HBY 531 Organ Systems
Mid-Term Examination
1997
Section 1: Answer the following using:
A = increases
B = no change, or remains unchanged
C = decreases
1. The duration of the sinoatrial node action potential __________ during vagal stimulation.
2. The slope of phase 4 of the sinoatrial node action potential __________ upon application of a b agonist.
3. The duration of the QRS complex __________ if the heart rate increases from 60 to 90 beats per minute.
4. The duration of the QRS complex __________ when plasma [K+] increases from 4 to 8 mM.
5. The duration of the absolute refractory period in a Purkinje fiber __________ if the plateau duration increases by 50 msec.
6. The intracellular [cAMP] in the SA node __________ during vagal stimulation.
7. The magnitude of the calcium conductance in the SA node __________ during vagal stimulation.
8. The strength of cardiac contraction __________ upon application of a b agonist.
9. Premature ventricular excitation results in _________ in ventricular filling time for the next contraction.
10. According to LaPlace’s Law, as pressure decreases, tension __________.
11. Venous constriction results in __________ in cardiac output.
12. After intravenous infusion of blood, heart rate __________ due to the Bainbridge reflex.
13. Vasodilation results in __________ in blood flow.
14. In patients with obstructive pulmonary disorders (i.e., emphysema), the FEV1/FVC ratio __________.
15. A 150 lb. patient is breathing at a rate of 14 breaths per minute and has a tidal volume of 500 ml, so that his total minute ventilation is 7 L/min. He then changes his breathing pattern to a frequency of 10 breaths per minute and a tidal volume of 700 ml. Assuming no change in dead space, his alveolar ventilation __________.
16. In patients with ventilation-perfusion mismatching, alveolar ventilation increases, arterial PO2 decreases, and arterial PCO2 __________.
17. Blood flow in Zone 2 of the lung __________ by lowering venous pressure.
18. A lightly anesthetized patient (still capable of spontaneous breathing) is artificially ventilated at his/her normal tidal volume and twice his/her normal breathing frequency with a gas mixture of 50% O2 and 50% N2 for 10 minutes. On cessation of this artificial ventilation, the patient fails to breathe for 1 minute. The most likely cause of this temporary apnea involves __________ in the activity of medullary chemoreceptors in response to changes in PCO2.
19. Stimulation of rapidly adapting receptors (i.e., pulmonary irritant receptors) constricts the airways and __________ in breathing.
20. Activation of b 2 receptors on airway smooth muscle cells results in __________ in the intracellular [cAMP].
21. Increased renal sympathetic nerve activity results in __________ in the filtration fraction.
22. Constriction of the efferent arteriole results in __________ in the glomerular capillary hydrostatic pressure.
23. An increase in flow in Henle’s loop results in __________ in afferent arteriolar resistance.
24. A rise in the filtration fraction results in __________ in the back leak of fluid through proximal tubule cell tight junctions.
25. Increased atrial stretch results in __________ in afferent arteriolar resistance.
26. A rise in plasma ANP levels results in __________ in ADH secretion.
27. A 5% increase in blood volume results in __________ in ADH secretion.
28. Increased plasma osmolarity results in __________ in the apical membrane water permeability in collecting duct cells.
29. Increased plasma angiotensin II levels results in __________ in renin secretion.
30. With the administration of furosemide, the activity of the Na,K,2Cl-cotransporter in thick ascending limb cells __________.
31. A rise in plasma angiotensin II levels results in __________ in the apical membrane K+ permeability in collecting duct cells.
32. Low plasma ADH levels result in __________ in the driving force for K+ secretion in the distal tubule.
33. The plasma bicarbonate concentration __________ with the onset of metabolic acidosis.
34. The renal bicarbonate excretion __________ following an infusion of NaOH.
35. Alveolar ventilation __________ with the onset of metabolic alkalosis.
36. Infusion of nicotine into the adrenal medulla will result in __________ in the amount of epinephrine released into the vasculature.
Section 2: For each of the following, choose the single best response.
37. In a subject exercising on a treadmill the arterial blood contains 0.20 ml O2/ml blood; a blood sample from the pulmonary artery contains 0.14 ml O2/ml blood. The subject’s O2 consumption is 400 ml/min. The subject’s cardiac output is about:
a. 7.5 L/min.
b. 6.7 L/min.
c. 5.0 L/min.
d. 4.7 L/min.
e. 3.7 L/min.
38. Which of the following statements about the behavior of isolated papillary muscles in a device for measuring isotonic contractions is FALSE?
a. Increasing the preload will increase the maximum afterload that can be lifted.
b. Increasing the preload will increase the maximum power that the muscle can generate.
c. Increasing the preload will decrease the interval between stimulation and the onset of shortening.
d. Applying norepinephrine will increase the maximum velocity of shortening (shortening with no afterload).
e. While keeping the preload constant, increasing the afterload will increase the initial velocity of shortening.
39. With regard to arterial baroreceptors,
a. afferent signals are carried via sympathetic nerves.
b. firing results in decreased heart rate.
c. firing results in increased sympathetic stimulation of the heart.
d. they are located at the junction of the right atrium and the superior vena cava.
e. both a and c are true.
40. With regard to the cardiac work loop shown above, which of the following statements is FALSE?
a. The aortic valve closes at point L.
b. The mitral valve opens at point M.
c. The mean aortic pressure is close to 115 mm Hg.
d. The stroke volume is about 80 ml.
e. The reduced ejection phase is between points O and L.
Answer questions 41-44 using the figure shown below. For each question, match the cardiovascular event with it’s correct place in the cardiac cycle.
41. The aortic valve opens at:
a. A.
b. C.
c. D.
d. F.
42. Left ventricular filling occurs at:
a. A.
b. B.
c. E.
d. G.
43. Isovolumic contraction of the left ventricle occurs at:
a. A.
b. B.
c. E.
d. F.
44. Atrial systole occurs at:
a. A.
b. B.
c. E.
d. F.
45. Binding of norepinephrine to b 1 receptors on cardiac muscle will:
a. activate adenylyl cyclase.
b. decrease intracellular [cAMP].
c. activate protein kinase A.
d. both a & c
e. a, b, & c
During a Valsalva maneuver the mean arterial blood pressure undergoes a series of changes indicated by the drawing below. For each phase indicated in questions 46-49, identify THE BEST cause-response relationship.
46. During Phase I, increased blood pressure is due to:
a. increased cardiac output caused by increased venous return.
b. increased vasoconstriction.
c. decreased vagal stimulation of the heart and increased cardiac output.
d. increased peripheral resistance.
47. During Phase II, decreased blood pressure is due to:
a. decreased cardiac output caused by decreased sympathetic stimulation of the heart and decreased venous return.
b. decreased cardiac output due to decreased heart rate.
c. increased vagal stimulation of the heart.
d. increased cardiac output.
48. During Phase III, increased blood pressure is due:
a. to increased cardiac output caused by increased venous return.
b. to increased vasoconstriction caused by decreased atriopeptin release.
c. to decreased vagal stimulation of the heart, increased cardiac output, and increased peripheral resistance.
d. solely to increased peripheral resistance.
49. During Phase IV, increased blood pressure is due to:
a. increased cardiac output, caused by increased venous return into a constricted vasculature.
b. increased vasoconstriction.
c. decreased vagal and increased sympathetic stimulation of the heart giving increased cardiac output.
d. decreased peripheral resistance.
50. As blood flows through the peripheral circulation down to the capillaries, some general hemodynamic features change. Which of the following best describes these changes?
a. Pressue and velocity decrease, while cross-sectional area and blood volume increase.
b. Pressure and blood volume increase, while cross-sectional area and velocity decrease.
c. Blood volume, cross-sectional area, and velocity increase, while blood pressure decreases.
d. Blood flow, velocity, and cross-sectional area increase, while blood pressure decreases.
e. none of the above
51. The properties of blood significantly contribute to the flow of blood through the vasculature. Which of the following statements concerning these properties is FALSE?
a. The viscosity of blood decreases as the tube diameter decreases.
b. As the shear rate increases, shear thinning decreases the apparent viscosity.
c. As the flow rate increases, leukocytes marginate at the vessel wall and increase apparent viscosity.
d. none of the above
52. Storage and release of energy in the arterial vasculature are attributable to:
a. compliance of the arterial vasculature.
b. stroke volume.
c. venous storage of blood volume.
d. both compliance of the arterial vasculature and venous storage of blood volume.
53. Which of the following factors increase the turbulence of blood flow?
a. low velocity
b. high viscosity
c. small diameter
d. all of the above
e. none of the above.
54. With moderate heart failure,
a. the cardiac function curve shifts to the right and the vascular function curve is unchanged.
b. both the cardiac and vascular function curves shift to the right.
c. both the cardiac and the vascular function curves shift to the left.
d. the cardiac function curve shifts left and the vascular function curve shifts right.
55. Which of the following does not result from decreased blood volume?
a. increased aldosterone
b. increased Na+ retention
c. decreased heart rate
d. decreased atrial natriuretic factor
e. none of the above
56. In a normal individual blood flow through the cerebral vasculature is:
a. directly proportional to mean arterial pressure.
b. constant at all physiologically relevant mean arterial pressures.
c. regulated in part by catecholamines released from sympathetic nerves.
d. unaffected by vasodilatory effects of adenosine.
57. Which of the following statements regarding the development of progressive
hemorrhagic shock is FALSE?
a. Blood loss leads to loss of hemoglobin and oxygen carrying capacity of blood and hence oxygenation of tissues.
b. Decreased blood volume leads to a decrease in lymph formation.
c. Irreversible shock will not develop if blood volume and its oxygen carrying capacity are restored before the end of the period of progressive shock.
d. Decreased arterial pressure leads to decreased tissue nutrition and cardiac nutrition.
58. In capillary fluid exchange excessive filtration over reabsorption would NOT
OCCUR in which condition?
a. severe right heart failure exhibiting high venous pressures
b. hypertension
c. immediately following severe hemorrhage
d. cirrhosis of the liver accompanied with markedly reduced ability to synthesize albumin
59. In capillary fluid exchange excessive reabsorption over filtration would NOT
OCCUR in which condition?
a. immediately following severe hemorrhage
b. severe hypovolemia resulting from sweating, diarrhea, or vomiting
c. cirrhosis of the liver accompanied with markedly reduced ability to synthesize albumin
d. normal functioning of the intestinal mucosal vasculature
60. During inspiration:
a. the volume inside of the thorax increases.
b. pressures of gas are greater in the pleural cavity than in the alveoli.
c. the alveolar transmural pressure gradient falls.
d. no air flows into the alveoli until alveolar pressure equals atmospheric pressure.
e. both a and c are true.
61. Which of the following statements is correct in describing FRC?
a. The inward directed elastic recoil of the lung is greater than that of the outward directed elastic recoil of the chest wall.
b. The inward directed elastic recoil of the lung balances the outward directed elastic recoil of the chest wall.
c. Regardless of the magnitude of the residual volume, the elastic recoil of the lung balances the elastic recoil of the chest wall.
d. Both b and c are true.
62. Lung compliance:
a. increases in restrictive pulmonary disease (i.e., pulmonary fibrosis).
b. is greater at high lung volumes.
c. represents the relationship between changes in the pressure distending the alveoli and the corresponding changes in lung volume.
d. can only be measured when air is flowing into or out of the lungs.
e. depends upon the elastic properties of the lungs and chest wall as well as surface tension forces.
63. Surfactant:
a. decreases surface tension independent of lung volume (surface area).
b. has a greater ability to reduce surface tension at smaller lung volumes (smaller alveolar surface area) than at larger lung volumes (larger alveolar surface area).
c. has no effect on maintaining stability of alveolar volumes of different sizes.
d. ensures relatively even distribution of the ventilation throughout the lung.
64. Which of the following increase airway resistance?
a. forced expirations
b. low lung volumes
c. stimulation of the parasympathetic postganglionic fibers innervating the bronchial smooth muscle
d. high ventilation-perfusion ratio
e. all of the above
65. Which of the following lung volumes cannot be measured with a simple
spirometer?
a. tidal volume
b. residual volume
c. inspiratory reserve volume
d. expiratory reserve volume
66. At an altitude of 10,000 feet, the barometric pressure is approximately 530
mm Hg. The partial pressure of O2 is about:
a. 0.5 mm Hg.
b. 10 mm Hg.
c. 50 mm Hg.
d. 110 mm Hg.
e. 160 mm Hg.
67. Which of the following is NOT TRUE of the normal upright lung?
a. Uneven pulmonary ventilation is caused, at least in part, by the effect of gravity.
b. Apical (upper) regions of the lung are more compliant than basilar (lower) regions of the lung.
c. Ventilation per unit volume is higher at the base of the lung than near the apex of the lung.
d. Alveoli at the base of the lung have a smaller initial volume than those at the apex of the lung.
e. Intrapleural pressure is less negative at the base of the lung than at the apex of the lung.
68. The pulmonary and systemic circulations have the same:
a. mean arterial pressure.
b. vascular resistance.
c. compliance.
d. blood flow per minute.
e. vascular smooth muscle response to hypoxia.
69. Which of the following situations would be expected to decrease pulmonary
vascular resistance?
a. moderate exercise
b. inspiration to total lung capacity
c. expiration to residual volume
d. ascent to 15,000 feet above sea level
e. all of the above
70. Which of the following factors help keep the alveoli free of fluid ("dry"), thus
protecting the lungs from pulmonary edema?
a. low pulmonary capillary blood pressure (PC) as compared to plasma oncotic pressure (p pl)
b. an efficient system of drainage via pulmonary lymphatics
c. movement of water and solutes from pulmonary capillaries into the interstitial space
d. a and b
e. a, b, and c
71. In a patient with severe interstitial fibrosis of the lung, all of the following
factors are likely to contribute to the hypoxemia during exercise EXCEPT:
a. increased alveolar ventilation.
b. reduced time spent by the blood in the pulmonary capillary.
c. ventilation-perfusion inequality.
d. thickening of the blood-gas barrier.
72. In peripheral capillaries, more O2 can be unloaded from blood at a given PO2
when:
a. blood temperature is reduced.
b. PCO2 is raised.
c. blood pH is raised.
d. the concentration of 2,3-DPG in the red blood cell is reduced.
73. CO2 is carried in the blood mostly as:
a. bicarbonate ions in red blood cells.
b. dissolved CO2.
c. carbamino Hb.
d. bicarbonate ions in the plasma.
e. carbamino compounds with plasma proteins.
74. A blood sample was taken from the brachial artery of a patient admitted to
the hospital complaining of shortness of breath. His arterial PO2 is 50 mmHg,
arterial pH is 7.4, and [Hb] is 13.2 grams/100 ml blood. Using the HbO2
dissociation curve provided above, what are the arterial percent saturation of Hb
and arterial oxygen content (disregard O2 in solution) for this patient?
a. 50%; 8.8 ml O2 /100 ml blood
b. 50%; 17.7 ml O2 /100 ml blood
c. 85%; 8.8 ml O2 /100 ml blood
d. 85%; 15.0 ml O2 /100 ml blood
e. 85%; 17.7 ml O2 /100 ml blood
75. The apex, compared with the base, of the upright lung:
a. has smaller alveoli.
b. has a higher PO2 .
c. has a higher PCO2 .
d. is underventilated relative to its perfusion.
e. has a low ventilation-perfusion ratio.
76. Hypoxemia due to an intrapulmonary shunt cannot be corrected by giving the
patient 100% O2 to breathe because:
a. the amount of O2 physically dissolved in solution does not increase.
b. the shunted blood only comes in contact with poorly ventilated or unventilated alveoli.
c. the shunted blood bypasses ventilated alveoli and is therefore never exposed to the higher alveolar PO2.
d. the time spent by the blood in the pulmonary capillary is insufficient for complete transfer of O2.
77. What is the most common cause of hypoxemia in patients with chronic
obstructive pulmonary disease?
a. hypoventilation
b. diffusion impairment
c. intrapulmonary shunt
d. ventilation-perfusion mismatch
78. Spontaneous respiration ceases after:
a. transection of the brainstem above the pons.
b. transection of the brainstem between the pons and medulla.
c. transection of the brainstem at the caudal end of the medulla.
d. bilateral vagotomy.
e. bilateral vagotomy combined with transection of the brainstem above the pons.
79. Voluntary apnea for 120 seconds will:
a. reduce alveolar PO2.
b. increase alveolar PCO2.
c. decrease arterial pH.
d. stimulate both the arterial and central chemoreceptors.
e. all of the above
80. Based on the information on the graph above, which of the following best describes the tubular handling of the substance? Assume it is freely filtered and not metabolized in the kidney.
a. no net tubular transport
b. net secretion
c. net reabsorption
d. Both secretion and reabsorption occur.
81. Again using the graph above (on page 13), what is Tm of the substance?
a. There is no apparent Tm for the substance.
b. 0 mg/min
c. 200 mg/min
d. 100 mg/min
82. A person is infused with PAH and, after equilibration, PPAH is 0.01 mg/ml. At this time, urine flow is 1 ml/min and UPAH is 5 mg/ml. If the hematocrit is 0.5, what is the renal blood flow?
a. 200 ml/min
b. 500 ml/min
c. 1 liter/min
d. None of the above are correct.
83. A person has an arterial PCO2 of 31 mmHg, and plasma [bicarbonate] of 14 mM. What is plasma pH?
a. 7.19
b. 7.28
c. 7.52
d. None of the above are within 0.05 pH units from the correct pH.
84. A person has a plasma pH of 7.60, plasma bicarbonate concentration of 20 mM, and arterial PCO2 of 21 mmHg. How would you describe the acid base status of this person?
a. respiratory alkalosis
b. respiratory acidosis
c. metabolic alkalosis
d. metabolic acidosis
85. Which of the following mechanisms is NOT INVOLVED in sodium reabsorption in the thick ascending limb?
a. passive sodium diffusion through apical membrane sodium channels
b. passive sodium diffusion through the tight junctions
c. active extrusion of sodium from the cell via Na,K-ATPase located in the
basolateral membrane
d. a, b, and c all contribute significantly to sodium transport.
86. Which of the following statements about body fluid compartments is true?
a. Extracellular fluid sodium and chloride concentrations are equal.
b. The interstitial fluid is included in the intracellular fluid compartment.
c. The volume of red cells in blood is included in extracellular fluid volume.
d. Inulin can be used to measure extracellular fluid volume.
87. Which of the following will expand extracellular fluid volume while not greatly altering intracellular fluid volume?
a. severe sweating
b. ingestion of 2 liters of pure water
c. ingestion of 2 liters of isotonic sodium chloride solution
d. none of the above
88. Which of the following statements about renal medullary countercurrent multiplication is FALSE?
a. The high concentrations of sodium and chloride in the medullary interstitium result from the reabsorption of these ions by the cells of the ascending limbs.
b. In the descending vasa recta, solutes diffuse into the blood from the interstitium.
c. The distal tubule and outer medullary collecting ducts are not permeable to urea.
d. In a water diuresis, the tubular fluid entering the outer medullary collecting ducts will be isotonic with respect to plasma.
89. Which of the following statements about the renal response to a rise in plasma PCO2 is FALSE?
a. Renal tubular H+ secretion and renal production of bicarbonate will increase.
b. Inhibition of cytosolic carbonic anhydrase will blunt the renal response to the excess CO2.
c. Plasma bicarbonate will buffer the excess H+.
d. K+ secretion may decrease somewhat.
90. Which of the following statements about the cells of the collecting ducts is FALSE?
a. Intercalated cells secrete H+ into the tubular fluid.
b. ADH stimulates the insertion of water channels into the apical membrane of principal cells.
c. H+ are secreted into the tubular lumen by a H+-ATPase.
d. About half of the sodium ions reabsorbed diffuse through the tight junctions.