Physiology Tests Awesome

DIRECTIONS: Choose the single best answer.

PHYSIOLOGY

Module 1 General Concepts INONE

Module 2 General Concepts IIPHYSIOLOGY > Exams > 2005 Phys P4 Exam (#1-30)PHYSIOLOGY > Exams > 2004 Phys P4 Exam (#1-30)PHYSIOLOGY > Exams > 2003 Phys P1 Exam (#1-30)

Module 3 Cardiovascular/RespiratoryPHYSIOLOGY > Exams > 2005 Phys P4 Exam (#31-60 [cardio.])PHYSIOLOGY > Exams > 2004 Phys P4 Exam (#31-60 [cardio.])PHYSIOLOGY > Exams > 2003 Phys P1 Exam (#31-60 [cardio.])PHYSIOLOGY > Exams > 2005 Phys P5 Exam (#1-20, 50 [resp.])PHYSIOLOGY > Exams > 2004 Phys P2 Exam (#1-20 [resp.])PHYSIOLOGY > Exams > 2003 Phys P2 Exam (#1-20 [resp.])

Module 4 Gastrointestinal/RenalPHYSIOLOGY > Exams > 2005 Phys P5 Exam (#21-49 [renal])PHYSIOLOGY > Exams > 2004 Phys P2 Exam (#21-50 [renal])PHYSIOLOGY > Exams > 2003 Phys P2 Exam (#21-50 [renal])PHYSIOLOGY > Exams > 2005 Phys P6 Exam (#1-20 [GI])PHYSIOLOGY > Exams > 2004 Phys P3 Exam (#21-45 [GI])PHYSIOLOGY > Exams > 2003 Phys P3 Exam (#1-10 [GI])

Module 5 Endocrine/ReproductivePHYSIOLOGY > Exams > 2005 Phys P6 Exam (#21-45 [endo.])PHYSIOLOGY > Exams > 2004 Phys P3 Exam (#1-20 [endo.])PHYSIOLOGY > Exams > 2003 Phys P3 Exam (#11-45 [endo. + repro.])

Module 6 MusculoskeletalNONE

Module 7 NeuroscienceNONE

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Directions: Choose the single best answer. While alternative answers may be partially correct, only one is fully correct.

_______1. Respiratory distress syndrome (RDS) in prematurely delivered infants is characterized by progressive collapse of alveoli and respiratory failure. The primary deficiency is a lack of surfactant production. This is associated with

a. decreased work of breathing.b. increased surface tension forces at he air/liquid interface in alveoli.c. overproduction of phosphatidylglycerol (PG) by Type II epithelial

cells of the alveoli.d. increased numbers of Type I cells in alveoli.e. all of the above.

_______2. An elderly patient has emphysema and his physician decides to characterize his lung volumes and capacities. Spirometry reveals tidal volume = 0.5L; expiratory reserve volume = 1.5L; inspiratory reserve volume = 2L. The patient then quietly breathes gas from a spirometer (volume 3L) which contains helium (He) at an initial concentration of 10%. After 3 minutes of breathing, the concentration of He at the end of quiet expiration was 5%. From these measurements his vital capacity (VC) and total lung capacity (TLC) in liters are (respectively):

a. 4.0; 5.5b. 5.0; 5.5c. 3.0; 5.0d. 2.0; 4.0e. none of the above.

_______3. Compare the alveolar ventilation rate of a patient breathing quietly at 10/minute, (tidal volume 0.5L), with that of the same individual breathing rapidly at 20/minute (tidal volume 0.3L). This individual has a physiologic dead space of 0.2L and vital capacity of 3L. The respective alveolar ventilation rates are (quiet breathing; rapid breathing) in L/minute:

a. 5; 6b. 1.5; 4c. 3.5; 6d. 4; 3e. 3; 2

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_______4. Intrapleural pressure plays a central role in breathing in a healthy individual. This pressure in such an individual is

a. always less than atmospheric pressure (PB).b. equal to PB at the end of the quiet inspiration.c. less than PB at the end of quiet expiration.d. greater than (more positive value) alveolar pressure (PA) at the peak of

inspiration.e. greater than PB during all phases of quiet breathing.

_______5.

The figure shows the relation between rate of flow of air and lung volume, with positive flow = exhalation and negative flow = inhalation. Which of the following statements is correct?

a. Point “C” represents an effort-independent region of the breathing cycle.

b. EFGHA is the path of exhalation from maximum lung volume.c. “B’ represents a region in which air flow is limited by airway collapse.d. Maximum rate of flow during exhalation is attained at low lung

volumes, rather than high lung volumes.e. Point “D” represents a region in which rate of airflow is effort-

independent.

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_______6. A healthy individual quietly inhales starting at functional residual capacity (FRC). For such a breath

a. less of the inhaled gas goes to alveoli at the apex of the lung than to alveoli at the base of the lung

b. alveoli at the base of the lung are smaller than those of the apex of the lung.

c. alveoli at the base of the lung are more compliant than those at the apex of the lung.

d. alveoli having large time constants ( = RC) will fill more slowly than those having small time constants.

e. all of the above are correct.

_______7. When a healthy individual inhales 2L of air starting from the FRC, her pleural pressure decreases from –4cm H2O to –14cm H2O. If she has an FRC of 2L, the specific compliance of her lungs is (in CM H2O –1)

a. 10b. 1.0c. 0.1d. 0.2e. 0.02

_______8. A healthy individual breathes out forcefully, at the end of quiet inspiration. Which of the following statements is correct?

a. Internal intercostal muscles are activated.b. Rectus abdominus muscle is activated.c. Transverse abdominus muscle is activated.d. All of the above muscles are activated.e. No muscles are activated, since expiration is a passive process.

_______9. In advanced stages of chronic obstructive pulmonary disease such as emphysema

a. alveolar and capillary walls are progressively destroyed.b. lung compliance is increased.c. the equal pressure point moves along the airways towards the alveoli.d. total lung capacity is increased.e. all of the above occur.

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______10. The flow of air in small airways (respiratory bronchioles) during usual breathing.

a. is laminar.b. is associated with a Reynolds number less than 2000.c. will not provide any breath sounds on a stethoscope.d. provides little (less than 20%) of the total resistance to airflow due to

frictional forces.e. is accurately described by all of the above.

______11. A clinician suspects that a patient may have a diffusion problem in the lungs due to fibrosis. She measures the diffusing capacity of the patient’s lungs (DL) using inhalation of carbon monoxide (CO) gas. CO is used rather than O2 because

a. the PO2 of alveolar gas cannot be measured.b. the Pco of capillary blood remains close to zero since CO doesn’t

dissolve easily in capillary membranes.c. CO has low solubility in blood.d. the rate of CO equilibration across the alveolar /capillary boundary is

very rapid.e. the only limitation for CO diffusion is the equilibration of CO with

alveolar gas when air is inhaled.

______12. In a 100-meter race, runners frequently do not breathe for the approximately 10 second duration of the race. Given the fact that such vigorous exercise greatly increases metabolic rate, it is probable that, during such a race

a. PA02 decreases.b. PAC02 decreases.c. VA increases.d. pH increases.e. all of the above occur.

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______13. A “anatomical shunt” in the lungs

a. is an example of a “left-to-right” shuntb. can be fully corrected clinically by administering 100% oxygen o the

patient.c. results in a lowering of the AaD02 i.e. the difference in P02 between

alveoli and arterial blood is decreased.d. is accurately described by all of the above.e. occurs when some mixed venous blood by passes the alveoli and goes

directly into oxygenated arterial blood.

______14. Ventilation/Perfusion inequalities may contribute significantly to differences in alveolar/arterial oxygen (AaD02). In a healthy individual standing upright

a. The VA/Q ratio is uniformly equal to 1.0 throughout the lungs.b. The VA/Q ratio is greatest at the base of the lungs.c. The ventilation is greater at the apex than at the base of the lungs.d. Both ventilation and perfusion are greater at the base than at the apex

of the lungs.e. Exercise increases the differences in VA/Q ratio between base and apex

of lungs.

______15. Which of the following statements is incorrect?

a. Fetal hemoglobin (Hb) has a greater affinity for O2 than does adult Hb.b. The concentration of Hb in the blood greatly affects the P02 of that

blood.c. The affinity of Hb for O2 is increased by the presence of carbon

monoxide (CO).d. CO has greater affinity for Hb than does O2 .

e. Decreased temperature and increased pH result in increased affinity of Hb for O2 (i.e. a shift of the Hb – PO2 curve to the left).

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______16. CO2 is transported in the blood

a. in smaller amounts than is O2 b. at lower values of partial pressure in arterial blood than is O2.c. mainly in the form of CO2 dissolved in plasma, since CO2 is 20 times

more soluble in plasma than is O2.d. independently of the values of PC02 of arterial and venous blood.e. is accurately described by all of the above.

______17. Ventilation rate

a. increases if PaC02 decreases in the presence of constant Pa02.b. increases if Pa02 increases, in the presence of constant PaC02.

c. will change more rapidly (i.e. is more sensitive) in response to changes in PaC02, if Pa02 increases.

d. is more sensitive to change in Pa02 if Pa C02 is elevated.e. is usually more sensitive to changes in Pa02 than to changes in Pa C02.

______18. Peripheral and central chemoreceptors of the pulmonary system

a. provide direct excitatory input to centers located in the medulla.b. mainly provide direct inhibitory input to centers located in the pons.c. provide sensory input to the same group of neurons that receive

sensory input from the vagal stretch receptors and pneumotaxic center.d. are most sensitive to changes in arterial P02 in usual quiet breathing.e. are activated by stretch receptors located in large airways.

______19. Sustained exercise at an intensity beyond the anaerobic threshold results in

a. increased blood pH.b. increased arterial P C02

c. increased arterial P02.d. decreased VC02.e. all of the above.

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______20. A patient with pneumonia has a difference in alveolar/arterial oxygen (AaD02 = PA02 –Pa02) of 30 mms Hg. He is given 50% supplemental oxygen to breathe using a facemask. He is lying down quietly on a bed and has steady measured rates of oxygen consumption (V02) and carbon dioxide production (VC02) of 250 ml/min and 250 ml/min respectively. Atmospheric pressure is 747 mms Hg. Use the alveolar air equation (given below) to calculate what his new AaD02 is following the supplemental O2 therapy, given that arterial blood sampling reveals a Pa02 = 80 mms Hg.

Alveolar air equation: PA02 = F I02 (PB-PH20) – PAC02/ R,

Where FI02 = fraction of O2 in inspired gas (0.5).PH20 = partial pressure of saturated water vapor at body temperature. 7 mms Hg)PAC02 = partial pressure of C02 in alveolar air (40 mms Hg).R = Respiratory Exchange Ratio (VC02/V02)

On the basis of these measurements, his AaD02 is

a. 30 mms Hgb. 230 mms Hgc. 350 mms Hgd. 100 mms Hge. 10 mms Hg

______21. X is freely filtered and secreted. If 50% of X binds to plasma protein during circulation. Which of the following is true?

a. Cx = Cin b. Cx = CPAH

c. Cx < CPAH

d. Cx = 0e. Cx < Cin

______22. The filtered load of X is 120 mg/min. If urine volume is 2 ml/min. and the concentration of X in the urine is 100 mg/ml. and GFR is 120 ml/min. What is clearance of X?

a. 20 ml/minb. 100 ml/minc. 120 ml/mind. 200 ml/mine. 220 ml/min

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______23. Contraction of the afferent arteriole will do all of the following except __________.

a. decrease RPFb. increase oncotic pressure in the peritubular capillaryc. decrease GFRd. increase mean arterial pressure

______24. Pete has polydipsia: a psychosis associated with uncontrolled intake of pure water. He is constantly drinking water. After drinking lots of water, his plasma osmolarity will initially be ___________ resulting in _____________ ADH release followed by __________ in urine osmolarity and ___________ urine flow rate (urine volume per time).

a. decreased, more, decreases, decreasedb. decreased, less, decreases, no changec. increased, no change in, increases, increasedd. increased, more, no change, decreasede. decreased, less, decreased, increased

______25. Which of the following is critical to creation of the hyperosmotic medulla?

a. Active NaCl reabsorption at the TALb. ADHc. passive urea reabsorption at the collecting ductd. counter current flow in the vasa rectae. all of the above are necessary

______26. Congential diseases resulting in formation of glomerular basal lamina that have few negatively charged proteoglycans forming this meshwork results in all of the following except ______________.

a. proteinuriab. a relative increase in medium sized (6-8 nm) neutral proteins in the urinec. a decrease in peritubular oncotic pressured. increase in the oncotic pressure of urinee. increase in urinary flow rate

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______27. Sally has chronic renal failure with progressive loss of functional renal capacity. Her doctors have been following plasma creatinine levels as an indication of her decreasing GFR. What would happen to Pcr (compared to Pcr in the disease stater) if Sally was given a drug that reversed all adverse effects of her renal failure.

a. Pcr would riseb. Pcr would decreasec. Pcr would not changed. Pcr would stop decreasing and stay stablee. Pcr would stop increasing and stay stable

______28. Glutamine metabolism in the kidney plays an essential role in __________________.

a. acid-base balanceb. secretion of organic anionsc. production of ammonium in the proximal tubuled. regeneration of bicarbonate by the proximal tubulee. all of the above

______29. Bill’s filtration fraction is 0.16. His Ccreatinine = 100 ml/min. His urine volume and urinary PAH concentration are 2 ml/min and 625 mg/ml, respectively. What is Bill’s PAH secretion rate?

a. 10 mg/minb. 600 mg/minc. 805 mg/mind. 1050 mg/mine. cannot determine

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For questions 30-35 use the following answer choices (where V = urine volume/time, COsm = osmolar clearance, and CH2O = free water clearance):

A. V = COsm B. V > COsm

C. COsm = 0D. CH2O < 0E. COsm = CH2O

______30. Which answer choice best describes a person taking a loop diuretic?

______31. Which answer best describes a person that has diabetes mellitus (saturation of glucose reabsorption in the PT)?

______32. Which answer best describes a person that has central diabetes insipudus (not making ADH)?

______33. Which person is responding to dehydration?

______34. Which of the above relationships A-E can never happen?

______35. If V is equal under all conditions, which scenario would decrease plasma volume the greatest?

______36. If Jake’s plasma pH is 7.4 and he has a pCO2 < 40 mmHg, Jake must have?

a. acidosisb. alkalosisc. bothd. neithere. cannot determine

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______37. Substance X is freely filtered and not bound to plasma protein and completely reabsorbed. Betty is given an experimental drug that decreases Cx but has no affect on Cin. What does this experimental drug do?

a. decreases GFRb. increases GFRc. block reabsorption of Xd. increase reabsorption of Xe. decrease RPF

______38. Which patient has respiratory alkalosis?patient [HCO3

-] PCO2 PHA. 15 40 7.26B. 14 20 7.47C. 24 40 7.4D. 26 60 7.26E. 30 40 7.5

______39. Paul’s pCO2 is 16.7 mmHg and his [HCO3-] is 10 mM. What is his pH?

a. 6.2b. 7.2c. 7.4d. 8.2e. cannot determine

______40. Which of the following is secreted in to the proximal tubule:

a. Na+

b. organic anionsc. glucosed. inuline. bicarbonate

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______41. Jake’s osmolar and free water clearances are 4 and –2 L/min, respectively. After setting his plasma inulin levels to 1.0 mg/ml, his inulin clearance was 120 ml/min. Calculate his inulin excretion rate.

a. 1 mg/minb. 6 mg/minc. 10 mg/mind. 60 mg/mine. 120 mg/min

______42. An increase in filtration fraction will _____________ Na+ reabsorption at the proximal tubule.

a. decreaseb. increasec. not changed. all of the above

______43. Ms. Dubya has congestive heart failure. She has pulmonary edema and has been treated with a loop diruetic that blocks the tri-transporter and a K supplement. Dr. Bob comes along and decides to give Ms. Dubya another diuretic in addition to her other medications. Shortly after administering this second diuretic in addition to the first diuretic and K supplement, Ms. Dubya has a heart attack and dies. What type of diuretic did Dr. Bob most likely and inappropriately add to Ms. Dubya’ therapy?

a. a carbonic anhydrase inhibitorb. mannitolc. a Na/Cl cotransporter inhibitord. an inhibitor of the Na channel in the collecting ducte. cannot say

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______44. Which of the following anatomical arrangements of the renal vasculature make the kidney unique?

a. the kidney vasculature includes two capillary beds in seriesb. the vasa recta system runs in counter-currentc. the glomerular capillary is surrounded by two contractile arteriolesd. the glomerular capillary is made by fenestrated endothelial cellse. all of the above

______45. Which vascular element in the kidney presents the majority of resistance to blood flow?

a. vasa rectab. afferent arteriolec. efferent arterioled. glomerular capillarye. b and c

For questions 46 – 49 use the following data set:patient Urine flow

(ml/min)UOsm

(mOsm/kg)POsm

(mOsm/kg)A 6 100 300B 6 200 300C 6 300 300D 0.5 600 300E 2 1200 300

______46. Which patient is excreting the most free water?

______47. Which patient is most likely taking a diuretic that blocks the ADH receptor?

______48. Which patient has the highest osmolar clearance?

______49. Which patient might have a liver disease that washes out the medullary hyperosmotic gradient due to aberrant protein metabolism?

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______50. Glomerulotubular balance happens because?

a. RPF sets oncotic pressureb. plasma protein levels set oncotic pressurec. filtration at the glomerulus concentrates plasma proteinsd. filtration is isoosmotice. all of the above

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MEDICAL PHYSIOLOGY PHASE 2 EXAMINATION KEY

APRIL 12, 2004

1. B

2. A

3. E

4. C

5. E

6. E

7. C

8. D

9. E

10. E

11. B

12. A

13. E

14. D

15. B

16. B

17. D

18. A

19. C

20. B

21. C

22. D

23. B

24. E

25. E

26. B

27. B

28. E

29. D

30. A

31. A

32. B

33. D

34. C

35. D

36. C

37. C

38. B

39. C

40. B

41. E

42. B

43. D

44. E

45. E

46. A

47. A

48. E

49. C

50. C

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_______1. An individual drinks 500ml of hypertonic saline. Within a short time (say 20 minutes), assuming all of this fluid is still in his body:

f. there will be increased volume of the extracellular fluid compartment.g. there will be an increase in volume of the intracellular compartment h. there will be a decrease in volume of the vascular compartment.i. the volume of the interstitial fluid compartment will be unchanged.j. the volume of the vascular compartment will be unchanged.

_______2. Intrinsic membrane proteins

f. are usually held in place in the membrane by means of charge interactions with lipid molecules.

g. may be removed from membranes by solubilizing them using detergents.

h. are always distributed symmetrically across the bi-lipid layer.i. are usually linked to carbohydrate molecules as glycoproteins on the

inner face (intracellular side) of the membrane.j. are accurately described by all of the above.

_______3. In comparison with skeletal muscle fibers, smooth muscle cells have

f. more troponin molecules.g. higher myosin concentration.h. less concentration of actin moleculesi. all of the above.j. no sarcomeres.

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_______4.

Sarcomere Length

The diagram above was obtained from a single muscle fiber and represents the passive

and active tensions the fiber is capable of generating at particular sarcomere lengths.

Which of the following statements is correct for a muscle which is stimulated to contract

starting at the sarcomere length given by point D?

f. Under isometric conditions, the path of the contraction is given by XY1 B A.

g. Under afterloaded isotonic conditions (load given by: A) the path is XY1 Z C.

h. Under eccentric conditions of contraction the path would be XY2Z.i. Shortening of the active muscle under load A will be greater than that

under load E.j. Under after-loaded isotonic conditions (load: E) the path of the

contraction would be XF.

_______5. Diffusion is an effective process for the movement of nutrients and other molecules only over small distances because

f. the rate of diffusion is directly proportional to the distance traveled.g. the diffusion coefficient is directly proportional to the square of the

molecular weight of the molecule.h. the time of diffusion increases as the square of the distance over which

the diffusion takes place.

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i. large molecules only move small distances by diffusion.j. the diffusion coefficient is proportional to distance.


_______6. The osmolarity of a solution, as defined by the Van’t Hoff equation,

f. is independent of temperature.g. depends upon the degree of dissociation of the solute.h. is proportional to the osmotic coefficient ().i. is proportional to the molar concentration of the solute.j. is accurately described by all of the above.

_______7. Red blood cells (having an osmolarity of 0.290 osmoles/liter) are placed in a solution of particles X, having an osmotic pressure of 0.4 osmoles/liter. Which of the following statements is true?

f. The cells will increase in volume if molecules X cannot penetrate cell membranes.

g. The cells will not change in volume if the molecules X are able to freely penetrate the cell membranes.

h. The solution of molecules X is hypo-osmotic in comparison with the intracellular contents of the cells

i. The cells will increase in volume in the steady state, if molecules X can freely penetrate the cell membranes.

j. The cells will shrink in volume in the steady state if X easily penetrates cell membranes.

_______8. L-glucose exhibits movement characteristics across muscle cell membranes which are very different from those of D–glucose. For example, the rate of transport of L-glucose into muscle cells is not affected by the presence of metabolic inhibitors, is not affected by competitive inhibition from other molecules of similar structure and does not exhibit saturation kinetics. It is known that D–glucose is transported into muscle cells by facilitated diffusion. From these facts, we may conclude that L–glucose movement across muscle cell membranes is

f. by secondary active transport.g. by primary active transport.h. probably much faster than that of D-glucose.i. probably by simple diffusion.

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j. occurring by facilitated diffusion.

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_______9. Many cells import neutral, hydrophilic amino acids against their own concentration gradient. This transport mechanism:

f. utilizes the energy of the Na+ concentration gradient.g. is an example of secondary active transport.h. would be enhanced by increasing extracellular Na+ concentration.i. would be inhibited by agents which decrease cellular metabolism.j. is accurately described by all of the above.

______10. The Na+ - H+ exchange transport protein protects cells from acidification because affinity of the protein for H+ increases, and extracellular Na+ is exchanged for intracellular H+, when the pH decreases. A similar increased affinity of the protein for H+ is induced by tumor promoters, growth factors and mitogens. When these agents are present:

f. there will be increased outflux of Na+ from cells.g. the intracellular H+ concentration will increase.h. intracellular pH will decreasei. the Na+/ K+ - ATP-ase pump system will be inhibited.j. there will be a net outflux of H+ ions from the cells.

______11. The tight junctions joining the epithelial cells of the small intestine and proximal tubule of the kidney

f. are leaky to water, small water-soluble molecules and ions.g. are leaky to glucose and neutral amino acids.h. permit the movement of Na+ / K+ -ATP-ase molecules from the

basolateral to the brush border membranes of the cells.i. contain the transport proteins responsible for facilitated diffusion of

glucose across the epithelial cells.j. are impermeable to water and water-soluble molecules.

______12. The electrochemical potential energy (x) of a charged molecule X+ in solution

f. is independent of the concentration of X+.g. is directly proportional to the concentration of X+.h. will decrease if the electrical charge, or valence, of X+ increases.i. determines if X+ will move to a region where the potential energy is

different.j. is correctly described by all of the above.

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______13. The equilibrium potential of X- is

f. the transmembrane voltage difference required to produce an electrical force equal and opposite to the chemical concentration force for X-

across the cell membrane.g. the potential at which there is no movement of X- across the membrane

in either direction.h. the chemical concentration of X- which balances osmotic forces across

the membrane.i. equal to the cellular membrane potential.j. equal to the balance of cell-ions across the membrane.

______14. The two compartments A and B are separated by a membrane permeable only to X- ions. A voltage of –60mV is maintained across the membrane. Use the Nernst equation to select the correct answer, assuming the temperature is held at 29.2 C:

f. X- is in equilibrium across the membrane.g. There will be a net movement of X- from B to A.h. The electrical energy gradient is less than the chemical energy

gradient.i. There will be a net movement of X- from A to B.j. The equilibrium potential for X- in this situation is –100mV.

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______15. The drug digitalis inhibits the cell membrane Na +/ K+ - ATP-ase. If this drug is added to muscle cells in vivo:

f. There will be increased intracellular concentration of Na+ ions.g. There will be a depolarization of the resting membrane potential.h. There will be decreased intracellular concentration of K+ ions.i. The muscle membranes will exhibit increased excitability.j. All of the above will occur.

______16. If extracellular K+ concentration is increased in the fluid surrounding nerve and muscle fibers

f. the magnitude (size) of subsequent action potentials will be decreased.g. the resting membrane potential will be depolarized.h. the nerve and muscle fibers will be more easily excitable.i. all of the above will occur.j. the membrane potential will be hyperpolarized.

______17. The drug TTX (tetrodotoxin) specifically blocks Na+ channels. Adding this drug to the fluid surrounding nerve fibers will, according to the Chord Conductance equation, cause:

f. decreased K+ conductance.g. depolarization of the membrane potential.h. no change in membrane potential.i. increased Na+ conductance.j. hyperpolarization of the membrane potential.

______18. The process of accommodation in nerve and muscle fibers:

f. affects both Na+ and K+ channels.g. decreases K+ conductance (gK). h. increases the number of Na+ channels open at a given time.i. occurs in response to a rapid depolarization.j. renders the cell membranes hyper excitable.

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______19. The relative refactory period of the action potential is associated with

f. depolarization of the cell membrane.g. mainly inactivation of Na+ channels.h. mainly hyperpolarization of the cell membrane.i. decreased K+ membrane conductance.j. increased Na+ membrane conductance.

______20. The increased speed of conduction of action potentials along myelinated nerve fibers occurs in part because myelin:

b. decreases the length constant () of the axon.c. decreases the capacitance of the axon.d. enables generation of the action potential to occur at any point along

the axon.e. increases the diameter of the axon.f. increases the intracellular electrical resistance along the axon.

______21. The end plate potential (EPP) of the nerve-muscle junction

f. results in the generation of muscle fiber action potentials within the synaptic cleft.

g. occurs because the action of acetyl choline is to open K+ channels only in the synaptic cleft of the post synaptic membrane.

h. is the consequence of the opening of voltage-gated channels present in the muscle membrane of the synaptic cleft.

i. is accurately described by all of the above.j. occurs because of the opening of ligand-gated channels in the muscle

membrane of the synaptic cleft.

______22. In the Lambert-Eaton syndrome, patients exhibit muscle weakness because they produce anti-bodies against membrane Ca++ channels. These channels

f. are present in the motor nerve terminals of the nerve-muscle junction.g. are located in the post-synaptic muscle membrane.h. are necessary for the outflow of Ca++ from nerve terminals which

causes the release of vesicles of acetyl choline from the terminals.i. are also the channels through which the movement of Na+ and K+

occurs across the post-synaptic muscle membrane.j. are directly responsible for the effects of anti-cholinesterase drugs.

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______23. A motor unit of a skeletal muscle

a. consists of a motor nerve and all of the muscle fibers it innervates.b. would be expected to contain many muscle fibers (say, 2000 fibers) if

the unit is necessary for fine (or precise) control of movement, as in the case of muscles of the eye.

c. can contain fibers of several different types, such as fast (type 2) and slow (Type 1) fibers.

d. would be recruited first, if the unit contains fast, fatigable (type 2B) fibers.

e. is accurately described by all of the above.

______24. Increased skeletal muscle performance can be obtained in vivo by the process of summation. In this process

a. intracellular Ca++ levels are rapidly decreased by increasing the speed of the sarcoplasmic reticulum Ca++/ATP-ase pumps.

b. intracellular Ca++ levels are sustained at a high level as a consequence of repetitive stimulation.

c. maximum tetanic contraction is obtained via low frequency stimulation when the muscle is routinely activated under usual daily conditions.

d. there is increased binding of Ca++ ions to thick filaments.e. activity of the DHPR receptors (of the transverse tubules) and RYR

receptors (of the sarcoplasmic reticulum) is decreased below resting values.

______25. A skeletal muscle fiber which is required to shorten rapidly over large distances but not required to develop large active tensions, would be expected to

a. contain many myofibrils in parallel.b. contain many sarcomeres in parallel.c. contain many sarcomeres in series d. be classified as a Type I fiber.e. have a very large (> 100m) fiber diameter.

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______26. The speed of contraction of a skeletal muscle fiber is

a. determined mainly by the speed of the myosin ATP-ase of that fiber.b. independent of the load on that fiber.c. greater if the fiber is undergoing an eccentric contraction than when

undergoing a lightly-loaded after loaded isotonic contraction.d. determined mainly by the number of myofibrils in parallel rather than

in series in that fiber.e. not accurately described by any of the above.

______27. In malignant hyperthermia (MH), patients exhibit severe muscle contractions and rigidity in response to administration of anesthetics such as halothane and ether. This situation may be caused by

a. uncontrolled release of Ca++ ions from the sarcoplasmic reticulum (SR) into the sarcoplasm.

b. sustained activation of the RYR channel of the SR.c. sustained activation of the DHPR receptor of the transverse tubule.d. inability of the SR Ca++ ATP-ase pumps to remove elevated levels of

Ca++ from the sarcoplasm.e. all of the above.

______28. Fatigue of skeletal muscle fibers is

f. associated with greatly reduced levels of intracellular ATP.g. associated with greatly reduced pH (about 6.0) during repetitive

exercise of low intensity.h. often associated with increased inorganic phosphate ions in the

sarcoplasm (to almost 20 times the resting level in working muscles).i. most often associated with failure of the Type I muscle fibers to

continue contracting.j. accurately described by all of the above.

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______29. The energy cost of contraction is much less in smooth muscles than in skeletal muscles. This is because

f. ATP- hydrolysis occurs in order for Ca++ bind to troponin, but not for Ca++ binding to calmodulin.

g. phosphorylation of myosin light chains is necessary to activate the sliding filament mechanism in smooth muscles but not in skeletal muscles.

h. crossbridge cycling is much slower in active smooth muscles than in active skeletal muscles.

i. Ca++ ions are not removed from the sarcoplasm in smooth muscle cells by the action of Ca++/ATP-ase pumps.

j. all of the above are correct.

______30. Crossbridge cycling in smooth muscle cells decreases when the crossbridges are dephosphorylated. This occurs when

a. Ca++ concentration increases.b. myosin light chain kinase (MLCK) becomes active.c. myosin phosphatase dephosphorylates the myosin light chain.d. all of the above occur.e. the Na+/K+- ATP-ase pump restores the balance of Na+ and K+ across

the cell membrane.

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In the following cardiovascular questions

(#31-60), the common cardiovascular

variables are represented by the following

abbreviations:

Heart Rate: HR

Stroke Volume: SV

Cardiac Output: CO

Mean Arterial Pressure: MAP

Total Peripheral Resistance: TPR

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______31. In a recumbent person with a normal cardiovascular system, which of the following about blood pressure is true?

a. Mean blood pressures in the major arteries of the systemic and pulmonary circulations are identical.

b. MAP = TPR ÷ CO.c. The blood pressure difference between the large arteries and the right

atrium is virtually the same across most organs of the systemic circulation.

d. The largest pressure drop in a systemic organ circulation is usually across the veins.

e. Both b and c.

______32. Blood flow through an organ in the systemic circulation:

a. Is caused by mean arterial pressure being greater than right atrial pressure.b. Increases when organ vascular resistance increases.c. Decreases when arteriolar smooth muscle tone increases.d. Decreases when arteriolar radii increases.e. Both a and c.

______33. Before an experimental intervention a patient’s HR = 67 bpm, SV = 75 ml and MAP = 90 mmHg. The intervention caused HR to increase to 100 bpm without a change in either SV or MAP. In response to the intervention, how did TPR change to maintain MAP at 90 mmHg?

a. TPR increased by about 3 mmHg/L/min.b. TPR decreased by about 6 mmHg/L/min.c. TPR decreased by about 20 mmHg/L/min.d. TPR did not change.e. Question cannot be answered from the given information.

______34. Using the end of ventricular diastole as the starting time, what is the correct open/close sequence of the atrioventricular (AV) and semilumar (SL) valves during a heart beat?

a. SL open, AV open, SL close, AV close.b. SL close, SL open, AV close, AV open.c. AV close, SL open, AV open, SL close.d. AV close, SL open, SL close, AV open.e. AV open, SL open, SL close, AV close.

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______35. In cardiac muscle, conduction of an action potential to an adjacent fiber:

a. Occurs in part because of pathways with low electrical resistance in the intercalated disk regions.

b. Is due primarily to stimulation of ß-adrenergic receptors in the gap junction regions of the adjacent fiber.

c. Occurs most readily when the Na+-channel inactivation mechanism is completely “turned off” in the adjacent fiber.

d. Occurs at a higher velocity in the atrioventricular node than in the Purkinje fibers.

e. Both a and c.

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Drawn below is a recording of two successive “fast response” ventricular action potentials in a normal heart. Use this drawing to answer questions 36 and 37.

______36. Identify the true statement about mechanisms underlying this membrane potential recording:

f. The resting membrane potential between E and A2 is about -90 mv because Na+-channel conductance is much higher than K+-channel conductance.

g. Inward Ca++ flux (current) is much higher between E and A2 than at C.h. The rapid depolarization at B is due primarily to a rapid increase in

“slow channel” conductance.i. K+-channel conductance at C is much higher than at A.j. The Na+-channel inactivation mechanism is “turning off” between D

and E.

______37. Which mechanisms and events are correctly associated with these membrane potential changes?

f. The P-wave of the electrocardiogram is produced by the depolarization at B.

g. Between E and A2 an action potential was generated in the sinoatrial node.

h. The sarcolemma is in its absolute refractory period between D and A2.i. Between D and E the predominant activity of the sarcoplasmic

reticulum is release of Ca++ into the cytosol.j. The maximum contractile tension generated by the first action

potential occurs around B2.

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-100

+30

0MembranePotential (mv)

Time (msec)

-50

0 300150 450 600 750

•

••

•

• •

•

A A2

B B2

C

D

E



______38. The diastolic (phase 4) depolarization between action potentials in sinoatrial node fibers:

a. Is due in part to gradual increase in K+-channel conductance.b. Is due in part to a gradual increase in Ca++ influx.c. Is caused by stimulation of ß-adrenergic receptors by norepinephrine.d. Normally occurs in atrial fibers also.e. Normally occurs at a slower rate than in atrioventricular node fibers.

______39. Action potentials in sinoatrial node fibers:

f. Normally occur before those in the right and left bundle branches during a heart beat.

g. Are not conducted to adjacent atrial fibers.h. Normally occur at a lower frequency than heart rate.i. Have a rapid depolarization phase (phase 0) that is caused primarily by

increased conductance of fast Na+-channels.j. Increase in frequency in response to increased stimulation of

muscarinic cholinergic receptors.

______40. Which statement about Ca++ during a heart beat is true?

a. The sarcolemmal Ca++ influx during an action potential is normally sufficient to fully saturate the Ca++-binding sites on troponin C.

b. Ca++ release from the sarcoplasmic reticulum is triggered by the Na+ influx during an action potential.

c. The increase in cytosolic [Ca++] produces contraction only after Ca++ binds to calmodulin.

d. The increase in cytosolic [Ca++] in response to an action potential is enhanced when sarcolemmal ß-adrenergic receptors are stimulated.

e. The recovery of cytosolic [Ca++] after its initial increase is due primarily to diffusion of Ca++ from cytosol to extracellular fluid.

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______41. Using the left ventricular pressure-volume loop for one cardiac cycle drawn below, identify the correct statement about the cardiac cycle.

f. The second heart sound begins at D.g. The mitral and aortic valves are both closed between C and D.h. The mitral and aortic valves are both open between F and A.i. By definition, ventricular end-systolic volume is the ventricular

volume at E.j. Left atrial systole accounts for the volume increase between A and B.

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D

C

E

F

AB

Left VentricularPressure (mmHg)

Left VentricularVolume (ml)

••

•••

•



Drawn below is aortic blood pressure associated with 3 successive heart beats. Use this drawing to answer questions 42 and 43.

______42. Which cardiac event is correctly associated with these aortic pressure tracings?

e. The first heart sound begins between A and B.f. The left ventricle is filling at C.g. The aortic valve opens at D.h. Left ventricular pressure reaches its highest level between E and F.i. The period of left ventricular ejection is from C to E.

______43. Which is true about aortic blood pressure as shown above and the events associated with it?

f. By definition, aortic diastolic blood pressure is the value at D.g. Aortic pulse pressure is about 120 mmHg.h. MAP is between 85-95 mmHg.i. Blood flow through the downstream arterioles is occurring between A

and D, but not between D and F.j. The rise in aortic pressure between B and C is due to smooth muscle

contraction in the aorta and its major branches.

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Arterial Pressure(mmHg)

120

0

80

40

Time (sec)0

••

•

••

•AB

C

D

E

F



______44. Which mechanism normally contributes to the increase in HR produced by increased sympathetic nerve stimulation in the sinoatrial node?

f. Increased rate of rise of the phase 4 depolarization.g. Change in the membrane potential threshold for action potentials to a

more negative value.h. Increased Na+ influx through “funny” channels during phase 4.i. Decreased Ca++-channel conductance during phase 4.j. Both a and c.

______45. The Frank-Starling mechanism that controls SV:

f. Will tend to decrease SV when venous return becomes greater than CO.g. Is due in part to a change in the extent of interfering overlap of actin

filaments in a sarcomere when ventricular end-diastolic fiber length is changed.

h. Is related to the intrinsic ventricular muscle mechanism that increases contractile fiber shortening when preload is increased.

i. Requires stimulation of cardiac ß-adrenergic receptors to increase SV.j. Both b and c.

______46. An increase in ventricular contractility in the normal heart:

a. Increases the peak pressure generated by an isvolumetrically contracting ventricle from a given end-diastolic fiber length.

b. Is the cause of a fall in SV when ventricular afterload increases.c. Is produced normally by a reduction in Ca++-binding to troponin C.d. Causes SV to fall when it occurs without a simultaneous change in

ventricular preload and afterload.e. Reduces myocardial O2 consumption.

87



______47. Drawn below is the left ventricular pressure-volume loop during a cardiac cycle with end-diastolic volume and end-systolic volume labeled by 1 and 2, respectively. Cardiac sympathetic nerve stimulation accompanies a fall in arterial blood pressure in response to a cardiovascular challenge. However, ventricular end-diastolic volume is not altered. Which point (a-e) represents the new end-systolic volume?

______48. Pulse pressure in the major arteries of the systemic circulation:

a. Declines when SV increases.b. Declines during hemorrhage.c. Decreases with age because major artery compliance increases.d. Is normally less than 10 mmHg.e. Is, by definition, equal to (systolic blood pressure + diastolic blood

pressure).

______49. The tone of arteriolar smooth muscle increases when:

a. membrane hyperpolarization reduces Ca++-channel conductance.b. the cytosolic concentration of the Ca++-calmodulin complex decreases.c. an increase in -adrenergic receptor stimulation increases the cytosolic

concentration of inositol triphosphate (IP3).d. an increase in endothelial release of nitric oxide increases cytosolic

[cGMP].e. Both b and c.

88

LV Pressure (mmHg)

LV Volume (ml)

•

•• •

• •

a

b

1

2

c

d

• e



______50. The metabolic mechanism that controls arteriolar resistance:

f. Involves a vasodilator influence of metabolites in the interstitial fluid on arteriolar smooth muscle tone.

g. Causes arteriolar vascular resistance to increase in an organ when its O2 demand increases above the initial O2 supply.

h. Causes coronary blood flow to fall when heart rate increases.i. Is one cause of reactive hyperemia following release of blood flow

occlusion.j. Both a and d.

______51. An event increased blood flow through an organ in the systemic circulation even though there were no changes in MAP and right atrial pressure. Each of the following could have been a cause of this increase in blood flow through a direct action on arterioles EXCEPT:

a. Decreased action potential frequency in sympathetic vasoconstrictor fibers.

b. Increased histamine release from mast cells.c. Increased nitric oxide release from endothelial cells.d. Increased plasma concentration of angiotensin II.e. Increased release of prostaglandins E2 and I2 from endothelial cells.

______52. The sympathetic vasoconstrictor fiber control of arteriolar resistance:

a. Is mediated primarily by release of epinephrine from postganglionic nerve terminals.

b. Primarily involves ß2-adrenergic receptor stimulation in arteriolar smooth muscle.

c. Is an important moment-to-moment controller of TPR.d. Changes organ blood flow in direct proportion to action potential

frequency.e. Is the most important controller of blood flow through the cerebral

circulation

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______53. An organ’s autoregulation of its steady state blood flow when MAP is elevated:

a. Requires stimulation of sensory receptors in that organ which, in turn, determines the activity of sympathetic vasoconstrictor fibers.

b. Is due in part to a myogenic relaxation of arteriolar smooth muscle when the arteriolar vessel wall is stretched.

c. Is accomplished through local mechanisms that increase arteriolar resistance.

d. Causes organ blood flow to increase in direct proportion to the increase in MAP.

e. Both b and c.

______54. Net capillary filtration is occurring in an organ, but lymph flow is less than the net filtration rate. The following values are measured:

Average capillary blood pressure (Pc): 28 mmHgPlasma colloid osmotic pressure (πp): 24 mmHgInterstitial fluid colloid osmotic pressure (πif): 5 mmHg

In this organ:

a. Capillary filtration coefficient = 0.b. Interstitial fluid hydrostatic pressure (Pif) is less than 9 mmHg.c. The net absorptive force due to proteins = 0.d. Interstitial fluid volume is decreasing.e. Both a and c.

______55. In a patient’s arm with surgically eliminated lymph outflow, there is initially no net fluid movement across the capillary walls. Subsequently, a perturbation increases average arm capillary blood pressure without any change in plasma protein concentration. If the capillary filtration coefficient is not 0, this perturbation will:

a. Initially change net transcapillary fluid movement to filtration.b. Reduce interstitial fluid hydrostatic pressure (Pif).c. Decrease interstitial fluid volume.d. Produce a continuous net filtration in the new steady state.e. Both c and d.

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______56. If the total blood flow entering the systemic veins of an intact circulation is equal to CO in a person that is lying down, which event in the veins will initially make venous return greater than CO?

a. An increase in sympathetic nerve activity to venous smooth muscle.b. An increase in venous blood pressure due to arteriolar vasodilation.c. An increase in leg venous blood volume caused by standing up.d. All of the above.e. Both a and b.

______57. In response to a sudden increase in MAP, the arterial baroreceptor reflex will:

a. Reflexly cause a further increase in MAP.b. Reduce cardiac vagal nerve nerve activity.c. Reduce -adrenergic stimulation of arteriolar smooth muscle.d. Increase ventricular contractility.e. Increase HR.

______58. Which is true about the atrial baroreceptors and the reflex they initiate?

a. The atrial baroreceptors are the sensors of the arterial baroreceptor reflex.

b. Atrial baroreceptor nerve activity increases when atrial blood volume decreases.

c. An atrial receptor-sensed fall in atrial volume will reflexly increase sympathetic nerve activity to cardiovascular effectors.

d. The atrial baroreceptor reflex is the most important mechanism in long-term regulation of MAP.

e. The atrial baroreceptor reflex has no cardiovascular role during hemorrhage.

______59. Relative to the pre-stimulus (control) level, a hemorrhaging individual with falling MAP has:

a. an increased SV due to the Frank-Starling mechanism.b. an elevated action potential frequency in arterial baroreceptor nerve

fibers.c. a decreased sympathetic vasoconstrictor nerve activity to skin.d. an increased kidney (renal) blood flow.e. an increased TPR.

91



______60. Relative to rest, dynamic exercise:

a. increases HR but not CO.b. increases active skeletal muscle blood flow primarily by reducing

sympathetic vasconstrictor nerve activity.c. reduces coronary blood flow by elevating sympathetic vasoconstrictor

nerve activity.d. increases ventricular contractility by elevating cardiac sympathetic

nerve activity.e. increases gastrointestinal blood flow by reducing sympathetic vasoconstrictor

nerve activity.

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1. a

2. b

3. e

4. e

5. c

6. e

7. d

8. d

9. e

10. e

11. a

12. d

13. a

14. B & C

15. e

16. d

17. e

18. a

19. c

20. b

21. e

22. a

23. a

24. b

25. c

26. a

27. e

28. c

29. c

30. c

31. c

32. e

33. b

34. d

35. e

36. e

37. b

38. b

39. a

40. d

41. b

42. a

43. c

44. e

45. e

46. a

47. c

48. b

49. c

50. e

51. d

52. c

53. c

54. b

55. a

56. a

57. c

58. c

59. e

60. d

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