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BIOL 253 Exam 1
Terms in this set (126)
Which of the following transport mechanisms may be utilized to move glucose across cell membranes?
Secondary active transport and facilitated diffusion
Which of the following statements about the Na-K pump is(are) true?
The location of the binding sites on the Na-K pump dictates the direction of solute movement.
Examples of active transport may include __________.
the movement of Na+ ions out of cells and the movement of glucose molecules into intestinal epithelial cells
Which of the following statements about epithelial transport in the intestines is (are) true?
The Na+/K+ ATPase is found only in the basolateral membrane of intestinal epithelial cells and the movement of Na+ ions across the apical membrane of intestinal epithelial cells is dependent on the electrochemical gradient created by the Na+/K+ ATPase.
Which of the following statements is false with regard to primary/secondary active transport?
Substances will always move down their concentration gradient.
If a cell were to become depleted of its ATP, which type of membrane transport would be most directly and immediately affected?
Primary active transport
Energy released by the hydrolysis of ATP is used to move K+ and Na+ across cell membranes. This process is called __________.
primary active transport
Substances that are going to move against their concentration gradient (from low concentration to high concentration) will use which type(s) of membrane transport?
Primary or secondary active transport
In skeletal muscle, the sarcoplasmic reticulum stores a very high concentration of Ca++. When Ca++ is released into the cytosol of muscle to facilitate contraction, it needs to be removed and pumped back into the sarcoplasmic reticulum so that skeletal muscle can return to its relaxed state. The Ca++ is moved from cytosol and pumped back into the sarcoplasmic reticulum where its concentration is much higher. What type of membrane transport does this represent?
Primary active transport
What is similar between facilitated diffusion and primary/secondary active transport? In both forms of transport __________.
a membrane transport protein is involved
Identify which of the following is the correct definition of primary active transport.
It is mediated by a protein that directly uses ATP energy to move a substance against its concentration gradient.
If many solutes are constantly being pumped into or out of cells, why don't the intracellular concentrations of these solutes change?
For any given solute, the rate of active transport in one direction is equal to the passive movement (leak) of the solute in the opposite direction.
Transport processes that can be saturated include __________.
Primary active transport, Secondary active transport, Facilitated diffusion, ion channel proteins
Which of the following will always be true of primary and secondary active transport?
At least one substance will move against its concentration gradient.
Which of the following statements makes an accurate comparison between primary and secondary active transport?
In primary active transport ATP is directly utilized, while in secondary active transport the potential energy of a concentration gradient is utilized.
Transport processes that require an energy source include __________.
primary active transport and secondary active transport
Which of the following molecules would not simply diffuse through cell membranes easily?
Na+ ions and glucose
As the solute concentration of a solution increases, __________.
the water concentration decreases and the osmotic pressure increases
Which of the following types of molecules would be most likely to pass through the plasma membrane by means of simple diffusion?
Oxygen - nonpolar
In order for water to be absorbed by epithelial cells, __________.
aquaporins must be present in the cell membranes and the concentration of impermeable solutes must be higher on the inside of the cell
Which of the following does not require the use of ATP?
In comparing a solution to a fluid in a cell, a hypertonic solution always has __________.
a higher concentration of non-penetrating solutes than that in the cell
Facilitated diffusion differs from simple diffusion in what way(s)?
The rate of facilitated diffusion depends on the number of carriers in the membrane.
The rate of diffusion, or flux, of particles across a membrane is dependent on __________.
All of the listed responses are correct.
Which of the following statements provides an accurate comparison between facilitated diffusion and simple diffusion?
In both facilitated and simple diffusion, substances move down their concentration gradient.
Which of the following statements about facilitated diffusion is (are) true?
The rate of facilitated diffusion is directly dependent on the number of carrier proteins for a solute and the rate of facilitated diffusion is directly dependent on the concentration gradient of the solute across the membrane.
Water toxicity occurs when __________.
extracellular fluids become hypotonic, causing brain cells to swell
In people with diabetes mellitus, glucose is not being transported into cells at the normal rate. This buildup of glucose in the plasma causes the extracellular fluid to become __________.
hypertonic and hyperosmotic
The term simple diffusion can be used to describe the movement of molecules from an area of __________.
higher concentration to areas of lower concentration
An increase in which of the following increases the rate of diffusion of oxygen molecules across pulmonary cell membranes?
Membrane surface area, the oxygen concentration inside the lung, and temperature
Which of the following conditions would lead to the fastest rate of oxygen diffusion into a cell?
a large concentration gradient and a thin membrane
The difference between carrier and channel proteins is that __________.
channel proteins create a continuous passage between intra- and extracellular compartments
The second messenger DAG .
is membrane bound
In contrast to fast ligand-gated channels, slow ligand-gated channels .
are regulated by G proteins
The cellular response to the second messenger cAMP can be inhibited by activating ________.
The interaction between chemical messengers and their receptors is similar to the interaction between .
substrates and enzymes
Which of the following statements describes a characteristic of G proteins?
G proteins are enzymes that allow for an amplified response within a target cell.
In contrast to the nervous system, the endocrine system .
produces more long-lasting effects
During the cAMP second messenger system, once adenylate cyclase is activated, __________.
it uses ATP to form cAMP
The fastest-acting membrane-bound receptors are .
When calcium enters a cell through ligand-gated channels, it may .
interact with proteins, induce muscle contractions, act as an initiator of second messenger pathways within the cell
An intracellular signaling molecule produced by the binding of a ligand to a membrane-bound receptor is called a .
Put the following events of the PIP2 second messenger system in the correct order:
a. G protein activates phospholipase C.
b. Ligand-bound receptor activates a G protein.
c. PIP2 DAG + IP3.
d. IP3 triggers calcium release from endoplasmic reticulum.
b, a, c, d
Which of the organ systems below produces more focused and direct—and the fastest—responses from target cells?
The signal transuction mechanism of steroid hormones can lead to .
transcription of a particular gene
are ligands that bind to target cell receptors but do not initiate a response by the target cell.
Up regulation allows a target cell to .
increase the sensitivity of a target cell to a ligand
Which muscle fiber type experiences slow-wave potentials?
Contraction in smooth muscle is initated when ________.
calcium binds to calmodulin
Which of these statements best characterize single-unit smooth muscle?
Single-unit smooth muscle has gap junctions and light innervation by the autonomic nervous system.
Which type of muscle is subject to the several types of hormonal control?
Which of the following statements about muscles is true?
Smooth muscle thin and thick filaments are arranged obliquely.
Contraction in smooth muscle is terminated when ________.
myosin is dephosphorylated by a phosphatase
A molecule(s) common to both skeletal and smooth muscle crossbridge cycling include ________.
Smooth muscle is similar to skeletal muscle in which of the following ways?
Presence of actin and myosin
Why is there a high degree of overlap between the action potential and the contraction in cardiac fibers?
An overlap of cardiac action potential and contraction prevents summation of muscle contractions so that the heart has time to relax and fill with blood before the next contraction.
Which of these statements best characterize multi-unit smooth muscle?
Multi-unit smooth muscle lacks gap junctions but has dense innervation by the autonomic nervous system.
In what way(s) is cardiac muscle similar to smooth muscle?
It contains gap junctions, possesses pacemaker cells, and is innervated by autonomic neurons.
In which type of muscle is the function of gap junctions of the greatest importance in maintaining life?
Which of the following statements about smooth muscle is true?
Actin and myosin generate force through the crossbridge cycle.
In which types of muscle does myosin have ATPase activity?
Smooth, cardiac, and skeletal
Which of the following statements comparing smooth muscles to skeletal muscles is false?
Smooth muscles have more sarcoplasmic reticulum than skeletal muscles.
Calcium is removed from the cytosol of cardiac muscle cells by each of the following mechanisms except for ________.
Ca2+ leak channels in the plamsa membrane
Place the following structures involved in cardiac impulse conduction in the correct order:
a. bundle of His
b. AV node
c. Purkinje fibers
d. SA node
d, b, a, c
During the slow depolarization of a pacemaker potential, membrane permeability increases for which ion?
During the plateau phase of the action potential in cardiac contractile cells, ________.
sodium channels are inactivated, inward rectifier potassium channels are closed, calcium channels are open, and the membrane potential remains depolarized
Electrical signaling in the heart begins in the SA node because ________.
it depolarizes the fastest
Abnormalities within the SA node can cause which of the following symptoms?
Bradycardia or tachycardia
Which of the following statements is false?
Only the SA node can initiate an action potential.
How do pacemaker cells differ from contractile cells?
Pacemaker cells are autorhythmic and do not contract.
Which type of membrane junctions are located at intercalated disks?
Gap junctions and desmosomes
In contrast to most other types of excitable cells, cardiac contractile cells ________.
have a plateau phase in the action potential
Blood is ejected from the left ventricle once pressure within the
ventricle is greater than pressure within the aorta.
During isovolumetric relaxation, __________.
the atria are receiving blood from the vena cavae
During which phase of the cardiac cycle are all four heart valves open?
During isovolumetric relaxation,
the AV and semilunar valves are closed and ventricular pressure is decreasing.
The increase in ventricular volume early in diastole reflects the
passive movement of blood through the atrium and into the ventricle.
What phase of the cardiac cycle is the heart in when all four valves of the heart are closed and ventricular pressure is building, but is not yet great enough to open a valve?
Which of the following events occurs during systole?
maximal arterial pressure
At the beginning of systole, when ventricular pressure exceeds atrial pressure, the AV valves close. However, initially the semilunar valves also remain closed since ventricular pressure is still not sufficiently strong enough to force them open (consequently at this point in the cardiac cycle there is no blood flow into or out of the ventricles). This phase is known as ___________.
isovolumetric contraction (phase 2)
Which of the following is true of the ventricular filling phase of the cardiac cycle?
Ventricular pressure is less than aortic pressure.
What is occurring during ventricular ejection?
The AV valves are closed and the semilunar valves are open as blood is leaving the ventricles.
The end-diastolic volume minus the end-systolic volume is the
Ventricular contractility is enhanced by ________.
Parasympathetic activity decreases nodal rate of depolarization by ________.
decreasing the flow of calcium into the cytosol
Where on the heart do the sympathetic nerves terminate?
At the SA node, AV node, and myocardium
Which of the following may increase heart rate?
Regarding ventricular volumes ________.
the larger the end diastolic volume, the larger the stroke volume becomes
Which nerve provides parasympathetic supply to the heart?
The vagus nerve
Cardiac output is increased by ________.
increasing stroke volume and increasing heart rate
When someone begins to exercise, the working tissue needs an increased delivery of blood to obtain the oxygen and nutrients necessary for the maintenance of the increased metabolism. Which of the following occurs to help enhance the blood flow to the working tissue?
Increased heart rate and stroke volume
All of the following increase stroke volume except ________.
the inspiratory phase of respiration
Which of the following is (are) the same for the left and right ventricles?
Cardiac output, heart rate, and stroke volume
End diastolic volume is influenced (directly or indirectly) by ________.
heart rate, preload, afterload, and sympathetic nerve activity
During exercise, sympathetic input to the heart is increased. Stroke volume is often maintained, or even increased, even though heart rate is also increasing. How is this possible?
The sympathetic nervous system will release epinephrine and norepinephrine, which will activate the beta 1 (β1) adrenergic receptors, on the contractile and autorhythmic cells. The calcium concentrations will increase in the contractile cells, which will result in an increased force of contraction. If the force of contraction increases, then so will the stroke volume.
The actions of norepinephrine and acetylcholine on pacemaker cells is similar in that both transmitters ________.
activate G proteins and change intracellular calcium channels
Starling's law of the heart can be stated as ________.
A change in the rate of blood flow return to the heart affects the ventricular preload, which affects the stroke volume.
The driving force for bulk flow is always __________.
a pressure gradient
Which of the following accurately describes the pressure gradient used by the body for blood flow through the vasculature?
MAP - CVP
For a given pressure gradient, blood flow is greater when __________ is increased.
Total peripheral resistance __________.
increases as blood viscosity increases
Which of the following is the equation relating cardiac output, mean arterial pressure, and total peripheral resistance?
MAP = CO × TPR
The pulsatile nature of blood pressure is greatest in which blood vessels?
Where are the arterial baroreceptors located?
aortic arch and carotid sinuses (carotid arteries)
The elastic nature of the largest blood vessel's walls allows them to act as a ________, maintaining the driving force for blood flow while the heart is relaxed during diastole.
The blood vessels of largest diameter are the ________, and the blood vessels with the thickest walls are the ________.
veins : arteries
What component of artery walls allows them to store energy that is later used to maintain continuous blood flow through the circulatory system?
Arteries have ________ compliance and ________ resistance to flow.
low : low
As part of the baroreceptor reflex response to hemorrhage, which of the following increases?
Heart rate and total peripheral resistance
Reactive hyperemia is ________.
a result of changes in blood flow (rather than metabolic rate)
Calcium channel blockers bind to Ca2+ channel proteins in vascular smooth muscle and cause ________.
dilation of vessels, lowering blood pressure
In terms of maintaining blood pressure or responding to inevitable fluctuations in blood pressure, when everything is considered, the immediate danger posed by ________, is far greater than that posed by ________.
A change in vascular resistance in response to stretch of blood vessels is called ________.
Which part(s) of the heart is (are) innervated by sympathetic nerves?
Both the SA node and myocardium
In an effort to bring mean arterial pressure back to normal after a hemorrhage, total peripheral resistance ________ because the blood flow to most organs ________. However, blood flow to the ________ and ________ is maintained because these organs are not greatly influenced by the baroreceptor reflex.
increases; decreases; brain; heart
Blood flow is increased to skeletal and cardiac muscle during exercise by ________.
Arterial baroreceptors are located in the aorta and carotid arteries so that pressure (and flow) to the ________ can be closely monitored.
brain and systemic circuit
What is the effect of mean arterial pressure in the presence of norepinephrine, vasopressin, or angiotensin II?
Increased MAP by causing vasoconstriction
In active hyperemia ________.
low oxygen levels cause arteriolar smooth muscle to relax and vasodilate
The organ that plays the greatest role in regulating blood pressure by altering blood volume is the ________.
All of the following would cause an increase in blood pressure except ________.
a decrease in cardiac output
Mean arterial pressure (MAP) is based on ________.
heart rate, stroke volume, and total peripheral resistance
A decrease in which of the following would also cause mean arterial pressure (MAP) to decrease?
A decrease in either stroke volume, total peripheral resistance, or heart rate
Control of mean arterial blood pressure by the central nervous system is controlled primarily by the ________.
Hypertension can be caused by ________.
genetics, kidney disease, or hormone imbalance
The sequence of negative feedback events that use baroreceptors to keep blood pressure within set-point is referred to as ________.
the baroreceptor reflex
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