homeostatic controls.
If glucose levels are low, how would you predict activation of the beta cell and insulin release to change?

increase; decrease

decrease; increase

decrease; decrease

increase; increase
decrease; decrease
A given hormone affects ________.

only specific target cells, because nontarget cells lack the appropriate receptors

all cells in the body, but different types of cells produce different responses to the hormone

all cells in the body, because hormones are secreted into blood, which is then transported everywhere

only specific target cells, because hormones are delivered only to those cells
only specific target cells, because nontarget cells lack the appropriate receptors
Extracellular signal molecules are also called

neurotransmitters.

ligands.

receptors.

hormones.
ligands.
Conversion of an extracellular signal into an intracellular one is called

signal transduction.

transmogrification.

translation.

transcription.
signal transduction.
Amplifier enzymes produce

kinases.

second messengers.

phosphorylated proteins.

ATP.
second messengers.
Administration of ibuprofen can decrease pain. Why would this COX-2 inhibitor have this effect?

It blocks production of prostaglandins.

It enhances the production of thromboxanes.

It would inhibit lipoxygenase activity.

It blocks production of the leukotrienes.
It blocks production of prostaglandins.
What are Prostaglandins?
Eicosanoid family. Molecules that regulate physiological systems.
The neurotransmitter norepinephrine ________.

causes some blood vessels to dilate and others to constrict, because different vessels have different receptors for norepinephrine

has effects that are opposite those of the neurohormone epinephrine

affects all blood vessels in the same way, because the response of a target is specific for the neurotransmitter

affects all blood vessels in the same way, because all blood vessels have only one type of norepinephrine receptor
causes some blood vessels to dilate and others to constrict, because different vessels have different receptors for norepinephrine
Which of the following is NOT a means by which cell signal pathways are normally halted?

The signal is halted by the binding of an inactivator molecule to the signal molecule.

The extracellular signal molecule may be transported away from the receptor.

The signal molecule may be pumped out of the cell or into storage.

The extracellular signal molecule may be degraded.
The signal is halted by the binding of an inactivator molecule to the signal molecule.
Alpha-adrenergic receptors have a higher affinity for norepinephrine than for epinephrine. Beta-adrenergic receptors have a higher affinity for epinephrine than for norepinephrine. Which concept about receptor function do these statements reflect?

Specificity

Amplification

Up-regulation

Antagonists
Specificity
Which of the following is the best example of an antagonist?

Atenolol is a drug that binds to β1-adrenergic receptors reducing blood pressure.

Epinephrine and norepinephrine each bind to α- and β-adrenergic receptors, but with different affinities.

Glucagon binds the glucagon receptor (a G-protein-coupled receptor) and causes the release of glucose from hepatocytes.

Serotonin binds the 5-HT receptor and activates phospholipase C but not phospholipase A2.
Atenolol is a drug that binds to β1-adrenergic receptors reducing blood pressure
What are the 6 basic components of a reflex pathway?

S.I.I.E.O.R
Sensor
Input Signal
Integrator
Effector
Output Signal
Response
Name the 7 stages of a Reflex Pathway

S.S.A.I.E.E.R
1. Stimulus
2. Sensor
3. Afferent Signal
4. Integrator
5. Efferent Signal
6. Effector
7. Response
Describe the function of an afferent neuron.

to release neurohormones into the circulatory system

to deliver information about the physiological variable to the integrator

to release neurotransmitters onto an organ

to deliver information to the target tissue
to deliver information about the physiological variable to the integrator
A simple endocrine pathway will include which of the following?

endocrine organ

efferent neuron

afferent neuron

sensor

neurotransmitter

circulatory system

classic hormone

neurohormone

brain

target tissue
endocrine organ
classic hormone
target tissue
sensor
Which of the following best describes the role of endocrine organs in both simple and complex reflex pathways?

to function as a sensor and integrator

to deliver information about the stimulus to the brain

to release neurohormones into the circulatory system

to be the target organs
to function as a sensor and integrator
Specialized neurons in the brain respond to changes in blood osmolarity (solute concentration). When blood osmolairty strays outside of homeostatic range, these neurons release a neurotransmitter that acts upon neurons in the posterior pituitary. When stimulated, the neurons in the posterior pituitary will release a different chemical that will travel via the circulatory system to the kidneys. How would you classify this type of simple reflex?

simple endocrine

simple neural

neurohormone

complex neuroendocrine
neurohormone
In order to prevent damage due to overstretching, skeletal muscles contain specialized sensors. As a muscle stretches, information from these sensors is sent via afferent neurons to the spinal cord where the information is integrated. After integration is complete, an output signal is sent via efferent neurons to the muscle, preventing it from being stretched further. This is an example of what type of reflex pathway?

simple endocrine

simple neural

complex neuroendocrine

neurohormone
simple neural
Arrange in order:

1. Gastrin stimulates parietal cell
2. Parietal cell releases HCL
3. Effernt neurons stimulate the G cell
4. Meal containing protein enters the stomach
5. G-cell releases gastrin into circulation
6. Afferent Neurons send info to nervous system in gut lining
4, 6, 3, 5, 1, 2
Identify the role of the G cell in the gut lining.

integrator

generates response

sensor

target organ
integrator
In the sequence of events mapped out in Part I, what is response?

release of gastrin from the G cell

delivery of sensory information to the nervous system of the gut

entry of food containing protein into the stomach

release of hydrochloric acid by the parietal cell
release of hydrochloric acid by the parietal cell
What is the best example of a first messenger?

Na+, which binds to the Na+/K+ATP pump and is actively transported out of a cell in exchange for K+.

Dystrophin, which associates with costameres to transmit the force of muscle contraction to the extracellular matrix.

Myosin, which binds to actin and causes muscle contraction.

Insulin, which causes the target cell to take up glucose from the blood.
Insulin, which causes the target cell to take up glucose from the blood.
What determines which cells act as targets for endocrine signals?

Those with receptors specific for the signaling molecule.

Those in the same area as the cells that release the hormone.

Those cells that are derived from the same embryonic tissue as the endocrine organ.

Those with a high density of CAMs.
Those with receptors specific for the signaling molecule.
Which form of cell-to-cell communication uses the direct transfer of electrical and chemical signals?

Contact dependent signaling

Autocrine signaling

Gap junction signaling

Endocrine signaling
Gap junction signaling
The most rapid intracellular responses to signals result from activation of receptors that are also ________.

second messengers

ion channels

amplifiers

enzymes
ion channels
Which gas is also a paracrine signaling molecule?

Nitrous oxide

Sulphur dioxide

Carbon dioxide

Nitric oxide
Nitric oxide
Compared to endocrine reflexes, neural reflexes ________.

respond rapidly and are longer-lasting

respond slowly and are very brief

respond slowly, but are longer-lasting

respond rapidly, but are very brief
respond rapidly, but are very brief
Which molecule of the GPCR-adenylyl cyclase signal transduction system phosphorylates proteins to create the cellular response?

Inositol triphosphate

Protein kinase C

Protein kinase A

Phosphatase
Protein kinase A
The hypothalamus senses the temperature of the blood via thermoreceptors. When blood temperature begins to drop, the hypothalamus releases a hormone, TRH, that stimulates the release of TSH from the anterior pituitary gland. TSH causes the thyroid gland to release thyroid hormone (TH). TH causes an increase in body temperature, which causes the hypothalamus to stop releasing TRH. In this reflex response loop, which tissue acts as the integrating center?

The hypothalamus

Thermoreceptors

The thyroid gland

The anterior pituitary
The hypothalamus
Active transport of molecules across membranes requires ATP because ________.

the molecules are moved against the concentration gradient (uphill)

more than one molecule is transported at a time

the transport protein moves or has moving gates

the transported molecules are not soluble in the lipid membrane
the molecules are moved against the concentration gradient (uphill)
The time required for molecules in a solution to move from A to B is proportional to the square of the distance from A to B. What property of diffusion does this principle explain?

Diffusion is rapid over short distances but slow over longer distances.

Diffusion is inversely related to molecular weight and size.

The rate of diffusion depends upon the concentration gradient of the molecule.

Diffusion rate is directly proportional to distance.
Diffusion is rapid over short distances but slow over longer distances.
Ion channels can be opened or closed via three signal transduction mechanisms. Two of them are extracellular signals and second messengers. What is the third mechanism for opening or closing ion channels?

Altered membrane permeability to Ca2+

Electrical signals

Phosphorylation

G protein action
G protein action
Which specific characteristic must a signaling molecule have in order to bind to a cytosolic or nuclear receptor?

It must be a gene activator.

It must be actively transported across the membrane.

It must be lipophilic and able to diffuse across the plasma membrane.


It must contain significant polarity to allow it to associate with its receptor.
It must be lipophilic and able to diffuse across the plasma membrane.
Why is the resting membrane potential (Vm) approximately - 70 mV for most cells?

Most membranes are 40 times more permeable to K+ than to Na+.

Most membranes are 10 times more permeable to Na+ than to K+.

The large concentration of proteins in the interstitial space draws Na+ out of the cell making it negatively charged.

Most cells contain a large concentration of Cl- making them negatively charged.
Most membranes are 40 times more permeable to K+ than to Na+.
The membrane potential of most cells ________.

determined primarily by sodium

is negative at all times

results in a net negative electrical charge in the body

is negative, except when there is a change in membrane permeability to ions
is negative, except when there is a change in membrane permeability to ions
Negative feedback in reflex loops ________.

is "negative" because it opposes homeostasis

is responsible for triggering the response to the stimulus

is rare compared to positive feedback

is common because it promotes homeostasis
is common because it promotes homeostasis
The ion that controls the widest variety of intracellular activities is ________.

chloride

potassium

sodium

calcium
calcium
Signal molecules that degrade most rapidly, resulting in very brief effects, are ________.

hormones

paracrines

ions

gases such as nitric oxide
gases such as nitric oxide
What are the second messengers in the GPCR-phospholipase C signal transduction system?

Ca2+and calmodulin

cAMP and cGMP

Inositol triphosphate and diacylglycerol

ATP and NADH
Inositol triphosphate and diacylglycerol
Which of the following hormones has intracellular receptors?

insulin

epinephrine

Cortisol
Cortisol
What is the mechanism of action of lipid-soluble hormones?

increasing protein kinases

phosphorylation of intracellular proteins

activation of genes, which increases protein synthesis in the cell
activation of genes, which increases protein synthesis in the cell 215
After a lipid-soluble hormone is bound to its intracellular receptor, what does the hormone complex do?

activates a protein kinase

directly alters protein synthesis at the ribosome

acts as a transcription factor and binds to DNA, activating a gene

phosphorylates a protein
acts as a transcription factor and binds to DNA, activating a gene
Which hormone's receptor is always bound to DNA, even when the receptor is empty?

thyroid hormone

insulin

cortisol
thyroid hormone
What keeps intracellular receptors from binding to DNA before a hormone binds to the receptor?

Receptors can't enter the nucleus until the hormone is bound to it.

transcription factors

chaperone proteins
chaperone proteins (chaperonins)
What distinguishes a hormone from other signaling molecules such as cytokines, or paracrine or autocrine signaling molecules?

Hormones are secreted into the bloodstream.

Hormones act when they are in high concentrations.

Hormones are nucleotides while other signals are peptides or lipids.

Hormones bind to receptors on the cell surface.
Hormones are secreted into the bloodstream.

Hormones act when they are in high concentrations.
***No, they act at low [ ]

Hormones are nucleotides while other signals are peptides or lipids.
***NO - most hormones are peptides and proteins

Hormones bind to receptors on the cell surface.
***NO - cortisol is a hormone that has intracellular receptors
A new hormone is discovered. Analysis of its synthesis suggests that it is synthesized on demand and has a long half-life in the bloodstream once it is released. It seems to activate gene transcription in its target cells though no cell surface receptors can be identified. What type of hormone is this most likely to be?

A catecholamine

A thyroid hormone

A peptide

A steroid
A catecholamine
***Catecholamines are neurohormones. They bind to membrane recepts like peptide hormones do. Also have short half-life

A thyroid hormone
***Also behave like steroid hormones but have short half life

A peptide
***Peptide hormones need membrane receptors for entry. Short half-life

A steroid 214
When might negative feedback fail to regulate hormone production, and how would this affect hormone secretion?

A pathology in the endocrine gland could prevent negative feedback from working, resulting in hyposecretion.

Negative feedback may cause down-regulation of receptors in the target cells, resulting in hyposecretion.

A pathology in the endocrine gland could prevent negative feedback from working, resulting in hypersecretion.

Negative feedback may disable the receptors in the target cells, decreasing their response to hormones and causing even more hormone to be secreted.
A pathology in the endocrine gland could prevent negative feedback from working, resulting in hypersecretion.
Norepinephrine and epinephrine cause an increase in heart rate (HR) and stroke volume (SV), which is the amount of blood pumped out during each heart beat, but the effect is enhanced when thyroid hormone (TH) is also present. Oddly, TH has little effect on HR and SV alone. What is the effect of TH on HR and SV called?

Hypersecretion

Cooperation

Synergism

Permissiveness
Permissiveness
Most amine hormones are derived from which source?

Freely circulating amine groups

Tyrosine

Cholesterol

An iodinated peptide
Tyrosine 216
What is the role of the hypothalamus with regard to hormone release and endocrine function?

to release trophic hormones that stimulate the anterior pituitary

to release classic hormones for delivery to the systemic tissues

to release trophic hormones that act on the nervous tissue of the brain

to release classic hormones that inhibit hormone release from the anterior pituitary
to release trophic hormones that stimulate the anterior pituitary 223
Which loss of function would occur if you were to sever the connection between the hypothalamus and the anterior pituitary?

There would be no loss of function.

The portal system would carry tropic hormones from the hypothalamus to the anterior pituitary at an accelerated rate.

The anterior pituitary would not release hormones in response to trophic hormone stimulation.

There would no longer be a release of trophic hormones from the hypothalamus.

All three losses of function listed above would occur if you severed the connection between the hypothalamus and the anterior pituitary.
The anterior pituitary would not release hormones in response to trophic hormone stimulation.
How would you classify the type of chemical released by the posterior pituitary (e.g., classic hormone, neurotransmitter etc.)?

Choose the best answer.

classic hormone

trophic hormone

neurotransmitter

Neurohormone
Neurohormone 221
Which of the following are released by the posterior pituitary?
Select all that apply.

Vasopressin

Oxytocin

prolactin

luteinizing hormone
Vasopressin 219

Oxytocin 219
Where are the neurohormones released by the posterior pituitary produced?

by neuroglia located at the end of the posterior pituitary

in the axon terminal of the neurons that project from the hypothalamus through to the infundibulum

by the endocrine cells located within the posterior pituitary

in the neuronal cell bodies found in the hypothalamus
in the neuronal cell bodies found in the hypothalamus 219
Mrs. Johnson does goes in to visit her doctor because of some health issues that she has been having. One of the many tests that were run on Mrs. Johnson revealed that she had no circulating concentrations of vasopressin. The doctor does a further analysis of her hypothalamus and posterior pituitary to see what might be causing this problem. Predict which of the following might explain Mrs. Johnson's condition.

The cells in the posterior pituitary that release vasopressin are inactive.

The neuronal cell bodies in the hypothalamus are damaged.

The rate of blood flow through the posterior pituitary has increased.

All of the listed answer are possible explanations for the observation.
The neuronal cell bodies in the hypothalamus are damaged.
Which of the following statements regarding the anterior and posterior pituitary is correct?

Anterior pituitary is composed of endocrine tissue while the posterior pituitary is composed of neural tissue.

Both are composed of endocrine tissue.

Anterior pituitary is composed of neural tissue while the posterior pituitary is composed of endocrine tissue.

Both are composed of neural tissue.
Anterior pituitary is composed of endocrine tissue while the posterior pituitary is composed of neural tissue.
What tropic hormone stimulates cortisol from the adrenal gland?

thyroid stimulating hormone (TSH)

growth hormone (GH)

luteinizing hormone (LH) and follicle stimulating hormone (FSH)

adrenocorticotropic hormone (ACTH)
adrenocorticotropic hormone (ACTH)
What is the function of the ventral hypothalamic neurons?

control secretion of thyroid stimulating hormone (TSH)

control secretion of oxytocin

control secretion of antidiuretic hormone (ADH)

control secretion of thyroid hormones
control secretion of thyroid stimulating hormone (TSH)
Insulin-like growth factors (IGFs) are intermediary hormones stimulated by which of the following hormones?

thyroid hormones

GH (growth hormone)

prolactin (PRL)

oxytocin
GH (growth hormone)

**GH stimulates liver to release IGF-1**
Which of the following hormones is regulated by a neuroendocrine ("letdown") reflex?

cortisol

antidiuretic hormone (ADH)

Oxytocin
Oxytocin
Where is antidiuretic hormone (ADH), also known as vasopressin, synthesized?

posterior pituitary

Hypothalamus

kidney

anterior pituitary
Hypothalamus
What is the most important regulatory factor controlling the circulating levels of thyroid hormone?

negative feedback

thyroid-stimulating hormone (TSH)

thyrotropin-releasing hormone (TRH)

a circadian rhythm of release
negative feedback
If the release of thyroid hormone (TH) was regulated by a long-loop negative feedback system, where would the target cells be located to which TH would bind to inhibit the pathway?

The posterior pituitary

The hypothalamus

The anterior pituitary

The thyroid gland
The hypothalamus
What type of hormones bind to receptors located on the cell membrane?

lipid-soluble hormones, such as thyroid hormones and cortisol

water-soluble hormones, such as insulin and epinephrine
water-soluble hormones, such as insulin and epinephrine
Which intracellular substance degrades cAMP, thus inactivating the response to a hormone?

Phosphodiesterase

protein kinase C

phospholipase C

adenylate cyclase
Phosphodiesterase
Growth factor hormones, such as insulin, bind to which type of receptor?

G proteins

tyrosine kinase receptors

intracellular receptors
tyrosine kinase receptors
Which is the correct order of events for hormones activating Gs proteins?

activation of G protein, binding of GTP, activation of adenylate cyclase, conversion of ATP to cAMP

activation of G protein, binding of GTP, activation of phospholipase C, activation of DAG and IP3

activation of a G protein, tyrosine kinase receptor, phosphorylation of intracellular proteins
activation of G protein, binding of GTP, activation of adenylate cyclase, conversion of ATP to cAMP
Which second messenger causes the release of calcium from the endoplasmic reticulum?

tyrosine kinase

IP3

cAMP

DAG
IP3
Which of the following adrenergic receptors increase cAMP levels?

β receptors

α1 receptors

α2 receptors
β receptors
The membrane potential of most cells ________.

is negative at all times

determined primarily by sodium

results in a net negative electrical charge in the body

is negative, except when there is a change in membrane permeability to ions
is negative, except when there is a change in membrane permeability to ions
Why is the resting membrane potential (Vm) approximately - 70 mV for most cells?

Most membranes are 10 times more permeable to Na+ than to K+.

The large concentration of proteins in the interstitial space draws Na+ out of the cell making it negatively charged.

Most cells contain a large concentration of Cl- making them negatively charged.

Most membranes are 40 times more permeable to K+ than to Na+.
Most membranes are 40 times more permeable to K+ than to Na+.
The sympathetic and parasympathetic nervous systems are divisions of which system?

Somatic motor nervous system

Sensory nervous system

Central nervous system

Autonomic nervous system
Autonomic nervous system
The part of the neuron that receives most of the incoming signals is the ________.

dendrite

cell body

soma

axon
dendrite
Which glial cell produces myelin in the central nervous system?

Oligodendrocytes

Ependymal cells

Astrocytes

Schwann cells
Oligodendrocytes
Ions are unequally distributed across the plasma membrane of all cells. This ion distribution creates an electrical potential difference across the membrane. What is the name given to this potential difference?

Resting membrane potential (RMP)

Action potential

Positive membrane potential

Threshold potential
Resting membrane potential (RMP)
Sodium and potassium ions can diffuse across the plasma membranes of all cells because of the presence of what type of channel?

Voltage-gated channels

Sodium-potassium ATPases

Ligand-gated channels

Leak channels
Leak channels
On average, the resting membrane potential is -70 mV. What does the sign and magnitude of this value tell you?

The outside surface of the plasma membrane is much more negatively charged than the inside surface.

The inside surface of the plasma membrane is much more positively charged than the inside surface.

The inside surface of the plasma membrane is much more negatively charged than the outside surface.

There is no electrical potential difference between the inside and the outside surfaces of the plasma membrane.
The inside surface of the plasma membrane is much more negatively charged than the outside surface.
The plasma membrane is much more permeable to K+ than to Na+. Why?

There are many more K+ leak channels than Na+ leak channels in the plasma membrane.

Ligand-gated cation channels favor a greater influx of Na+ than K+.

The Na+-K+ pumps transport more K+ into cells than Na+ out of cells.

There are many more voltage-gated K+ channels than voltage-gated Na+ channels.
There are many more K+ leak channels than Na+ leak channels in the plasma membrane.
The resting membrane potential depends on two factors that influence the magnitude and direction of Na+ and K+ diffusion across the plasma membrane. Identify these two factors.

The presence of a resting membrane potential and leak channels

The presence of concentration gradients and leak channels

The presence of concentration gradients and Na+-K+ pumps

The presence of concentration gradients and voltage-gated channels
The presence of concentration gradients and leak channels
What prevents the Na+ and K+ gradients from dissipating?

H+-K+ ATPase

Na+ cotransporter

Na+-K+ ATPase

Na+ and K+ leaks
Na+-K+ ATPase
The membranes of neurons at rest are very permeable to _____ but only slightly permeable to _____.

Na+; K+

K+; Na+

K+; Cl-

Na+; Cl-
K+; Na+
During depolarization, which gradient(s) move(s) Na+ into the cell?

only the chemical gradient

only the electrical gradient

both the electrical and chemical gradients

Na+ does not move into the cell. Na+ moves out of the cell.
both the electrical and chemical gradients
What is the value for the resting membrane potential for most neurons?

-90 mV

+30 mV

-70 mV
-70 mV
The Na+-K+ pump actively transports both sodium and potassium ions across the membrane to compensate for their constant leakage. In which direction is each ion pumped?

K+ is pumped out of the cell and Na+ is pumped into the cell.

Both Na+ and K+ are pumped into the cell.

Both Na+ and K+ are pumped out of the cell.

Na+ is pumped out of the cell and K+ is pumped into the cell.
Na+ is pumped out of the cell and K+ is pumped into the cell.
The concentrations of which two ions are highest outside the cell.

Na+ and A- (negatively charged proteins)

K+ and Cl-

K+ and A- (negatively charged proteins)

Na+ and Cl-
Na+ and Cl-
Which of the following neurons or groups of neurons are NOT considered to be a part of the efferent pathway?

somatic motor
sensory
parasympathetic
sympathetic
sensory
The part of the neuron that receives most of the incoming signals is the ________.

dendrite
cell body
soma
axon
dendrite
What did Dr. McKhann observe in the children in Beijing and why did this observation lead him to question the original diagnosis of Guillain-Barré syndrome?
Hint 1.
Think about both efferent and afferent pathways.

Children were not able to move but they did have sensory function.

Children did not have sensory or motor function.

Children were able to move around but they did not have sensory function.
Children were not able to move but they did have sensory function.
Why would the conduction velocity of a neuron be used to diagnose demyelinating diseases?
Hint 1.
Myelin surrounds the axon of large somatic motor neurons.

In a demyelinating disease, myelin production increases, which leads to an increase in conduction velocity.

In a demyelination disease, myelin is degraded, which will increase conduction velocity.

In a demyelinating disease, myelin production increases, which leads to a reduction in conduction velocity.

In a demyelination disease, myelin is degraded, which will decrease conduction velocity.
In a demyelination disease, myelin is degraded, which will decrease conduction velocity.
If the children from Beijing did in fact have a demyelinating disease, what would have been the result of Dr. McKhann's conduction velocity test?
Hint 1.
Demyelination will cause a loss of myelin.

increased conduction velocity
decreased conduction velocity
no change in conduction velocity
decreased conduction velocity
Why is the diminished strength of the action potential observed by Dr. McKhann a problem with axons and not myelination?
Hint 1.
Axons propagate action potentials to their targets.

There is no known link between the axon and the action potential.

Because the axonal membrane contains the ion channels necessary to conduct the action potential.

Because the axon contains synaptic vesicles that quickly travel down to their target tissue.

Because the axon diameter determines conduction velocity.
Because the axonal membrane contains the ion channels necessary to conduct the action potential.
What would happen to the membrane potential if a cell suddenly becomes more permeable to Na+?

Hyperpolarize
It would reverse polarity.
Repolarize
Depolarize
Depolarize
What happens if a graded stimulus is of sufficient strength to reach threshold at the trigger zone?

An action potential occurs.

The membrane is hyperpolarized.

The cell becomes more permeable to Cl-.

The graded stimulus moves through the cell more quickly.
An action potential occurs.
Which two properties determine the conduction velocity in a mammalian neuron?

The leak resistance of the membrane and myelination

Axon diameter and the leak resistance of the membrane

The voltage-gated K+ ion channel concentration and axon diameter.

Myelination and voltage-gated Na+ channel concentration
Axon diameter and the leak resistance of the membrane
Which type of receptor would bind acetylcholine and be found in skeletal muscle?

ß-adrenergic
NMDA receptors
Nicotinic cholinergic
Muscarinic cholinergic
Nicotinic cholinergic
Which of the following would NOT cause the membrane potential to change from -70 mV to +30 mV?

Sodium ions entering the cell.
Calcium ions entering the cell.
Chloride ions leaving the cell.
Potassium ions leaving the cell.
Potassium ions leaving the cell.
Where do most action potentials originate?

Hint 1. Parts of a neuron
Most input to a neuron is to the cell body and dendrites. If a neuron is excited to threshold, an action potential will be generated in the first part of the axon. Identify this part.

Axon terminal
Nodes of Ranvier
Initial segment
Cell body
Initial segment
What opens first in response to a threshold stimulus?

Hint 1. Voltage-gated channels
Action potentials occur in areas of the plasma membrane that are densely populated with voltage-gated, or voltage-sensitive, ion channels. Which type of voltage-gated channel is the most rapid to open in response to a threshold stimulus?

Voltage-gated K+ channels
Ligand-gated cation channels
Ligand-gated Cl- channels
Voltage-gated Na+ channels
Voltage-gated Na+ channels
What characterizes depolarization, the first phase of the action potential?
Hint 1. Resting membrane potential
A resting membrane potential (RMP) is exhibited by all cells, and it is caused by an unequal distribution of ions across the plasma membrane. To measure the RMP, a reference electrode is placed near the outside surface of the plasma membrane and a recording electrode is placed near the inside surface. The recorded value is always negative. Thus, the inside surface of the plasma membrane is polarized to a negative value at rest.

The membrane potential changes to a less negative (but not a positive) value.

The membrane potential changes from a negative value to a positive value.

The membrane potential reaches a threshold value and returns to the resting state.

The membrane potential changes to a much more negative value.
The membrane potential changes from a negative value to a positive value.
What characterizes repolarization, the second phase of the action potential?

Once the membrane depolarizes to a threshold value of approximately -55 mV, it repolarizes to its resting value of -70 mV.

As the membrane repolarizes to a negative value, it goes beyond the resting state to a value of -80 mV.

Before the membrane has a chance to reach a positive voltage, it repolarizes to its negative resting value of approximately -70 mV.

Once the membrane depolarizes to a peak value of +30 mV, it repolarizes to its negative resting value of -70 mV.
Once the membrane depolarizes to a peak value of +30 mV, it repolarizes to its negative resting value of -70 mV.

Hint 1. Resting membrane potential
A resting membrane potential (RMP) is exhibited by all cells, and it is caused by an unequal distribution of ions across the plasma membrane. To measure the RMP, a reference electrode is placed near the outside surface of the plasma membrane and a recording electrode is placed near the inside surface. The recorded value is always negative. Thus, the inside surface of the plasma membrane is polarized to a negative value at rest.
What event triggers the generation of an action potential?

The membrane potential must depolarize from the resting voltage of -70 mV to its peak value of +30 mV.

The membrane potential must hyperpolarize from the resting voltage of -70 mV to the more negative value of -80 mV.

The membrane potential must depolarize from the resting voltage of -70 mV to a threshold value of -55 mV.

The membrane potential must return to its resting value of -70 mV from the hyperpolarized value of -80 mV.
The membrane potential must depolarize from the resting voltage of -70 mV to a threshold value of -55 mV.

Hint 1. Voltage-gated channels
Action potentials occur in areas of the plasma membrane that are densely populated with voltage-gated, or voltage-sensitive, ion channels. This type of channel opens in response to voltage change.
What is the first change to occur in response to a threshold stimulus?


Voltage-gated Ca2+ channels change shape, and their activation gates open.

Voltage-gated K+ channels change shape, and their activation gates open.

Voltage-gated Na+ channels change shape, and their inactivation gates close.

Voltage-gated Na+ channels change shape, and their activation gates open.

Correct
Yes! The activation gates of voltage-gated Na+ channels open very rapidly in response to threshold stimuli. The activation gates of voltage-gated K+ channels are comparatively slow to open.
Voltage-gated Na+ channels change shape, and their activation gates open.

Correct
Yes! The activation gates of voltage-gated Na+ channels open very rapidly in response to threshold stimuli. The activation gates of voltage-gated K+ channels are comparatively slow to open.

Hint 1. Voltage-gated channels
Action potentials occur in areas of the plasma membrane that are densely populated with voltage-gated, or voltage-sensitive, ion channels. Threshold stimuli cause conformational changes that open these channels.
The sympathetic and parasympathetic nervous systems are divisions of which system?

Central nervous system
Somatic motor nervous system
Sensory nervous system
Autonomic nervous system
Autonomic nervous system
Most neurons have at least two processes extending from the soma, or cell body. Which type of neuron only has one process extending from the cell body?

An efferent neuron
A pseudounipolar neuron
An interneuron
A unipolar neuron
A pseudounipolar neuron
Which glial cell produces myelin in the central nervous system?

Schwann cells
Ependymal cells
Oligodendrocytes
Astrocytes
Oligodendrocytes
Which of the following statements best describes the concept of permeability?


whether or not a molecule moves across the cell via passive or active mechanisms

the surface area of a cell and its relationship to the diffusion of water

the ability of a molecule to cross the cell membrane

the rate at which a molecule crosses the membrane
the ability of a molecule to cross the cell membrane

Hint 1. The plasma membrane
The plasma membrane is defined as a semipermeable membrane. This means that the membrane is permeable to some substances but not others. The chemical nature of the plasma membrane contributes to its selective permeability properties. The hydrophobic tails create a fatty core that prevents hydrophilic molecules and charged molecules from entering the cell. In order for the charged particles or hydrophilic substances to enter, a protein channel is required.
Hint 2. Rate at which substances move across the plasma membrane
To determine the rate at which a substance moves across the plasma membrane, we use Fick's law of diffusion. This law takes into account several different parameters associated with the plasma membrane, concentration gradients and permeability. While permeabilities will affect the rate at which a substance can cross the plasma membrane, it is not the sole parameter to consider.
The two cells below are hypothetical cells with a concentration of 100 mOsm of K+ inside the cells and containing only leak channels for K+ within the membrane. Each cell is placed into a different solution containing different concentrations of K+ in the extracellular fluid. Which of the two cells below has a higher permeability to K+ and why?

A= 300mosmol w/ 3 channels
B= 50 mosmol w/ 5 channels

A and B would have the same amount of permeability.

A, because it has a greater concentration gradient that B.

B, because it has more ion leak channels for K+ than A.

There is not enough information to tell.
B, because it has more ion leak channels for K+ than A.

Hint 1. Ions and the plasma membrane
The plasma membrane is impermeable to ions due to their charges. In order for an ion to cross the plasma membrane, it would have to travel through a pore. These pores are usually formed by transmembrane proteins that are inserted into the plasma membrane. The transmembrane proteins bypass the lipid core of the bilayer, thus allowing the ions to move across the plasma membrane.
Hint 2. Concentration gradients and ion flow
While the concentration gradients are important for the rate of ion flow, they will not change permeability. Imagine a cell that has a very, very large concentration of Cl-- outside of the cell compared to inside the cell. If this cell does not have any ion channels for the Cl-- and is impermeable to the ion, the concentration gradient becomes irrelevant.
Which of the following statements best describes the resting membrane potential?


the differences that exist between excitable cells and nonexcitable cells

a concentration gradient that exists between the intracellular and extracellular fluids

an osmotic pressure difference that exists between the intracellular and extracellular fluids

an electrical gradient that exists between the intracellular and extracellular fluids
an electrical gradient that exists between the intracellular and extracellular fluids

Hint 1. What are excitable versus nonexcitable cells?
Excitable cells are those that are capable of changing their membrane potentials in order to cause the release of a neurotransmitter or contraction of muscle. For this reason, the body's excitable cells are neurons and all types of muscle. Nonexcitable cells are all the cells that do not have the ability to change their membrane potentials in order to provide a change and/or communication.
Hint 2. What does it mean when something has a potential?
A potential occurs when there is a difference between two sides or compartments. There is a potential difference, for example, between the negatively charged side of a water molecule and the positively charged side of the water molecule.
Concentration Gradients

Note:
In order for an ion to passively move across a cell membrane, not only does there have to be a channel for that ion to move, but there has to be a concentration gradient as well. Concentration gradients are a form of potential energy that will allow for an ion to move from an area of its high concentration to an area where its concentration is low.
...
Indicate whether Membrane Potential Becomes More + or -

Increasing [Na+] in ECF
Increasing [K+] in ECF
Inserting more K+ leak channels
Removing Na+ leak hannels
Decreasing [K+] in ECF
Increasing [Na+] in ECF (+)
Increasing [K+] in ECF (+)
Inserting more K+ leak channels (-)
Removing Na+ leak hannels (-)
Decreasing [K+] in ECF (-)
Hint 1. Changing permeability
You can change a cell's permeability to an ion by either inserting more ion channels or opening up channels for a particular ion that is normally closed. This would result in either an increased influx or increased efflux of the ion across the cell membrane.
Hint 2. Changing concentration gradients
Membrane potential can be calculated by using the Goldman-Hodgkin-Katz equation. This equation (see below) takes in to account the concentrations as well as permeabilities of various ions between the extracellular and intracellular fluids.
Hint 1. Changes in permeability
Changes in permeability can occur when a cell opens up more channels associated with a particular ion. This increase in permeability will allow for the diffusion rate of an ion to increase. As long as there is a potential energy in the concentration gradient of the ion, there will be a net movement either into the cell or out of the cell.
Hint 2. Concentrations of Na+ and K+
Na+ is an ion that will be more concentrated in the extracellular fluid, while K+ is an ion that is more concentrated in the intracellular fluid. These differences create concentration gradients for each ion in opposite directions. The electrochemical gradient for Na+ favors movement into the cell, while the electrochemical gradient for K+ favors movement out of the cell.
Hint 1. Rising phase of the action potential
During the rising phase of the action potential, the membrane potential starts to become more positive. This is due to the changing permeability of the cell to Na+. It begins with a stimulus that increases the cell's permeability to Na+ which increases the influx of Na+ into the cell. As Na+ moves in to the cell, the membrane potential fluctuates from --70mV all the way to +30mV.
Hint 2. After-hyperpolarization phase
The after-hyperpolarization phase occurs due to the functionality of the voltage-gated K+ channels. These channels are slow to close, which will result in an excess leakage of K+. This will usually result in a membrane potential that is equal to the equilibrium potential of K+.
Hint 1. Cause and effect of channels, permeability, and ion flow
The opening and closing of ion channels will directly affect the permeability of the cell to that ion. This event must come first in order for permeability to change. Take, for example, a cell that has only one voltage-gated channel for Na+. When that channel is closed, the cell is not permeable to Na+. Once that channel is opened, the cell is now permeable to Na+ and the ion can follow its electrochemical gradient.
Hint 2. What are graded potentials?
Graded potentials are produced when the cell body of a neuron receives a stimulus from either a receptor or another neuron. These stimuli cause changes in the membrane potential of the cell body which then diffuse like ripples in a pond toward the trigger zone of the neuron. Only if the graded potentials add up to a depolarization that reaches or surpasses threshold, will the trigger zone fire and an action potential result.
Hint 1. Changes in Ca2+ permeability
We have not worked at all with changes in Ca2+ permeability but instead have only looked at the effects of Na+ and K+ permeability. The cells found in the heart as well as the axon terminal of neurons rely on the diffusion of Ca2+ for particular functions. The basic concept is the same. Changes in channel functionality cause the changes in permeability which the result in a change in ion diffusion rate.
Hint 2. Shape of the action potential
All action potentials will not look the same. This is due to differences in the types of ion channels present. Although this might be the case, the relationship between the ion channel and the changes in permeability are the same across all cell types and action potential trace shapes.
Why are Na+, K+, and Cl- the only ions considered in the GK equation when calculating resting membrane potential (Vm)?

These are the only ions to which cell membranes are permeable at rest.

These ions bind to receptors that increase the charge on the membrane.

Only these ions have enough charge to influence Vm.

These ions are found in the highest concentrations inside the cell.
These are the only ions to which cell membranes are permeable at rest.
What would happen to a patient's cellular EK+ if a nurse accidentally administered a potassium solution that caused the patient's extracellular potassium ion concentration to rise to 6.01 mM? Assume a body temperature of 37 °C.

It would become positive, 85 mV.

It would rise to -5.2 mV.

It would become less negative, -85 mV.

It would have no effect on the EK+. This is a constant, fixed value.
It would become less negative, -85 mV.
During an action potential, activation of voltage-gated sodium and potassium channels occurs at different rates. What is the effect of this difference on ion flow across an axon membrane?

At first there is no change in ion movement, then sodium ions flow out of the cell followed by potassium ions later.

K+ will flow into the cell first followed by Na+ flowing out of the cell.

First, sodium ions flow into the cell then potassium ions flow into the cell.

Initially, Na+ flows into the cell followed by K+ flowing out of the cell.
Initially, Na+ flows into the cell followed by K+ flowing out of the cell.
In a graded potential, what is the effect of cytoplasmic resistance and current leak?

More K+ is able to enter the cell, off-setting the depolarizing effects of Na+.

Fewer Na+ can cross the membrane in response to the stimulus.

The outer membrane surface becomes more positively charged, causing hyperpolarization.

The strength of the signal inside the cell decreases over distance.
The strength of the signal inside the cell decreases over distance.
Why is an action potential conducted in only one direction, from an axon hillock to an axon terminal?

The channels are progressively easier to open down the length of the axon.

The number of voltage-gated ion channels increases along the length of the axon.

Second messengers activate channels sequentially.

The membrane channels upstream are refractory and cannot open.
The membrane channels upstream are refractory and cannot open.
What is the definition of an ionotropic receptor?

A receptor that acts through a G-protein to activate a second messenger when bound to its ligand.

A receptor that can bind ions as ligands.

A receptor that alters ion flow when it binds with its ligand.

Receptors that are generally made up of clusters of sodium or potassium ions.
A receptor that alters ion flow when it binds with its ligand.
A stronger stimulus to a neuron results in ________.

larger voltage changes in graded potentials and greater frequency of action potentials produced in response

larger voltage changes in the graded potentials, but no changes in action potentials

larger voltage changes in both graded and action potentials

greater frequency of graded potentials and larger voltage changes in the action potentials produced in response
larger voltage changes in graded potentials and greater frequency of action potentials produced in response
Hint 1. Conduction speed
Recall that axons may be myelinated or unmyelinated. The speed of action potential conduction is increased with myelin, as action potentials are regenerated at nodes of Ranvier only. In contrast, action potentials are regenerated at each and every segment of an unmyelinated axon, and the speed of conduction is slowed.
...
What type of conduction takes place in unmyelinated axons?

Synaptic transmission
Saltatory conduction
Electrical conduction
Continuous conduction
Continuous conduction

Yes! An action potential is conducted continuously along an unmyelinated axon from its initial segment to the axon terminals. The term continuous refers to the fact that the action potential is regenerated when voltage-gated Na+ channels open in every consecutive segment of the axon, not at nodes of Ranvier.
An action potential is self-regenerating because __________.

repolarizing currents established by the efflux of Na+ flow down the axon and trigger an action potential at the next segment

depolarizing currents established by the influx of Na+ flow down the axon and trigger an action potential at the next segment

repolarizing currents established by the efflux of K+ flow down the axon and trigger an action potential at the next segment

depolarizing currents established by the influx of K+ flow down the axon and trigger an action potential at the next segment
depolarizing currents established by the influx of Na+ flow down the axon and trigger an action potential at the next segment

Yes! The Na+ diffusing into the axon during the first phase of the action potential creates a depolarizing current that brings the next segment, or node, of the axon to threshold.

Hint 1. Voltage-gated Na+ channels
An action potential is generated when a stimulus opens voltage-gated Na+ channels. Na+ diffuses into the axon, and the plasma membrane depolarizes.
Why does regeneration of the action potential occur in one direction, rather than in two directions?

The inactivation gates of voltage-gated Na+ channels close in the node, or segment, that has just fired an action potential.

The activation gates of voltage-gated K+ channels open in the node, or segment, that has just depolarized.

The activation gates of voltage-gated Na+ channels close in the node, or segment, that has just depolarized.

The inactivation gates of voltage-gated K+ channels close in the node, or segment, that has just fired an action potential.
The inactivation gates of voltage-gated Na+ channels close in the node, or segment, that has just fired an action potential.

Yes! At the peak of the depolarization phase of the action potential, the inactivation gates close. Thus, the voltage-gated Na+ channels become absolutely refractory to another depolarizing stimulus.
Hint 1. Refractoriness and the Voltage-gated Na+ channel.

An action potential is initiated by the opening of voltage-gated Na+ channels. Depolarizing currents established by the influx of Na+ flow in both directions. However, only the node, or segment, located away from the origin of the action potential will fire. The node, or segment, located nearer to the origin of the action potential will not fire because it is refractory to another stimulus. This phenomenon is caused by the behavior of the voltage-gated Na+ channel.
What is the function of the myelin sheath?

The myelin sheath increases the speed of action potential conduction from the initial segment to the axon terminals.

The myelin sheath decreases the speed of action potential conduction from the initial segment to the axon terminals.

The myelin sheath increases the insulation along the entire length of the axon.

The myelin sheath decreases the resistance of the axonal membrane to the flow of charge.
The myelin sheath increases the speed of action potential conduction from the initial segment to the axon terminals.

Yes! The myelin sheath increases the velocity of conduction by two mechanisms. First, myelin insulates the axon, reducing the loss of depolarizing current across the plasma membrane. Second, the myelin insulation allows the voltage across the membrane to change much faster. Because of these two mechanisms, regeneration only needs to happen at the widely spaced nodes of Ranvier, so the action potential appears to jump.

Hint 1. The myelin sheath
The myelin sheath consists of tightly wrapped coils of neuroglial cell membrane. Oligodendrocytes myelinate axons in the CNS, whereas Schwann cells myelinate axons in the PNS.
What changes occur to voltage-gated Na+ and K+ channels at the peak of depolarization?

Inactivation gates of voltage-gated Na+ channels close, while activation gates of voltage-gated K+ channels open.

Inactivation gates of voltage-gated Na+ channels close, while inactivation gates of voltage-gated K+ channels open.

Activation gates of voltage-gated Na+ channels close, while activation gates of voltage-gated K+ channels open.

Activation gates of voltage-gated Na+ channels close, while inactivation gates of voltage-gated K+ channels open.
Inactivation gates of voltage-gated Na+ channels close, while activation gates of voltage-gated K+ channels open.

Correct
Yes! Closing of voltage-gated channels is time dependent. Typically, the inactivation gates of voltage-gated Na+ channels close about a millisecond after the activation gates open. At the same time, the activation gates of voltage-gated K+ channels open.

Hint 1. Voltage-gated channels
Voltage-gated channels open in response to changes in the membrane potential. When the potential reaches threshold, both voltage-gated Na+ and K+ channels will open. Voltage-gated Na+ channels open swiftly, while voltage-gated K+ channels open with a slight delay. Similarly, voltage-gated Na+ channels close rapidly, while voltage-gated K+ channels close rather slowly.
In which type of axon will velocity of action potential conduction be the fastest?

Myelinated axons with the largest diameter

Unmyelinated axons with the largest diameter

Myelinated axons with the smallest diameters

Unmyelinated axons of the shortest length
Myelinated axons with the largest diameter

Correct
Yes! The large diameter facilitates the flow of depolarizing current through the cytoplasm. The myelin sheath insulates the axons and prevents current from leaking across the plasma membrane.

Hint 1. Axons and speed
Two characteristics of the axon influence the speed of conduction: axon diameter and the presence of myelin. Greater diameters offer less resistance to current flow within the cytoplasm. The myelin sheath insulates the plasma membrane, allowing the voltage to change faster and further down the membrane. Both of these characteristics allow depolarizing current to flow farther and faster.
How is an action potential propagated along an axon?

Stimuli from the graded (local) potentials from the soma and dendrites depolarize the entire axon.

An efflux of potassium from the current action potential depolarizes the adjacent area.

An influx of sodium ions from the current action potential depolarizes the adjacent area.
An influx of sodium ions from the current action potential depolarizes the adjacent area.

Yes, the influx of sodium ions depolarizes adjacent areas, causing the membrane to reach threshold and cause an action potential. Thus, the action potential is regenerated at each new area.
Why does the action potential only move away from the cell body?
Hint 1.
What would stop the action potential from going back towards the cell body?

The flow of the sodium ions only goes in one direction—away from the cell body

The areas that have had the action potential are refractory to a new action potential.
The areas that have had the action potential are refractory to a new action potential.

Yes, sodium channels are inactivated in the area that just had the action potential.
The velocity of the action potential is fastest in which of the following axons?

a small unmyelinated axon
a large unmyelinated axon
a small myelinated axon

Correct
Yes, the myelination acts as insulation and the action potential is generated only at the nodes of Ranvier. Propagation along myelinated axons is known as saltatory conduction.
a small myelinated axon

Yes, the myelination acts as insulation and the action potential is generated only at the nodes of Ranvier. Propagation along myelinated axons is known as saltatory conduction.
What factor does not contribute to the rate of transmembrane transport of glucose?

a. the number of glucose transporters in the plasma membrane

b. the ambient temperature

c. the difference in glucose concentration on the two sides of the plasma membrane

d. the amount of ATP available in the cytosol
d. the amount of ATP available in the cytosol
A cell removed from the body and placed in pure water will:

a. shrink due to a net flux of water out of the cell

b. shrink due to a net flux of ions out of the cell

c. expand due to a net flux of water into the cell

d. expand due to a net flux of ions into the cell
c. expand due to a net flux of water into the cell
Net diffusion of CO2 across a plasma membrane requires:
a. no energy at all

b. the kinetic energy contained in CO2 molecules

c. ATP

d. a transport protein
b. the kinetic energy contained in CO2 molecules
Which solution has the greatest osmolarity? Assume complete ionization of salts.

a. 150 millimoles of NaCl in 1.0 L of H2O

b. 150 millimoles of albumin (plasma protein) in 1.0 L of H2O

c. 75 millimoles of NaCl and 75 millimoles of KCl in 1.0 L of H2O

d. 150 millimoles of MgCl2 in 1.0 L of H2O
d. 150 millimoles of MgCl2 in 1.0 L of H2O
The neighbor's dog ran away and was too inexperienced to find water for a couple of days. As she lost water, she became increasingly dehydrated. What's going on physiologically? Dogs don't sweat much, so assume there is no loss of salt via sweat.

a. she is using increasing amounts of ATP to pump H2O from extracellular fluid back into her cells

b. as her blood volume is decreasing, the osmolarity of her plasma is decreasing

c. to compensate for loss of blood volume, more H2O will move by simple diffusion into cells

d. the average size of most cells in much of her body is decreasing as H2O diffuses out of cells via aquaporins
d. the average size of most cells in much of her body is decreasing as H2O diffuses out of cells via aquaporins
The plasma membrane of axon terminals is, of course, composed of an amphipathic lipid bilayer that acts as a barrier to the influx or efflux (flux out of cell) of most molecules. What would be the most pronounced change in K+ movement if the membrane resistance to K+ suddenly decreased?

a. there would be an increase in net influx of K+ across the terminal plasma membrane

b. there would be an increase in net efflux of K+ across the terminal plasma membrane

c. there would be a decrease in net influx of K+ across the terminal plasma membrane

d. there would be a decrease in net efflux of K+ across the terminal plasma membrane
b. there would be an increase in net efflux of K+ across the terminal plasma membrane
Which is most likely to cross a plasma membrane by simple diffusion?

a. fatty acid
b. protein
c. glucose
d. Na+
a. fatty acid
Which of the following comparisons is accurate?
a. primary active transport requires a transport protein but facilitated diffusion does not

b. primary active transport displays saturation with higher concentrations of substrate but facilitated diffusion does not

c. primary active transport requires the hydrolysis of ATP for energy whereas facilitated diffusion requires only the energy stored in a concentration gradient

d. both facilitated diffusion and primary active transport mechanisms are capable of transporting molecules against their concentration gradient

e. all of these are correct
c. primary active transport requires the hydrolysis of ATP for energy whereas facilitated diffusion requires only the energy stored in a concentration gradient
9. Examine the transport process across the plasma membrane in the diagram. What can you conclude?

Line A = linear
Line B = exponential logistic curve

a. line "a" probably represents facilitated diffusion

b. line "b" might represent facilitated diffusion, 1° active transport, or 2° active transport

c. line "b" must represent active transport

d. line "b" must represent facilitated diffusion
b. line "b" might represent facilitated diffusion, 1° active transport, or 2° active transport
Did you know there are no reports of anyone dying of dehydration while running a marathon? On the other hand, a number of people have died from water intoxication after drinking excessive amounts of water during or after a marathon run. Several years ago, Jennifer Strange (mom below) died of water intoxication after drinking gallons of water as part of a radio contest, "Hold Your Wee for a Wii." What is a sound hypothesis to explain why she died?

a. she waited so long to urinate that her bladder burst causing massive homeostatic disturbances

b. the osmotic pressure across the plasma membrane of her neurons was so great that her brain cells and brain swelled to lethal size

c. she diluted her Na+ and/or K+ concentrations sufficiently to disrupt normal signaling in the nervous system

d. the excessive extracellular water extinguished her vital flame

e. both b and c
e. both b and c
Which body fluid compartment has the smallest total volume?

a. plasma
b. intracellular
c. extracellular
d. interstitial
a. plasma
Which of the following is NOT a good example of physiological homeostasis in a strict sense:

a. the hormones insulin and glucagon act together to closely regulate glucose concentrations in our plasma

b. if body temperature drops, we will attempt to restore it by shivering, changing blood flow patterns and/or behavioral modifications

c. our total body concentration of salt (NaCl) is maintained within a relatively narrow range by the kidney

d. euryhaline fish can live in H2O with varying salinities; they are osmoconformers, meaning that their plasma levels of salt vary directly with their external environment
d. euryhaline fish can live in H2O with varying salinities; they are osmoconformers, meaning that their plasma levels of salt vary directly with their external environment
A receptor for a small, non-polar, hormone is likely to be located in the:

a. Plasma membrane
b. Cytoplasm
c. Extracellular matrix
d. Mitochondria
b. Cytoplasm
What would happen to transport via secondary active transporters if a cell were depleted of ATP?

a. Transport would continue for a while until concentration gradients run down

b. Transport would stop immediately

c. Nothing would change because these transporters do not use ATP

d. Transport direction would eventually reverse
a. Transport would continue for a while until concentration gradients run down
In the Na+/K+ ATPase activity cycle, when is the affinity for Na+ highest?

a. When the transporter binding sites are exposed to the cytosol

b. When the transporter binding sites are exposed to the extracellular fluid

c. When GTP binds to the transporter

d. After the ATP is hydrolyzed
a. When the transporter binding sites are exposed to the cytosol
Which of the following would NOT decrease a target cell's sensitivity to a particular hormone?

a. down-regulate the number of hormone receptors

b. decrease the amount of hormone released from endocrine cells

c. receptor phosphorylation leading to desensitization

d. decrease the affinity of the receptor for the hormone
b. decrease the amount of hormone released from endocrine cells
Caffeine is an antagonist at adenosine A1 receptors. When adenosine target cells are repeatedly exposed to the adenosine receptor antagonist, the cells are likely to increase the synthesis of adenosine A1 receptors and insertion in plasma membranes. Which statement about this phenomenon is true?

a. it's an example of receptor upregulation
b. it's an example of receptor downregulation
c. it's an example of signal amplification
d. the cell will become more sensitive to adenosine

e. the cell will become less sensitive to adenosine

f. both a and d
g. both b and c
f. both a and d
Sarah ran the New York City Marathon on an 85° day. She lost 4 liters of fluid during the race, mostly in the form of sweat, some from breathing. Sweat contains H2O and NaCl. During the marathon, she drank 4 liters of pure H2O to replace the H2O she lost. Which of the following is true at the end of the race? (3hr, 15 min)

a. she must have become dehydrated during the marathon so she needs to drink several liters as soon as possible

b. Sarah lost little H2O overall, but the osmolarity of her extracellular fluids was increased

c. she expended a lot ATP during the race to pump H2O back into her cells by primary active transport

d. it would probably be better to drink fluids that contained electrolytes (NaCl particularly) than pure water
d. it would probably be better to drink fluids that contained electrolytes (NaCl particularly) than pure water
What would happen to K+ flux in a typical cell if membrane resistance to K+ flux suddenly decreased?

a. there would be a decrease in net efflux of K+ across the plasma membrane

b. there would be an increase in net efflux of K+ across the plasma membrane

c. there would be an increase in net influx of K+ across the plasma membrane

d. there would be a decrease in net influx of K+ across the plasma membrane
b. there would be an increase in net efflux of K+ across the plasma membrane
What is the final common pathway for nearly all 2nd messenger-mediated intracellular signaling?

a. change in [cAMP]

b. change in phosphorylation state of specific cellular proteins

c. change in gene expression

d. change in the number of receptors in the plasma membrane
b. change in phosphorylation state of specific cellular proteins
Sartans are a class of drugs used to treat hypertension (high blood pressure). Sartans can lower blood pressure by acting as antagonists at Angiotensin II receptors. Predict/explain how sartans can produce vasodilation (increased diameter of blood vessels; this tends to lower blood pressure).

a. sartans bind to and activate Ang II receptors; the activated Ang II receptors then block activation of G proteins

b. sartans bind to Ang II receptors with higher affinity than Ang II; this prevents Ang II from binding to and activating Ang II receptors

c. Angiotensin II must normally cause vasoconstriction (narrowing of blood vessel lumen)

d. Angiotensin II normally cause vasodilation

e. b and c
e. b and c
Take a look at the two cartoons below representing hormone signaling via G protein-coupled receptors. Which statement about the pathways is FALSE?

a. in both cases the activated receptor activates a G protein

b. in both cases the activated G protein dissociates into alpha and Beta Y subunits
c. in both cases the Alpha subunit of the G protein has intrinsic GTPase activity to terminate signaling

d. in both cases a molecule of GTP is bound to the activated Alpha subunit of the G protein

e. in both cases, the membrane-bound enzyme amplifies the signal

f. in both cases, the pathway leads to phosphorylation of specific cellular proteins

g. in both cases, the end result is the production of cAMP
g. in both cases, the end result is the production of cAMP
What kind of cells are Na+/K+ ATPases found in?

a. animal but not plant cells
b. only neurons and muscle cells
c. virtually all cells
d. only neurons
c. virtually all cells
Ions do NOT cross the plasma membrane of cells by which process?

a. simple diffusion
b. voltage-gated ion channels
c. ligand-gated ion channels
d. active transport
e. carrier-mediated transport
a. simple diffusion
Look at this diagram of ligand binding to a receptor. What can you say from looking at this?

(A & B are both logistic exponential curves. A has a slightly higher curve than B.)

a. Ligand A has a higher affinity for the receptor than ligand B does

b. Ligand A has a lower affinity for the receptor than ligand B does

c. There are more binding sites for ligand A than for ligand B

d. Ligand A is an agonist and ligand B is an antagonist.
a. Ligand A has a higher affinity for the receptor than ligand B does
Examine this equation. Which statement is FALSE?

W=RTln [X]outside/[X]inside

a. The energy stored in a concentration gradient depends upon temperature

b. If [X]outside = [X]inside the cell, there is no driving force for diffusion

c. A concentration gradient has the potential to do work without input of additional energy

d. If the [X]inside is greater than [X]outside the cell, there's no energy for diffusion
d. If the [X]inside is greater than [X]outside the cell, there's no energy for diffusion
Death by injection in many states involves administration of a lethal dose of an anesthetic, followed by a lethal dose of a paralyzing agent, followed by a lethal dose of KCl. In the unlikely event that a subject was still alive after the first two injections, the injection of KCl would stop the heart. I wonder why. Assume that the KCl was concentrated enough to produce [K+] in the extracellular fluid of 150 mM. Assume for this question that cardiac muscle cell plasma membranes are permeable only to K+. What would be the Vm of cardiac cells in the subject in the moments before he/she died?

a. + 15 mV
b. 0 mV
c. + 60 mV
d. - 90 mV
e. - 150 mV
b. 0 mV
Which of the following is the major contributor to the membrane potential of kidney cells?

a. K+ diffusion across the plasma membrane into the intracellular fluid

b. K+ efflux through leaky K+ channels into the extracellular fluid

c. pumping K+ out of cells via Na+/K+ ATPase

d. the concentration gradient of plasmomembranium

e. a and c
b. K+ efflux through leaky K+ channels into the extracellular fluid
What conditions are necessary for cells to have a membrane potential (Vm)?

a. the semipermeable plasma membrane must be permeable to an ion

b. the lipid bilayer can separate and store charge across the plasma membrane

c. the concentration of anions is greater inside cells than outside cells

d. cells must be neurons or muscle cells

e. cell membranes must have voltage-gated ion channels

f. a and b

g. all of the above
f. a and b
Which of the following statements about Na+ / K+ ATPases is FALSE?

a. they generate and maintain concentration gradients for K+ and Na+ in all cells

b. the energy stored in Na+ concentration gradients created by Na+ / K+ ATPases is used to transport other solutes against their concentration gradients by secondary active transport

c. running Na+ / K+ ATPases accounts for a lot of the vertebrate energy expenditure to maintain a dynamic disequilibrium of ion concentrations

d. the movement of ions via Na+ / K+ ATPases create the negative resting potential of neurons
d. the movement of ions via Na+ / K+ ATPases create the negative resting potential of neurons
Which of the following is NOT a signaling pathway used by peptides hormone or neurotransmitter receptors? (Some molecules in pathway may not be listed.)

a. activate Gq, phospholipase C, production of IP3 and diacylglycerol, and activation of protein kinase C (PKC)

b. activate Gs, adenylyl cyclase, increased production of cAMP, and activated protein kinase A (PKA)

c. activate Gi, leading to inhibition of adenylyl cyclase activity and decreased cAMP production

d. activate Gs protein, adenylyl cyclase, and phospholipase C with production of cAMP and IP3
d. activate Gs protein, adenylyl cyclase, and phospholipase C with production of cAMP and IP3
How does a single hormone, like epinephrine (EPI), produce different responses in different cells?

a. EPI binds to adrenergic receptors in some cells but binds to G proteins in other cell membranes

b. Binding to different adrenergic receptor subtypes may activate different G proteins in the plasma membranes of different cells

c. EPI may diffuse into some cells and bind to cytosolic receptors, but not other cells

d. EPI acts as an agonist at some adrenergic receptors but an antagonist at others her cells
b. Binding to different adrenergic receptor subtypes may activate different G proteins in the plasma membranes of different cells
At the resting membrane potential for a typical neuron:

a. there is no net diffusion of K+ or Na+

b. there is net diffusion of K+ but no net diffusion of Na+

c. there is a greater driving force for diffusion of K+ than for Na+

d. the plasma membrane is more permeable to K+ than Na+

e. both a and c
d. the plasma membrane is more permeable to K+ than Na+
What differentiates peptide hormones from steroid hormones?

a. Steroid hormones are synthesized 'on demand' but peptide hormones can be stored for release in vesicles.

b. Steroid hormones are made from cholesterol but peptide hormones are made from amino acids.

c. Steroid hormones can probably diffuse across the plasma membrane but peptide hormones definitely cannot.

d. All of the answers are correct

e. Steroid hormone receptors have chaperone proteins but peptide hormone receptors do not
d. All of the answers are correct
Binding of oxytocin to the oxytocin receptor leads activation of Gq and subsequent activation of phospholipase C land production of second messengers. Which mechanism would normally contribute to the termination of oxytocin signaling?

a. phosphodiesterase activity

b. intrinsic GTPase activity of the alpha subunit of Gq

c. inactivation of cAMP-dependent protein kinase A

d. since the binding of OXY to its R is a reversible reaction, OXY will dissociate from R when the extracellular concentration of OXY decreases

e. both b and d
e. both b and d
Oxytocin is:

a. Synthesized in the neurohypothesis (posterior pituitary)

b. Released from the neurohypophysis

c. Released from the anterior pituitary

d. Released in response to oxytocin-releasing hormone

e. Synthesized in the hypothalamus and released from the neurohypophysis
a. Synthesized in the neurohypothesis (posterior pituitary)
Cortisol is:

a. A peptide hormone that binds to receptors in plasma membrane
b. Released from the anterior pituitary gland
c. Released from the adrenal cortex
d. Released from the adrenal medulla
c. Released from the adrenal cortex
Dr O just did a month of treatment with prednisone, a synthetic cortisol-like drug. Prednisone binds to cortisol receptors and pretty much just acts like cortisol....but it's not. When Dr O was taking prednisone:

a. the concentration of corticotropin-releasing hormone (CRH) in his hypothalamic-pituitary blood portal vessels was high

b. the concentration of corticotropin-releasing hormone in his hypothalamic-pituitary blood portal vessels was low

c. the concentration of adrenocorticotropic hormone (ACTH) in his bloodstream was high

d. the concentration of cortisol in his bloodstream was high
b. the concentration of corticotropin-releasing hormone in his hypothalamic-pituitary blood portal vessels was low
Which of the following scenarios would make the resting membrane voltage across the plasma membrane more positive?

a. Up-regulate the number of leaky K+ channels

b. Increase the concentration of K+ on the inside of the cell relative to outside

c. Increase the number of Na+ passive leak channels in the plasma membrane

d. Decrease the ambient temperature
c. Increase the number of Na+ passive leak channels in the plasma membrane
As part of an undergrad research project, Amanda impaled a rat neuron with a intracellular electrode and recorded the membrane potential. You go, girl! She then added drugs to the buffer bathing the cells to block all ion channels except leaky K+ channels. The extracellular buffer contained 5 mM [K+]; assume [K+]inside = 150 mM. Using a technique called voltage clamp, Amanda could hold the membrane potential at whatever voltage he chose. He started the experiment with the Vm at -10 mV and gradually made the Vm more negative in 10 mV steps. At what Vm would K+ begin to flow into the cell instead of out of the cell?

a. around 0 mV
b. around - 60 mV
c. around - 90 mV
d. around - 150 mV
e. won't happen because [K+] is higher inside the cell than outside
c. around - 90 mV
Groups of cells performing related tasks are known as ________.

organisms
organs
organ systems
tissues
tissues
Which is the best example of integration in physiology?

The interaction of nervous and endocrine signals to regulate blood flow to the small intestines

Air is carried into alveoli in the lungs where oxygen can diffuse through the respiratory membrane into the blood.

The association of fond memories with the smells of a favorite meal

The immune system responding to bacteria multiplying in the submucosal layer of the skin
The interaction of nervous and endocrine signals to regulate blood flow to the small intestines
Which of the following is the best example of a mechanistic understanding of a function?

We are self-aware so that we can recognize ourselves and distinguish ourselves from others.

Skeletal muscle cells contract when myosin heads attach to actin filaments and rotate, producing force.

The kidneys produce urine so that waste products, such as uric acid, do not build up in the blood.

Bones are strong so that they can support our body weight and protect delicate organs.
Skeletal muscle cells contract when myosin heads attach to actin filaments and rotate, producing force.
What is a good reason to consider using mapping to learn physiological concepts?

It is easier to memorize things when they are written in a memorable way such as mapping.

Mapping is a way of forcing students to spend time with the material so they will study and learn it.

Creating a map requires thinking about and understanding the relationships between facts.

Mapping improves recall because it requires that students write down facts.
Creating a map requires thinking about and understanding the relationships between facts.
Select the most accurate definition of homeostasis.

The ability of an organism to maintain relatively constant internal conditions despite variability in external conditions.

The ability of an organism to maintain relatively constant internal conditions as long as external conditions remain relatively constant.

The ability of an organism to return to its original home, as exemplified by migrating animals.

The ability of an organism to prevent changes in internal conditions though external conditions may change.
The ability of an organism to maintain relatively constant internal conditions despite variability in external conditions.
What is the primary mechanism allowing a molecule like an enzyme to perform a particular function?

Its specific structure
The need for that function
The color of the molecule
The location of the molecule
Its specific structure
What is the main difference between the concepts of "steady-state" and "equilibrium?"

A steady-state system is dynamic, whereas a system in equilibrium is not.

There is no movement of materials within a steady-state system, but materials move freely in an equilibrium.

A system in equilibrium is also in homeostasis, whereas a steady-state system can never be homeostatic.

Steady-state systems are inherently unstable and will eventually collapse while systems in equilibrium are stable.
A steady-state system is dynamic, whereas a system in equilibrium is not.
Which component of a control system initiates an appropriate response to a stimulus?

Receptor
Stimulation receiver
Integrating center
Response center
Integrating center
What does it mean if an article has been peer reviewed?

The work has been read by an anonymous panel of researchers in a different field than that represented by the article.

The work has been read by an anonymous panel of doctors.

The work has been read by an anonymous panel of people from the general public.

The work has been read by an anonymous panel of scientists qualified to judge the science.
The work has been read by an anonymous panel of scientists qualified to judge the science.
What is a review article and why might it be beneficial for a novice in a subject matter to read?

It is a technical paper based on a single research project; because it is written as a summary paper that can be understood by a novice.

It contains a synopsis of recent research on a particular topic; because it is full of technical language providing a more in-depth understanding of the subject matter.

It contains a synopsis of recent research on a particular topic; because it gives a general summary of several technical papers, making it easier for a novice to
understand.

It is a technical paper based on a single research project; because for an accurate understanding of the topic, one must read about it in as much detail as possible.
It contains a synopsis of recent research on a particular topic; because it gives a general summary of several technical papers, making it easier for a novice to
understand.
Which of the following search combinations would render in the most accurate results if you wanted to know if there was a link between the consumption of high fructose corn
syrup and the incidence of type II diabetes?

high fructose corn syrup
corn syrup AND diabetes
incidence of type II diabetes
high fructose corn syrup AND the incidence of type II diabetes
high fructose corn syrup AND the incidence of type II diabetes
Which of the following websites would be best if you wanted to learn about the effectiveness of hormone replacement therapy on reducing the symptoms associated with
menopause?

www.mayoclinic.com
www.webmd.com
www.estroven.com
www.nlm.nih.gov/medlineplus
www.nlm.nih.gov/medlineplus

You want to obtain information from organizations that are part of the scientific community. These types of websites will contain reliable information intended to educate the
public on the subject matter.
Processes that cannot be predicted simply from understanding the functions of the individual components of the system are known as ________ properties.

gradient
emergent
retrospective
variable
emergent
Hint 1. Cause and effect relationships
When considering a physiological process, we have to be careful with cause and effect. Let's take a non-physiological process for example. If you fill a pot with water and
place it on a burner, the conduction between the hot burner and the pot will heat up the water causing it to boil. If you were to order these events as cause and effect, you
would say that 1. Stove heats up; 2. Heat transferred to pot; 3. Pot heats water. You would not say that the water heats up which then causes the pot to heat up.
Hint 2. Homeostatic regulation
Cause and effect in physiology is made evident when considering changes to a homeostatic variable and how those changes are corrected for. Consider blood pressure
for example. A high blood volume can cause blood pressure to increase. If blood pressure increases, the heart rate will decreased as a result in order to correct for the
initial increase.
Hint 1. Scatter plots
Scatter plots will typically be used if you want to see the effects that one variable has on the other.
Hint 2. Histograms vs. bar graphs
A histogram is a type of bar graph that could tell you how many people in a class received an 85% on exam 1.
Which of the following would best describe the concept of negative feedback as it relates to homeostasis?

A negative feedback response is one where the setpoint is maintained and is not altered.

A negative feedback response demonstrates a fluctuation around a setpoint.

A negative feedback mechanism is a mechanism that will stop a reaction or response once it begins.

A negative feedback response always increases the quantity/concentration/value of a variable.
A negative feedback response demonstrates a fluctuation around a setpoint.
Heating an area of the skin can cause sweat glands in that area to begin producing and releasing sweat. This is an example of what type of control system.

Local control system
Feed-forward control system
Reflex control system
Positive feedback loop control system
Local control system
What is an independent variable?

The value that is measured.
The thing held constant to ensure that the effect is due to the variable of interest and not due to some unanticipated cause.
The thing that is manipulated to test an effect.
A model that is supported by substantial evidence.
The thing that is manipulated to test an effect.