HBY 531 Organ Systems
Mid-Term Examination
1998
Section 1: Answer the following using:
A = becomes more negative
B = remains unchanged
C = becomes more positive
1. The maximum diastolic potential___________ when a beta agonist is applied to the SA node.
2. The maximum diastolic potential of the SA node____________ when the vagus nerve is
stimulated.
Section 2: Answer the following using:
A = increases
B = remains unchanged
C = decreases
3. The duration of the Purkinje fiber action potential ________ when the L-type calcium current is increased.
4. The conduction velocity in the SA node _________ after 1 micromolar TTX is applied.
5. The duration of the P wave __________ when the conduction velocity in the Purkinje fiber is decreased.
6. The heart rate __________ when the duration of the Purkinje fiber action potential is prolonged.
7. The slope of diastolic depolarization __________ when a beta agonist is applied.
8. The R-R interval of the EKG __________ when the vagus nerve is stimulated.
9. The amplitude of the T-type calcium current in the SA node__________ when a beta agonist is applied.
10. The force of myocardial contraction__________ due to increased heart rate.
11. Heart rate___________ due to hypervolemia.
12. The release of atrial natriuretic peptide (ANP) _________ due to hypovolemia.
13. Circulating angiotensin II ____________ upon administration of angiotensin converting enzyme (ACE) inhibitors.
14. The myocardial force of contraction___________ upon administration of calcium channel
blockers.
15. Blood flow through coronary arteries____________ due to increased levels of nitric oxide.
16. For air to flow into the lungs, the alveolar transmural pressure gradient __________.
17. Functional residual capacity in patients with obstructive pulmonary disorders
(i.e., emphysema).
18. When CO2 production is held constant, PaCO2 ___________ during hyperventilation.
19. Blood flow in Zone 1 of the upright lung after lowering pulmonary arterial or
pulmonary venous pressure.
20. The affinity of hemoglobin for oxygen __________ when concentrations of 2,3-DPG
increase (which shifts the hemoglobin-oxygen dissociation curve to the right).
21. Poorly ventilated alveoli have low ventilation-perfusion ratios which leads to regional hypoxia
(low PO2). Pulmonary arteriolar diameter and blood flow __________ in an attempt to return the
ventilation-perfusion ratio to normal.
22. Net reabsorption by the proximal tubule __________ after an increase in renal sympathetic nerve activity.
23. The net reabsorptive pressure across the walls of peritubular capillaries ____________when
filtration fraction is increased.
24. Angiotensin I production in plasma _____________ after an increase in flow in Henle's loop.
25. During hypovolumia, renal vascular resistance _____________ after inhibition of ACE.
26. Filtration fraction _____________ after a rise in afferent arteriolar resistance.
27. Efferent arteriolar resistance ______________ after a 20 mm Hg rise in systemic arterial blood pressure above normal levels.
28. Sodium reabsorption in collecting ducts ______________ after a rise in urodilantin release.
29. Adrenal aldosterone secretion _______________ as a consequence of a rise in plasma ANP levels.
30. Prostaglandin production by the renal arterial system ____________ after a decrease in plasma angiotensin II levels.
31. K+ secretion in distal tubule and collecting ducts _____________ upon administration of
furosemide.
32. The density of Na,K-ATPase in collecting duct cells _______________ after a fall in plasma
aldosterone levels.
33. K+ secretion in distal tubule _______________ after an increase in the plasma ADH concentration.
34. Plasma bicarbonate concentration ______________ to compensate for respiratory alkalosis.
Section 3: For each of the following, choose the single best response.
35. Which of the following statements about an isolated papillary muscle studied in a device for measuring isotonic contraction is FALSE?
a. The maximum afterload that can be lifted is increased by raising the preload.
b. Applying norepinephrine will increase the initial velocity of the contraction.
c. Increasing the afterload will increase the maximum power the muscle can generate.
d. The maximum power the muscle can generate is highest at the fastest velocity of contraction.
e. Increasing the afterload can bring the velocity to zero.
36. Regarding a cardiac muscle sarcomere,
a. the Z line runs through the center of the thick filament.
b. the thin filament has a binding site for norepinephrine.
c. the thin filaments are held in position by titan.
d. the triggering Ca2+ binds to troponin C on the thin filament.
e. whenever the length of the sarcomere is shortened, the overlap between thick and thin filaments is optimized so that the force of contraction always increases.
37. When a cardiac myocyte is exposed to norepinephrine,
a. the duration of the action potential is lengthened.
b. titan becomes more elastic.
c. lamban is dephosphorylated.
d. the rate of Ca2+ transport into the sarcoplasmic reticulum is increased.
e. the rate of lactic acid-release from the cell is increased.
38. During the cardiac cycle which of the following pairs of events DO NOT occur at the same time?
a. Ventricular contraction and the C wave of the venous pulse
b. Atrial contraction and the A wave of the venous pulse
c. The back flow of blood in the aorta toward the heart and the incisura (=dicrotic notch)
d. Peak flow rate from the ventricle into the aorta and systolic pressure
e. Closing of the aortic valve and the third heart sound
39. The work performed by the left ventricle is substantially greater than that performed by the right ventricle because in the left ventricle,
a. the stroke volume is greater.
b. the preload is greater.
c. the afterload is greater.
d. the wall is thinner.
e. the contraction is slower.
40. The diagram above shows pressure records from the aorta, the left ventricle, and the left atrium of a patient. The abnormality in the record could be accounted for
a. by a narrowing (stenosis) of the aortic valve.
b. by a narrowing of the mitral valve.
c. by regurgitation from the aorta to the left ventricle through a defective aortic valve.
d. by regurgitation from the left ventricle to the left atrium through a defective mitral valve.
e. by a massive increase in sympathetic outflow.
41. In the same diagram, the mean aortic pressure is closest to
a. 90 mm Hg.
b. 100 mm Hg.
c. 120 mm Hg.
d. 140 mm Hg.
e. 240 mm Hg.
42. In a subject on a treadmill the heart rate is 100 beats/min, the O2 uptake is 300 mL/min, the blood in the pulmonary artery contains 0.16 mL O2/mL and the blood in the pulmonary vein contains 0.21 mL O2/mL. What is the subject’s stroke volume?
a. 0.04 L
b. 0.05 L
c. 0.06 L
d. 0.08 L
e. 5 L
43. In the work loop shown above, the aortic valve closes at
44. In the work loop shown above the ejection fraction is closest to:
a. 0.75.
b. 0.67.
c. 0.55.
d. 0.47.
e. 0.33.
45. A subject with a denervated carotid sinus will exhibit which of the following general characteristics?
a. Chronic hypertension
b. Chronic hypotension
c. An inability to exercise
d. A markedly decreased cardiac output
e. An abnormally variable mean aortic pressure
46. Immediately following damage to a part of the ventricular muscle,
a. the vascular function curve will be shifted upward.
b. the vascular function curve will be shifted downward.
c. the ventricular function curve will be shifted upward.
d. the ventricular function curve will be shifted downward.
e. neither the vascular nor ventricular function curve will be altered.
47. A few days following moderate heart failure,
a. the central venous pressure will be elevated.
b. the central venous pressure will be lowered.
c. the cardiac output will be low.
d. the blood volume will be decreased.
e. the carotid sinus will cease operating.
48. From Poiseuille’s Law, vasoconstriction of blood vessels perfusing an organ sufficiently to
cause vessel diameter to be halved, blood flow will
a. increase 2 fold.
b. decrease 2 fold.
c. decrease 8 fold.
d. decrease 16 fold.
49. Increased firing in Hering’s nerve would
a. enhance efferent vagal nerve impulses to the heart.
b. enhance efferent sympathetic nerve stimulation to the peripheral vasculature.
c. result from decreased blood volume.
d. increase afferent vagal impulses from the aortic arch.
50. Which of the following would lead to increased lymph production (Pc = capillary hydrostatic
pressure; Pi, interstitial fluid hydrostatic pressure; pc, oncotic pressure of plasma; pi oncotic
pressure of interstitial fluid)?
a. An increase in pc
b. An increase in Pi
c. An increase in Pc
d. A decrease in pi
51. "Pressure autoregulation" denotes which sequence of events?
a. ¯ mean arterial pressure® ¯ blood flow® adenosine and CO2 formation® vasodilation® blood flow
b. blood flow® tissue metabolic activity® adenosine and CO2 formation® vasoconstriction
c. tissue metabolic activity® adenosine and CO2 formation® vasodilation® blood flow
d. vasodilation® ¯ blood flow
52. Which of the following statements is FALSE?
a. An increase or decrease in blood volume will result in increased heart rate.
b. Increased heart rate results in increased force of myocardial contraction.
c. Perfusion of carotid chemoreceptors with blood containing low oxygen will cause a more rapid heart beat.
d. Clamping of the common carotid arteries below the carotid sinus will result in decreased firing of nerves eminating from the baroreceptors.
53. What effect(s) will occur when the hematocrit increases appreciably?
a. An increase in turbulent flow
b. A decrease in the resistance to blood flow
c. An increase in laminar flow
d. b and c
54. Compared to systemic arterioles, systemic venules
a. are more compliant.
b. have a higher vascular resistance per unit length.
c. normally contain the same percentage of body blood volume.
d. a and c
55. Regarding blood flow through the cerebral vasculature,
a. the blood flow fluctuates with increasing and decreasing mean systemic arterial pressures.
b. blood flow is heavily regulated by sympathetic and parasympathetic fibers.
c. adenosine causes vasoconstriction and a resulting decrease in blood flow.
d. CO2 causes vasodilation which results in an increase in blood flow.
56. In response to a substantial hemorrhage,
a. the neural activity of the efferent vagus to the heart decreases.
b. the neural activity in the carotid sinus baroreceptor nerve fibers increases.
c. the neural activity of the efferent sympathetic nerve fibers to the heart decreases.
d. the release of vasopressin (ADH) from the posterior pituitary gland decreases.
57. Which of the following hormones, when infused into a patient, will reduce edema?
a. Angiotensin II
b. ADH
c. ANP
d. Aldosterone
58. Intrapleural pressure is most negative at
a. the end of a tidal breath.
b. total lung capacity.
c. functional residual capacity.
d. residual volume.
59. During a pneumothorax,
a. the volume of the thoracic cavity increases.
b. the volume of the lung increases.
c. the elastic recoil forces of the lung and the chest wall are equal but opposite.
d. the intrapleural pressure becomes more negative.
e. a and c
60. Lung compliance
a. is determined by the slope between two points on the pressure-volume curve.
b. denotes the ease with which the lung parenchyma can be stretched.
c. is defined as the change in lung volume divided by the change in the transpulmonary pressure.
d. depends upon the elastic properties of the lungs and chest wall as well as surface tension forces.
e. a, b, and c.
61. Which of the following helps prevent alveolar collapse during expiration?
a. Surface tension at the air-liquid interface
b. The relatively even distribution of ventilation throughout the lung
c. Structural interdependence of the alveoli
d. The small alveolar surface area
e. Dynamic compression of the airways
62. Which of the following statements concerning small airways is (are) true?
a. The total resistance to airflow decreases with successive generations of airways because there are increasing numbers of units arranged in parallel.
b. The linear velocity of airflow decreases as the airways decrease in size because their total cross-sectional area increases.
c. Airflow is usually laminar.
d. All of the above are true.
63. Airways resistance is extremely high at low lung volumes because
a. bronchial smooth muscle actively contracts at low lung volumes.
b. intrapleural pressure becomes positive.
c. alveolar elastic recoil is higher at low lung volumes than it is at high lung volumes.
d. the pressure gradient for airflow is greater at low lung volumes than it is at high lung volumes.
e. alveolar PCO2 increases.
64. The volume of gas in the lungs at any instant in time depends upon the
a. mechanics of the lung.
b. mechanics of the chest wall.
c. mass of the lungs.
d. activity of the inspiratory and expiratory muscles.
e. a, b, and d
65. A 150 lb. patient has a vital capacity of 6 L, a functional residual capacity of 3 L, and a total
minute ventilation of 8 L/min. He is breathing at a rate of 10 breaths per minute. His tidal
volume is:
a. 200 mL.
b. 300 mL.
c. 500 mL.
d. 600 mL.
e. 800 mL.
66. Which patient has the highest alveolar ventilation?
a. Tidal volume = 150 mL; Frequency = 40 breaths/min; Dead space volume = 150 mL
b. Tidal volume = 500 mL; Frequency = 12 breaths/min; Dead space volume = 150 mL
c. Tidal volume = 1000 mL; Frequency = 6 breaths/min; Dead space volume = 150 mL
d. Alveolar ventilation is the same in all cases.
67. Which of the following situations would be expected to increase pulmonary vascular
resistance?
a. Inspiration to total lung capacity
b. Expiration to residual volume
c. Increased pulmonary arterial pressure or pulmonary venous pressure
d. a and b
e. a, b, and c
68. Which of the following has the greatest effect on the ability of blood to transport oxygen?
a. Solubility of oxygen in the plasma
b. Amount of hemoglobin in the blood
c. Carbon dioxide content of the red blood cells
d. pH of the plasma
e. Temperature of the blood
69. An otherwise normal person has lost enough blood to decrease his/her body’s hemoglobin
concentration from 15 g/100 mL blood to 12 g/100 mL blood. Which of the following would be
expected to decrease?
a. Arterial PO2
b. Oxygen carrying capacity of the blood
c. Arterial hemoglobin saturation
d. Arterial oxygen content
e. b and d
70. With respect to oxygen and carbon dioxide transport,
a. the slope of the hemoglobin-oxygen dissociation curve is similar to the slope of the carbon dioxide dissociation curve.
b. increased carbon dioxide favors oxygen binding to hemoglobin.
c. increased oxygen lowers the carbon dioxide content of the blood.
d. b and c
e. a, b, and c
71. A normal person lies down on his/her left side and breathes normally. His/her left lung, in
comparison to his/her right lung, would be expected to have
a. larger alveoli.
b. lower alveolar PO2 and higher alveolar PCO2.
c. lower ventilation per unit volume.
d. lower blood flow per unit volume.
e. higher ventilation-perfusion ratio.
72. A patient’s PaCO2 is 70 mmHg, the PaO2 is 50 mmHg, and the alveolar-arteriolar O2 gradient is normal. These findings are consistent with
a. a generalized hypoventilation.
b. a diffusion impairment.
c. an intrapulmonary shunt.
d. a ventilation-perfusion mismatch.
73. A patient in the emergency room has a PaCO2 of 38 mmHg and a PaO2 of 50 mmHg.
Following administration of 100% oxygen, you find that his/her PO2 remains unchanged. These
findings are consistent with
a. a generalized hypoventilation.
b. a diffusion impairment.
c. an intrapulmonary shunt.
d. a ventilation-perfusion mismatch.
74. Which of the following patterns of breathing is seen when the brainstem is intact and the vagus nerves are cut bilaterally?
a. A decrease in both the depth and rate of breathing
b. An increase in both the depth and rate of breathing
c. A decrease in depth of breathing accompanied by an increase in rate
d. An increase in depth of breathing accompanied by a decrease in rate
e. Both increases and decreases in depth of breathing with no change in rate
75. Variations in which of the following components of blood or cerebrospinal fluid DO NOT
affect respiration?
a. Arterial CO2 concentration
b. Arterial H+ concentration
c. Arterial Na+ concentration
d. Cerebrospinal fluid CO2 concentration
e. Cerebrospinal fluid H+ concentration
76. Which of the following factors may contribute to the impaired ventilatory response to inhaled
CO2 in a patient with chronic obstructive pulmonary disease (i.e., emphysema, chronic
bronchitis)?
a. Reduced neural output of the respiratory centers
b. Increased compliance of the chest wall
c. Arterial hypoxemia
d. Increased airways resistance
e. Increased diffusing capacity
77. 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
78. Again using the graph above, what is the 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
79. A person is infused with inulin at a constant rate of 1 mg/min. After equilibration, the plasma
inulin concentration is 0.02 mg/mL. What is the person’s GFR?
a. 1 mg/min
b. 100 ml/min
c. 50 ml/min
d. None of the above are correct.
80. A person has an arterial PCO2 of 61 mmHg, and plasma [bicarbonate] of 24 mM. What is
plasma pH?
a. 7.22
b. 6.11
c. 7.63
d. None of the above are within 0.05 pH units from the correct pH.
81. A person has a plasma pH of 7.62, a plasma bicarbonate concentration of 40 mM, and an
arterial PCO2 of 42 mmHg. How would you describe the acid base status of this person?
a. Respiratory alkalosis
b. Respiratory acidosis
c. Metabolic alkalosis
d. Metabolic acidosis
82. A person has a urine flow of 1.25 liters/day. The urine bicarbonate concentration is 2 mM,
the urine titratable acidity is 5 mM, and the urine ammonium concentration is 5 mM. What is the
rate of urinary acid excretion?
a. 12 mmoles/day
b. 10 mmoles/day
c. 8 mmoles/day
d. None of the above are correct.
83. Which of the following mechanisms is NOT SIGNIFICANTLY INVOLVED in sodium
reabsorption in collecting duct principal cells?
a. Passive sodium diffusion through apical membrane sodium channels
b. Passive potassium diffusion through channels in the basolateral membrane
c. Secondary active transport of potassium across the apical membrane
d. a, b, and c all contribute significantly to sodium transport
84. A person ingests 2 liters of pure water. What effect will this have on the volume of the
intracellular and extracellular fluid compartments (ignore the renal responses)?
a. The extracellular compartment will expand, while intracellular volume will be unchanged.
b. The volume of both compartments will expand.
c. Intracellular fluid volume will expand, while extracellular volume will be unchanged.
d. None of the above are correct.
85. Which of the following statements about the renal medullary countercurrent systems is
FALSE?
a. The concentrations of sodium and chloride in descending limbs rise mainly because of the rapid diffusion of both ions into the tubular fluid from the medullary interstitium.
b. In the vasa recta, solutes diffuse out of ascending vessels and into descending vessels.
c. The fluid that enters the outer medullary collecting ducts from the cortical collecting ducts is isosmotic with respect to plasma when ADH levels are high.
d. In a water diuresis, the interstitial osmolarity in the inner medulla will decrease, in part because urea is "washed out" of the medulla when ADH levels are low.
86. Which of the following statements about the responses to a rise in plasma pH during
metabolic alkalosis is FALSE?
a. The filtered load of bicarbonate is elevated.
b. The rate of titratable acid excretion will increase.
c. Renal production of ammonia from glutamine will decrease.
d. Pulmonary ventilation will decrease.
87. Which of the following statements about the proximal tubule is FALSE?
a. When filtration fraction decreases, the back-leak of solutes and water through the tight junctions rises.
b. Sodium entry into the cells through the apical membrane is linked to the filtered load of glucose and amino acids.
c. H+ are secreted into the tubular lumen primarily by a H+-ATPase.
d. Net sodium and water reabsorption is stimulated by angiotensin II.
88. Which of the following nerves is essential for the micturition reflex?
a. Pudendal motor nerves
b. Hypogastric sympathetic nerves
c. Pelvic parasympathetic nerves
d. All of the above are essential.
89. Activation of a 2 - adrenergic receptors on axon terminals of postganglionic sympathetic motor neurons will:
a. stimulate the phosphorylation of tyrosine hydroxylase, thereby activating this enzyme.
b. decrease the rate of uptake of dopamine into synaptic vesicles.
c. decrease the rate of exocytosis of synaptic vesicles into the synaptic cleft.
d. decrease the rate of uptake 1 by inhibiting the monoamine transporter.
90. Which of the following will increase the duration cholinergic stimulation of an effector cell?
a. Botulin toxin
b. Vesamicol
c. Blocking the choline transporter
d. An acetylcholine esterase inhibitor