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LS7C Exam 2 Review
Terms in this set (83)
Assume that blood pressure drops in a person because of an injury. Indicate which of the following occur by selecting "true" for does occur or "false" for does not occur.
1. Circulating levels of aldosterone will increase.
2. Circulating levels of renin will decrease.
3. The sympathetic nervous system stimulates the adrenal glands.
4. Water absorption by the distal convoluted tubule will decrease.
5. Circulating levels of angiotensin II will increase.
One of the roles of the kidneys is to help buffer body fluids so that they are not too acidic or too basic. The cells of the renal tubule secrete H+ into the tubule lumen, and absorb bicarbonate (HCO3-), passing it into the tissue fluid. True or false: During heavy exercise, the reaction shifts to the right in the nephron (lumen of the tubule).
You discover a new type of marine organism that has the kidneys of a fish but no gills. What effect would the absence of gills have on excretion of nitrogenous waste?
Nitrogenous excretion increases at the kidneys because it cannot be lost at the gills.
Freshwater fish are in a hypotonic environment. How do their gill chloride cells function in this environment?
Freshwater fish have chloride cells that actively move chloride ions into the gills, with sodium ions following.
Sometimes while traveling, people are infected with a protist parasite, Giardia. One of the side effects of Giardia infection is diarrhea. When someone has diarrhea, they lose excessive water and salt from the body. The result is loss of Na+, dehydration that leads to decreased extracellular volume and plasma volume, and decreased arterial blood pressure. Given this would the vasopressin secretion of a person infected with Giardia:
True or false: The loop of Henle is a countercurrent exchanger because it creates a concentration gradient rather than simply maintaining it.
FALSE. It is a countercurrent multiplier!
Which of the following statements explains why there is an elastic layer found in arteries, but not veins?
Blood pressure is higher in arteries than veins, and the elastic layer helps maintain the structure of the artery.
Bisphosphoglyceric acid (BPG) is a byproduct of glycolysis released into the bloodstream when an animal's supply of oxygen is low. Like protons, it decreases hemoglobin's affinity for O2. The effect of high BPG levels would be that:
hemoblobin releases more of its bound O2 than it would without BPG.
During certain stressful moments, some individuals will begin to hyperventilate—that is, their breathing will be very shallow and quick. A by-product of hyperventilation is much lowered levels of CO2 in the blood. Which of the following would you also expect to find?
increased blood pH, greater than 7.2
decreased stimulation of chemoreceptors in the brainstem
Chemoreceptors in the circulatory system detect changes in circulating <i>p</i>CO<sub>2</sub>. If CO<sub>2</sub> concentrations get too high, the rate of ventilation increases. Why does this make sense?
It makes sense because tissues that are more actively working produce more CO<sub>2</sub>.
Stimulation by the parasympathetic nervous system increases the permeability of the SA node to potassium ions, whereas stimulation by the sympathetic nervous system decreases the permeability of the SA node to this same ion.
What are desirable characteristics for a gas exchange surface, such as the endothelial cells lining the inside of lung?
a large surface area
a thickness under 10 micrometers
In systemic tissue fluids, the enzyme carbonic anhydrase catalyzes the reaction CO2 + H2O → H2CO3 (which then can dissociate into H+ and HCO3-). In fact, CO2 released from cells is converted to HCO3- ions and travels in that form in the bloodstream. HCO3- is reconverted to CO2 + H2O in the pulmonary capillaries by the same enzyme, and there the CO2 is exhaled. How is it possible for the same enzyme to catalyze reverse reactions?
The direction of a reversible reaction is influenced by the concentrations of reactants and products. In pulmonary circulation, the low CO2 concentration favors the formation of CO2 and H2O.
What is the relationship between light and dark with neurotransmitter activity in a photoreceptor and its postsynaptic cell?
Hyperpolarization of the rod cell in the light inhibits release of a neurotransmitter.
Which of the following would result in tetanus?
stimulating the muscle fiber so frequently that it cannot relax at all
All of the following would lead to an increase in the force generated by a muscle contraction EXCEPT:
increasing the number of muscle fibers activated.
increasing the frequency of muscle stimulation by the motor nerve.
maximizing the number of cross-bridges formed during a contraction.
increasing the rate at which calcium is pumped back into the sarcoplasmic reticulum.
increasing the number of motor units activated.
increasing the rate at which calcium is pumped back into the sarcoplasmic reticulum.
When compared to the leg muscles of an Olympic sprinter, the muscles of an Olympic marathoner would likely show a greater proportion of oxidative slow-twitch fibers.
If a skeletal muscle is no longer able to make enough ATP, then:
actin and myosin in the sarcomeres will remain bound.
Sensory cells and sensory neurons allow multicellular animals to sense physical and chemical cues from their environment. What key properties of these cells enable them to perform this function?
Sensory cells and sensory neurons have electrically excitable membranes that change in charge potential in response to binding an environmental signaling molecule.
Sensory cells and sensory neurons have protein receptors linked to intracellular or membrane-based signaling pathways that alter ion channel permeability.
The transduction of sound waves to changes in membrane potential takes place:
when stereocilia bend against the tectorial membrane, causing hair cell depolarization.
You measure levels of Ca2+ in various locations within a motor neuron and a skeletal muscle fiber when the motor neuron is NOT depolarized, and the muscle fiber is at rest. Where do you expect to find high levels of Ca2+?
within the sarcoplasmic reticulum of the muscle fiber
Sensory transduction requires:
a change in membrane potential.
reaction of a receptor protein with a stimulus.
alteration of the conformation of a channel protein.
Aging can sometimes lead to an increase in the stiffness at the base of the basilar membrane. What effect would this have on a person's hearing?
The person would lose the ability to hear high-pitched sounds.
What type of sensory receptor is a hair cell?
What senses do the three semicircular canals in the mammalian inner ear provide?
a sense of angular motion and balance
What is the primary function of a statolith?
to determine the direction of gravity
How are sound vibrations amplified in a vertebrate ear?
by movement of the bones of the middle ear and by differences in the surface area of the eardrum versus the oval window
Hair cells function by:
Predict which type of channel is associated with ion transport in stereocilia.
Which of the following is/are the light-absorbing compound used by photoreceptors?
What determines the specific wavelength of light absorbed by a cone cell?
the type of opsin present in the membrane
Which photoreceptor cell type is present at high concentration in the fovea?
Which of the following is the opening in the eye through which light passes?
Bipolar cells carry signals from rods and cones to:
Cone cells most likely evolved from:
The conformational change in opsin, triggered by the absorption of light by retinal, activates a G protein. What do G proteins do in the cell?
G proteins contribute to signal pathways.
G proteins influence the activity of other proteins and enzymes in a cell.
G proteins can trigger the synthesis of second messengers.
Recall that cats—and other nocturnal predators—have a greater number of rod cells in their eyes compared to cone cells. What would you predict about the color vision of cats?
Because of the decreased number of cone cells, cats have (relatively) poor color vision.
What is the function of horizontal cells in the eye?
They receive signals from multiple photoreceptors (rods and cones), enhancing contrast and adjusting photoreceptor sensitivity to light levels.
ATP hydrolysis allows for what component of skeletal muscle contraction?
cocking of the myosin head to its high-energy position
Calcium is necessary to initiate muscle contraction. Which of the following molecules binds calcium?
A researcher is comparing the size of sarcomeres in mice to those in elephants. What will he find?
Sarcomere size is relatively constant in vertebrates. As a result, mouse and elephant sarcomeres will likely be equal in size.
What is a muscle fiber?
a single cell of a muscle
What is the basic contracting unit of a skeletal muscle?
Why is calcium necessary for muscle contraction?
Calcium is needed to activate troponin so that tropomyosin can be moved to expose the myosin-binding sites on the actin filament.
What stimulates a skeletal muscle cell to contract?
an impulse from a motor neuron
You take a human smooth muscle cell and block the release of calcium from the sarcoplasmic reticulum. What effect does that have on contraction of that smooth muscle cell, and why?
Contraction still occurs because Ca2+ can enter the cell directly through Ca2+ channels in the plasma membrane and bind to calmodulin.
The power stroke corresponds to which event in muscle contraction?
sliding of actin relative to myosin filaments
Vertebrate smooth muscle cells are activated when Ca+ binds to:
Muscle contractions have _____ force at slower shortening contraction velocities compared to higher shortening contraction velocities.
Muscle fibers generate maximum force:
at intermediate lengths.
During _____ bone segments rotate closer, whereas during _____ bone segments move further apart.
Tetanus is a(n):
a muscle contraction of sustained force resulting from repeated action potentials
Muscles produce higher forces when lengthening than when shortening.
A single motor neuron and the population of muscle fibers that it innervates is called a(n):
When skeletal muscles contract such that bone segments move closer together, this action is known as:
If solution X has a 2% concentration of NaCl and solution Y has an 8% concentration of NaCl, which of the following statements is CORRECT?
Solution X is hypotonic relative to solution Y.
Osmoregulators have _____ internal solute concentrations compared to their external environment.
The body fluid of sharks has a much lower concentration of sodium chloride than that of the surrounding seawater, and sharks are able to remain in osmotic equilibrium with the external environment. How can this be the case?
Sharks store enough urea to match the total solute concentration of the surrounding seawater.
Fish in a marine environment must maintain a relatively constant ion concentration in their tissues and blood. How do the chloride cells in the gills aid fish in the removal of excess ions?
The chloride cells actively remove ions from the body and water follows by osmosis.
In most organisms, the excretion of wastes is closely tied to the maintenance of water and electrolyte balance.
Cells can regulate their internal osmotic pressure by controlling the solute concentration inside of the cell.
Two solutions of water and dissolved potassium and glucose are separated by a selectively permeable membrane that only permits the passage of water. If the two solutions have the same total solute concentration, but solution 1 has a higher concentration of potassium and a lower concentration of glucose than solution 2, which of the following statements is CORRECT?
There will be no net movement of water molecules between the solutions.
You discover a new type of marine organism that has the kidneys of a fish but no gills. Based on what you know about other aquatic organisms, the newly discovered organism is _____ compared to the surrounding water.
Metanephridia differ from protonephridia in all of the following ways EXCEPT that:
the urine produced in both systems is more dilute than the body fluids.
Most mammals excrete _____; most aquatic animals excrete _____; birds, insects, and many reptiles excrete _____.
urea; ammonia; uric acid
Which process is responsible for creating MOST of an animal's nitrogenous waste?
protein breakdown during metabolism
Which of the following statements about the protonephridia of freshwater flatworms is CORRECT?
Fluid from the body enters the protonephridia without first being filtered.
A person's blood pressure falls. Which of the following would you expect to occur?
circulating concentrations of renin will increase
water uptake by the distal convoluted tubule will increase
Which of the following CORRECTLY describes the path of excretory fluids through a mammalian nephron?
glomerulus, Bowman's space, proximal convoluted tubule, loop of Henle, distal convoluted tubule, collecting duct
One of the roles of the kidneys is to help buffer body fluids, to keep fluids from becoming too acidic or too basic. The cells of the renal tubule wall secrete H+ into the tubule lumen, and absorb bicarbonate, passing it into the tissue fluid. True or false: During heavy exercise, the reaction shifts to the right in the interstitial fluid around the nephron.
What is the function of the vasa recta?
It maintains the concentration gradient established by the loop of Henle.
An increase of _____ increases the permeability of the collecting duct to water.
ADH (antidiuretic hormone)
Which of the following processes occur within Bowman's capsule?
Which of the following statements about the control of blood volume and blood pressure is NOT true?
Angiotensin II stimulates the release of antidiuretic hormone, which increases salt and water uptake by the distal convoluted tubule.
Water levels are adjusted to meet the osmoregulatory needs of the organism in the _____ of the nephron under the control of _____, also called vasopressin.
collecting ducts; antidiuretic hormone
An individual with vitamin D deficiency will experience which of the following problems?
difficulty absorbing sufficient amounts of calcium from the diet
During starvation, humans and other animals deplete glycogen and fat reserves first, followed by protein.
When an individual has an energy surplus, he or she stores the extra energy as:
Essential amino acids are those that:
cannot be synthesized biochemically and must be taken in through the diet.
The pancreas produces a variety of secretions, including:
lipase for fat digestion.
bicarbonate ions to neutralize stomach acid.
trypsin for further protein digestion.
The _____ is the first section of the small intestine, where food enters from the stomach.
The digestive tract is well adapted for digestion and absorption. For most nutrients, once material is in the digestive tract, the digestive system does not vary its rate of absorption according to body needs.
This response is not homeostatic.
Which part of the digestive tract is the predominant location for water and mineral absorption?
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