HBY 531 Organ Systems
Mid-Term Examination
1999
Section 1: Answer the following using:
A = becomes more negative
B = remains unchanged
C = becomes more positive
1. The maximum diastolic potential of a Purkinje fiber __________ when the extracellular potassium concentration in the tissue bath is lowered from 10 to 5 mM.
2. The overshoot of the Purkinje fiber action potential __________ when the bathing calcium concentration is raised from 1.8 to 2.8 mM.
3. The maximum diastolic potential in the sinus node __________ when a b agonist is added to the perfusing solution.
Section 2: Answer the following using:
A = increases
B = no change, or remains unchanged
C = decreases
4. The duration of the T-wave __________ when the action potential at the endocardial base lengthens by 30 msec, and no other changes occur.
5. The slope of phase 4 (diastolic depolarization) __________ when the vagus nerve is stimulated.
6. The strength of contraction in a ventricular myocyte __________ when the intracellular [Na+] is raised from 6 to 8 mM due to Na+/K+ pump blockade.
7. The duration of the P wave __________ when the conduction velocity in the Purkinje fiber is decreased.
8. The conduction velocity of a Purkinje fiber __________when the extracellular [K+] is reduced from 5 to 1 mM.
9. The duration of the QRS complex __________when the rate of repolarization in the Purkinje fibers is increased.
10. Total peripheral resistance ___________ following infusion of a therapeutic dose of epinephrine in the presence of a non-specific a adrenergic antagonist.
11. The rate of acetylcholine synthesis within nerve terminals __________ in the presence of hemicholinium.
12. A decrease in the arterial compliance of the aorta will result in __________ in pulse pressure.
13. Blood flow through the systemic circulation __________ as the hematocrit is raised from 0.40 to 0.65.
14. Phosphorylation of myosin light chain kinase within vascular smooth muscle cells ____________ upon activation of phospholipase C.
15. The intracellular Ca2+ concentration within vascular smooth muscle cells ________ after opening of voltage-gated chloride channels.
16. The ultrafiltration of fluid from the capillaries into the intercellular space _________ as the tissue hydrostatic pressure increases.
17. Capillary hydrostatic pressure _________ after an increase in carotid sinus pressure.
18. During inspiration, the volume inside of the thorax producing a more negative intrapleural pressure.
19. At low lung volumes, expiratory flow (as measured on an expiratory flow-volume curve) __________ with increasing expiratory effort.
20. During an operation, the arterial PCO2 of an anesthetized patient is monitored. The patient is being ventilated by a mechanical ventilator, and the initial value is normal (PCO2 = 40 mmHg). If the ventilation is decreased, PCO2 __________.
21. As pulmonary arterial pressure is increased, pulmonary vascular resistance __________.
22. The relative amount of lung functioning under "Zone 1" conditions _________ as a result of blood loss (hemorrhage) secondary to trauma.
23. The Haldane effect demonstrates that increased O2 saturation (i.e., high PO2) shifts the CO2 dissociation curve to the right, at which point, the CO2 content of the blood __________.
24. An otherwise normal person accidentally aspirates a foreign body into the right main stem bronchus, partially occluding it. As a result, blood flow to the right lung .
25. A patient with congenital heart disease has a right-to-left shunt and an arterial PO2 of 60 mmHg during air breathing. The arterial PO2 __________ when he is given 100% O2.
26. High levels of CO2 __________ the ventilatory response to a constant hypoxic stimulus.
27. Ventilation __________ after the stimulation of slowly adapting pulmonary stretch receptors (i.e., Hering-Breuer inflation receptors).
Section 3: For each of the following, choose the single best response.
28. Which of the following agents will potentiate (i.e. enhance) norepinephrine release from stimulated postganglionic sympathetic nerve terminals?
a. a methyl tyrosine
b. An a 2 adrenergic receptor antagonist.
c. Hemicholinium
d. Tetrodotoxon (TTX)
e. Reserpine
29. Treatment with a cholinesterase inhibitor might be warranted for a patient suffering from acute intoxication to which of the following?
a. A Ca2+ ionophore
b. Succinylcholine
c. Cocaine
d. Tubocurarine
e. A monoamine oxidase (MAO) inhibitor
30. The figure above shows pressure-volume loops from a normal individual (a,b,c,d) and from a patient (a’,b’,c’,d’). Which of the following statements is NOT true?
a. The patient’s systolic pressure is between 140-160 mmHg.
b. The patient’s diastolic pressure is about 80 mmHg.
c. The patient’s pressure-volume work is more than twice that of the normal subject.
d. The patient’s end-diastolic ventricular pressure is almost the same as the normal subject.
e. In the patient, the second heart sound occurs close to c’.
31. Again refering to the figure above, the patient’s condition is most likely due to:
a. excessive sympathetic stimulation.
b. a leaky aortic valve (aortic regurgitation).
c. a leaky mitral valve (mitral insufficiency).
d. left ventricular failure.
e. abnormal functioning of the carotid sinus baroreceptors.
32. The figure above was obtained from a patient. The most probable cause for the abnormal record is:
a. a narrowing (stenosis) of the aortic valve.
b. a leaky aortic valve (aortic regurgitation).
c. a leaky mitral valve (mitral insufficiency).
d. left ventricular failure.
e. abnormal functioning of the carotid sinus baroreceptors.
33. Again referring to the figure above, which of the following statements is NOT true?
a. The heart rate is about 75/min.
b. The mean aortic pressure is 100 mmHg.
c. End diastolic volume will be abnormally high in this patient.
d. The systolic blood pressure is about 240 mmHg.
e. The ECG is normal.
34. Referring to the pressure-volume loops shown above, a’,b’c’d’ is from a patient. The patient’s heart rate is 100/min. The patient’s cardiac output is closest to:
a. 8 L/min.
b. 6 L/min.
c. 5 L/min.
d. 3 L/min.
e. 1 L/min.
35. Again referring to the figure above, the patients ejection fraction is closest to:
a. 1.3.
b. 0.8.
c. 0.6.
d. 0.4.
e. 0.2.
36. Referring to the figure above, which was obtained from a patient, which of the following defects is probably responsible for the abnormality?
a. Right ventricular failure
b. A narrowing (stenosis) of the aortic valve
c. A leaky mitral valve (mitral insufficiency
d. Left ventricular failure
e. A narrowing (stenosis) of the mitral valve
37. Again referring to the figure above and using the letters (a,c,x,v,y) on the venous pressure curve as the reference, the maximum velocity of shortening of the sarcomeres in the left ventricle occurs closest to point:
a. a.
b. c.
c. x
d. v.
e. y.
38. This question refers to the venous return (vascular function) curve shown above. Which of the following statements is NOT true?
a. Stimulating the sympathetic supply to the left ventricle would leave the curve unchanged.
b. The maximum output that can be attained is limited by the collapsing of the central veins when the venous pressure is low.
c. Transfusion would shift the curve to the right.
d. Immediately after left ventricular failure, the curve would be shifted to the left.
e. Hemorrhage would shift the curve to the left.
39. This question considers the force-velocity curve that can be obtained for a papillary muscle. Which of the following statements is NOT true?
a. Increasing preload will shift the curve to the right.
b. Increasing preload will not alter the velocity of shortening when there is no afterload.
c. Adding norepinephrine to the bathing solution will increase the velocity of shortening when there is no afterload.
d. Increasing the afterload will decrease the velocity of shortening.
e. The power output reaches a maximum when the afterload is 95% of the weight the muscle can lift.
40. A patient has an O2 consumption of 200 mL/min and a cardiac output of 4 L/min. The arterial blood contains 0.20 mL O2/mL blood. The closest value to the oxygen content of blood from the pulmonary artery is:
a. 0.25 mL O2/mL blood.
b. 0.20 mL O2/mL blood.
c. 0.15 mL O2/mL blood.
d. 0.10 mL O2/mL blood.
e. Cannot be determined from the information given.
41. Which of the following statements is NOT correct?
a. Stimulation of atrial stretch receptors can elicit a reflex increasing heart rate.
b. An excess of circulating thyroid hormone leads to tachycardia.
c. With increased insulin in the blood, there is an increase in the force of cardiac contraction.
d. Stimulation of atrial stretch receptors causes the secretion of acetylcholine from the myocytes of the atrial wall.
e. The phosphorylation of lamban leads to an increase in rate of active Ca2+ uptake into the sarcoplasmic reticulum of cardiac myocytes.
42. A patient was injected with a solution containing 14,000 counts/min of radioactive red blood cells. Following a suitable equilibration period, a 10 mL blood sample was drawn and found to contain 20 counts/min, and a hematocrit of 0.45. A urine sample revealed no radioactivity. This patient’s plasma volume:
a. is approximately 2.85 L.
b. is approximately 3.15 L.
c. is approximately 3.85 L.
d. is approximately 7.0 L.
e. cannot be estimated with the available data.
43. For a patient with a systolic arterial pressure of 125 mmHg, a diastolic arterial pressure of 80 mmHg, and a cardiac output of 5 L/min, what is the total peripheral resistance?
a. 13 mmHg . min/L
b. 15 mmHg . min/L
c. 17 mmHg . min/L
d. 19 mmHg . min/L
e. 21 mmHg . min/L.
44. Blood flow through the left coronary artery virtually ceases during which phase of the cardiac cycle?
a. Isovolumetric contraction
b. The reduced ejection phase
c. Isovolumentric relaxation
d. Rapid ventricular filling
e. Reduced ventricular filling
45. In a normal adult, most of the blood in the circulation is located in:
a. systemic capillaries.
b. systemic veins.
c. pulmonary capillaries.
d. pulmonary veins.
e. systemic arteries and arterioles.
46. Which of the following is NOT expected to increase the level of intracellular calcium in vascular smooth muscle cells?
a. An a adrenergic receptor agonist
b. Depolarization of the membrane
c. A G-protein-mediated increase in guanylyl cyclase activity
d. Angiotensin II
47. When a person lying on a tilt table is shifted from a horizontal to an upright position, the cardiac output decreases because:
a. arterial compliance decreases.
b. central venous pressure decreases.
c. heart rate decreases.
d. sympathetic activity to the heart decreases.
48. In metabolic regulation of blood flow,
a. basal vascular tone is unchanged when tissue metabolism is altered.
b. blood flow is held constant during changes in tissue metabolism.
c. blood flow and tissue metabolism are inversely related.
d. blood flow and arterial pressure are inversely related.
e. blood flow and tissue metabolism are directly related.
49. Compared to young people, the less compliant arterial system in old people:
a. allows blood to flow through the capillaries at a more steady rate.
b. requires the heart to expend more energy to pump a normal cardiac output.
c. prevents the arterial systolic pressure from attaining excessively high values.
d. increases the total blood volume.
e. decreases the mean arterial blood pressure.
50. Which of the following is NOT true of the conducting airways?
a. They contain no alveoli.
b. The walls of the conducting airways are too thick for much diffusion to take place.
c. They take no part in gas exchange and therefore make up the anatomical dead space.
d. All of the above statements are true.
51. At total lung capacity,
a. the elastic recoil of both the lung and chest wall are directed outward.
b. the elastic recoil of both the lung and chest wall are directed inward.
c. the inward directed elastic recoil of the lung is greater than that of the outward directed elastic recoil of the chest wall.
d. the inward directed elastic recoil of the lung balances the outward directed elastic recoil of the chest wall.
52. Lung compliance:
a. is greater at functional residual capacity (FRC) than at total lung capacity (TLC).
b. represents the relationship between changes in the pressure distending the alveoli and the corresponding changes in lung volume.
c. decreases in restrictive pulmonary disease (i.e., pulmonary fibrosis).
d. can only be measured when air is flowing into or out of the lungs.
e. a, b, and c
53. Surfactant:
a. has no effect on maintaining stability of alveolar volumes of different sizes.
b. decreases surface tension independent of lung volume (surface area).
c. 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).
d. ensures relatively even distribution of the ventilation throughout the lung.
54. Airways resistance:
a. is low at low lung volumes.
b. can only be measured when air is flowing into or out of the lungs.
c. is higher in the small airways than in the medium sized bronchi because the small airways are arranged in parallel.
d. decreases during stimulation of the parasympathetic postganglionic fibers innervating the bronchial smooth muscle.
e. is minimized by dynamic compression of the airways.
55. Which of the following factors may reduce the FEV1 in a patient with chronic obstructive pulmonary disease (COPD)?
a. Excessive secretions in the airway
b. Loss in radial traction on the airways
c. Reduction in the number of small airways
d. Loss of elastic recoil in the lung
e. All of the above factors may contribute to reduced FEV1.
56. Which patient has the highest alveolar ventilation?
a. Tidal volume = 200 mL; Frequency = 35 breaths/min; Dead space volume = 200 mL
b. Tidal volume = 500 mL; Frequency = 14 breaths/min; Dead space volume = 200 mL
c. Tidal volume = 1000 mL; Frequency = 7 breaths/min; Dead space volume = 200 mL
d. Alveolar ventilation is the same in all cases.
57. A normal person, seated upright, begins to inspire from functional residual capacity (FRC). The first 100 mL of inspired gas is labeled with xenon 133 (133Xe). After the first inspiration, most of this radioactive gas will probably be found:
a. in the conducting airways (i.e., anatomical dead space).
b. in the alveoli in the upper portions of the lung.
c. in the alveoli in the lower portion of the lung.
d. uniformly distributed to all alveoli.
58. Which of the following circumstances might be expected to contribute to the formation of pulmonary edema?
a. Occlusion of the lymphatic drainage of an area of the lung
b. Destruction of portions of the pulmonary capillary endothelium by toxins
c. High concentrations of plasma proteins
d. Low pulmonary capillary blood pressure (PC) as compared to plasma oncotic pressure (p pl)
e. a and b
59. Which of the following is NOT true regarding diffusion of O2 and CO2 in the lungs?
a. CO2 is approximately 20 times more diffusible than O2.
b. Under normal conditions, diffusion of both O2 and CO2 follow a similar time course.
c. The partial pressure gradient for diffusion of O2 is greater than the partial pressure gradient for diffusion of CO2.
d. The surface area available for diffusion is reduced during exercise due to increased blood flow.
60. Measurement of a patient’s hemoglobin-oxygen dissociation curve showed a marked reduction in the P50. The most likely causative factor is:
a. arterial CO2 retention.
b. an abnormally low concentration of 2,3-DPG in the transfused red blood cells.
c. a reduced arterial pH.
d. an increased blood temperature.
61. CO2 is carried in the blood mostly:
a. dissolved.
b. as carbamino compounds with plasma proteins.
c. as carbamino Hb.
d. as bicarbonate ions in the plasma.
e. as bicarbonate ions in red blood cells.
62. Compared with the base, the apex of the upright lung:
a. has a high PO2.
b. has a high PCO2.
c. has smaller alveoli.
d. is better perfused.
e. has a low ventilation-perfusion ratio.
63. What mechanism is responsible for most, if not all, of the arterial hypoxemia of chronic obstructive pulmonary disease (COPD)?
a. Hypoventilation
b. Diffusion impairment
c. Shunt
d. Ventilation-perfusion inequality
64. During exercise of progressive intensity,
a. minute ventilation and CO2 production rise sharply at "anaerobic threshold".
b. oxygen consumption decreases slightly.
c. blood lactate levels remain constant.
d. increased minute ventilation reduces PCO2 levels.
65. Which of the following factors are most likely to lead to apneic episodes in patients with obstructive sleep apnea syndrome?
a. Increased hypoxic drive during sleep
b. Increased vagal drive during sleep
c. Loss of tone of the genioglossus muscle
d. Chronic sleep deprivation
66. A spinal cord reflex is involved the the process of micturition. Destruction of which of the following nerves will cause complete bladder dysfunction?
a. The pudendal nerves
b. The parasympathetic nerves that innervate the body of the bladder
c. The sympathetic (hypogastric) nerves that innervate the bladder neck and urethra
d. a and b
67. Which of the following statements about renal hemodynamics and glomerular filtration is FALSE?
a. The major resistances in the renal vasculature are the afferent and efferent arterioles.
b. Constriction of the efferent arteriole (all other factors constant) will increase glomerular capillary hydrostatic pressure.
c. Typical values of the hydrostatic pressures within the glomerular capillaries and Bowman’s capsule are 50 mmHg, and 12 mmHg, respectively.
d. The magnitude of the ultrafiltration coefficient, Kf, is not affected by mesangial cell contraction.
68. Which of the following are characteristics of the glomerular filtration barrier?
a. It consists of 2 distinct layers: a basement membrane and a layer of epithelial cells called podocytes.
b. It’s permselectivity properties with respect to plasma proteins are determined primarily by the width of the fenestrations between capillary endothelial cells.
c. It is freely permeable to uncharged solutes with MW less than approximately 5 kD.
d. None of the above are correct.
69. Which of the following statements about autoregulation of RBF and GFR is FALSE?
a. Autoregulation is mediated, in part, by a myogenic reflex intrinsic to vascular smooth muscle.
b. Tubuloglomerular feedback contributes to renal autoregulation by increasing afferent arteriolar resistance when GFR increases and the flow of tubular fluid through Henle’s loop rises.
c. Renal autoregulation does not prevent changes in RBF in response to vasoactive hormones.
d. Renal autoregulation is able to stabilize renal blood flow when mean systemic blood pressure decreases to pressures as low as 40 mmHg.
70. Which of the following cause renal vasoconstriction?
a. Nitric oxide
b. Norepinephrine
c. Prostaglandins (PGE2 and PGI2).
d. Acetylcholine
71. Which of the following is the most important apical membrane transport process that moves sodium into thick ascending limb cells from the tubular fluid?
a. Active sodium transport by Na,K-ATPase
b. Thiazide-inhibitable Na,Cl co-transport
c. Furosemide-inhibitable Na,K,2Cl co-transport
d. Passive diffusion of sodium through sodium channels
72. Which of the following mechanisms is NOT INVOLVED in the reabsorption of sodium by the cells of the proximal tubule?
a. Secondary active transport of glucose and amino acids through the apical membrane
b. Secondary active secretion of protons by H+-Na+ exchange across the apical membrane
c. Passive diffusion of sodium and chloride through the tight junctions
d. Thiazide-inhibitable NaCl co-transport
a. Water reabsorption in the medullary collecting ducts arises because of sodium and chloride reabsorption in the ascending limb of Henle’s loop.
b. In an antiduresis, urea is passively secreted into Henle’s loop and passively reabsorbed in the medullary collecting duct.
c. Solutes diffuse
out of the descending vasa recta and into the ascending vasa recta, a process called passive countercurrent exchange. ..
d. When ADH levels are high, the osmolarity of the tubular fluid at entrance to the medullary collecting ducts is the same as systemic plasma.
74. Which of the following will result in an increase in the volume of extracellular fluid?
a. Increased capillary permeability to plasma protein in a person with normal kidney function.
b. Ingestion of 2 liters of pure water.
c. Ingestion of 300 mmoles of sodium chloride by a person with free access to water.
d. a, b, and c.
75. The action of ADH on the cells of the distal tubule and collecting duct involves which of the following steps?
a. ADH binding to basolateral membrane receptors, with subsequent stimulation of adenylyl cyclase
b. Fusion of cytosolic vesicles with the basolateral membrane
c. cAMP activation of a protein kinase
d. a and c
76. Which of the following changes would occur following inhibition of angiotensin
converting enzyme, assuming that renin levels were elevated before the drug was given?
a. Arterial blood pressure will decrease.
b. Aldosterone levels in plasma will fall.
c. Proximal tubular sodium reabsorption will decrease.
d. All of the above are correct.
77. A person loses 1 liter of isotonic fluid because of diarrhea. Which of the following statements about the responses to this loss is FALSE?
a. The osmolarity of the extracellular fluid will be unchanged, but extracellular fluid volume will be decreased.
b. Sympathetic activity will rise, and the filtration fraction of the kidney will increase.
c. Elevated angiotensin II levels will depress vasodilatory prostaglandin production by the renal vasculature.
d. Atrial natriuretic peptide secretion will be reduced.
78. Regarding the regulation of renal sodium excretion, which of the following is TRUE?
a. The distal afferent arteriole acts as a baroreceptor, in that renin secretion rises when intravascular pressure in this segment falls.
b. Angiotensin II depresses aldosterone release from the adrenals.
c. Renin secretion can be stimulated by a large increase in tubular fluid flow past the macula densa.
d. Atrial natriuretic peptide reduces sodium excretion by constricting the afferent arterioles.
79. The cellular actions of aldosterone in the distal tubule and collecting ducts include which of the following?
a. Binding to a membrane-bound receptor located on the basolateral membrane
b. Induction of synthesis of sodium channels, potassium channels, and Na,K-ATPase
c. Activation adenylyl cyclase
d. a and b
80. Which of the following IS NOT an action of atrial natriuretic peptide?
a. Inhibition of ADH secretion
b. Stimulation of renin secretion
c. Peripheral vasodilation
d. Inhibition of inner medullary collecting duct sodium reabsorption
81. Which of the following statements about potassium is FALSE?
a. Most of the potassium filtered in the glomerulus is reabsorbed by the proximal tubule.
b. With normal K+ intake, a rise in tubular fluid flow in the distal tubule and collecting ducts will tend to increase potassium excretion, except when the rise in flow is associated with a fall in ADH levels.
c. A fall in plasma pH will tend to decrease the plasma K+ concentration.
d. Potassium depletion may be a consequence of diuretic therapy.
82. Which of the following statements about potassium is FALSE?
a. A reduction in dietary K+ intake will tend to reduce plasma [K+].
b. In times of body K+ depletion, there is net reabsorption of K+ in the distal tubules and collecting ducts.
c. A fall in the plasma [K+] stimulates aldosterone release from the adrenal cortex.
d. Potassium secretion across the apical membrane in principal cells involves only passive diffusion.
83. Which of the following statements about renal epithelial H+ secretion is CORRECT?
a. H+ secretion will rise when either plasma bicarbonate concentration falls or plasma PCO2 rises.
b. H+ secretion will be decreased by inhibition of cytosolic carbonic anhydrase.
c. H+ secretion into the lumen of the proximal tubule reduces tubular fluid bicarbonate concentration.
d. All of the above are correct.
84. Regarding renal acid-base handling, which of the following statements is FALSE?
a. The prime role of the kidney is to excrete protons and to regulate plasma bicarbonate levels.
b. Ammonium ion excretion is reduced in a metabolic acidosis.
c. For each H+ secreted into the tubular fluid, a bicarbonate molecule is released into the plasma.
d. In a metabolic alkalosis, renal H+ secretion is reduced and some of the filtered bicarbonate is excreted.
The following two questions use the figure on the right which
shows the filtered load and excretion rate of substance X in a child.
85. Which of the following best describes the renal handling of substance X? Assume X is freely filtered and not metabolized in the kidney.
a. No net tubular transport.
b. Net secretion
c. Net reabsorption
d. There is not enough information to determine anything about tubular transport.
86. What is the Tm of substance X?
a. There is no apparent Tm for substance X.
b. 100 µg/min
c. 50 mL/min
d. 2 µg/mL
87. A person has a Hct of 0.5, renal blood flow of 1 liter/min, and a filtration fraction of 0.25. What is the persons GFR?
a. 100 mL/min
b. 125 mL/min
c. 200 mL/min
d. None of the above are correct.
88. An otherwise healthy person’s urine flow is 2 liters/day, and the urine contains 20 mM HCO3- with pH > 7.4. What can you conclude about this person’s acid-base status?
a. The person has a metabolic acidosis.
b. The person has a metabolic alkalosis.
c. The person has a respiratory alkalosis.
d. The person is probably alkalotic, but the information is insufficient to decide if it is metabolic or respiratory.
89. A person has an arterial PCO2 of 60 mmHg and [HCO3-] of 29 mM. Which of the following is closest to the person’s plasma pH?
a. 7.2
b. 7.3
c. 7.5
d. 7.6
90. A person has an arterial PCO2 of 65 mmHg, [HCO3-] of 26 mM, and a pH of 7.22. Which of the following acid-base disturbances is most consistent with these values?
a. Respiratory alkalosis
b. Metabolic alkalosis
c. Respiratory acidosis
d. Metabolic acidosis