HBY 531 MEDICAL PHYSIOLOGY

Lecture Exam 2 Version 1

2002

 

 

 

Section 1:  Answer the following using:

 

A = becomes more negative

B = remains the same

C = becomes more positive

 

1.      The maximum diastolic potential of a Purkinje fiber _____C_____ when the external [K+] is reduced from 4mM to 1mM.

 

2.      The maximum diastolic potential of a sinus node myocyte _____A_____ when the vagus nerve is stimulated.

 

3.      The maximum diastolic potential of a sinus node myocyte _____A_____ when perfused with norepinephrine.

 

4.      The overshoot of the sinus node action potential _____B_____ when perfused with TTX.

 

5.      The overshoot of the Purkinje fiber action potential _____A_____ when the external [Na+] is reduced by equimolar substitution with choline.

 

Section 2:  Answer the following using:

 

A = increase(s)

B = (does) not change

C = decrease(s)

 

6.      The duration of the QRS complex _____A_____ if the plasma [K+] increases from 4mM to 8mM.

 

7.      The duration of the PR interval of the ECG _____C_____ when the conduction velocity of the AV node increases.

 

8.      Ventricular wall tension _____A_____ in response to ventricular dilation (assume no hypertrophy).

 

9.      Ejection fraction _____C_____ after an increase in afterload.

 

10.  As blood flows back to the heart though systemic veins, the velocity _____A_____.

 

11.  Massaging the neck in the region superficial to the carotid sinus (i.e., a carotid massage) _____C_____ heart rate.

 

12.  Vascular tone _____C_____ following activation of KATP channels on vascular smooth muscle cells.

 

13.  For an arteriole that demonstrates pressure autoregulation, nitric oxide (NO) synthesis _____B_____ following a drop in blood pressure within this vessel.

 

14.  Coronary blood flow _____A_____ during the initial phase of diastole.

 

15.  When a normal healthy person suddenly stands up from a supine position, stroke volume _____C_____.

 

16.  Plasma oncotic pressure _____C_____ during the progression of chronic renal failure. 

 

17.  The total cross-sectional area of the respiratory tract _____A_____ in the respiratory zone because of the number of small airways.

 

18.  At low lung volumes, expiratory flow (as measured on an expiratory flow-volume curve) _____B_____ with increasing expiratory effort.

 

19.  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 _____A_____.

 

20.  The percentage of oxygen in the atmosphere _____B_____ when barometric pressure is decreased by 50%.

 

21.  Increasing lung volume above FRC _____A_____ pulmonary vascular resistance.

 

22.  Blood loss (hemorrhage) secondary to trauma _____A_____ the amount of lung under zone 1 conditions.

 

23.  The Haldane effect demonstrates that increased O2 saturation (i.e., high PO2) shifts the CO2 dissociation curve to the right which _____C_____ the CO2 content of the blood.

 

24.  The ventilatory response to a constant hypoxic stimulus _____A_____ when CO2 levels are elevated.

 

25.  Treatment with an angiotensin II receptor blocker will _____C_____ adrenal aldosterone secretion.

 

26.  Infusion of HCO3- will _____C_____ renal excretion of titratable acid.

 

27.  Doubling dietary sodium intake will _____A_____ the volume of the extracellular fluid compartment.

 

28.  A fall in plasma pH will tend to _____A_____ plasma potassium concentration.

 

29.  Therapeutic use of furosemide, will tend to _____A_____ potassium excretion in this segment.

 

30.  Decreased flow, to a subnormal rate, through the ascending limb will _____A_____ the blood flow to the same nephron.

 

31.  An increase in urinary solute excretion will _____A_____ the excretion of water.

 

32.  Relaxation of podocyte foot processes will _____A_____ the value of the ultrafiltration coefficient (Kf).

 

33.  The O2 carrying capacity of blood _____C_____ in chronic renal failure.

 

34.  In a patient with left ventricular systolic dysfunction (congestive heart failure), lung compliance _____C_____ compared to normal.

 

Section 3:  For each of the following, choose the single best response.

 

 

35.  A patient’s ECG shows an inverted T wave.  It is possible that this patient exhibits:

a.       an increased duration of the epicardial plateau phase.

b.      a decreased duration of the endocardial plateau phase.

c.       a significantly decreased conduction velocity within the Purkinje system.

d.      All of the above are possible causes.

 

36.  Which of the following would generate a left shift in the ventricular function curve (cardiac function curve)?

a.       a substantial decrease in preload

b.      an increase in the initial myocardial fiber length

c.       increased parasympathetic stimulation to the heart

d.      administration of cardiac glycosides

 

37.  In response to an increase in central venous pressure:

a.       cardiac output remains unchanged.

b.      stroke volume increases.

c.       the vascular function curve will shift to the right.

d.      none of the above will occur.

 

38.  An increase in cAMP levels in cardiac myocytes occurs through which of the following mechanisms?

a.       activation of a receptors coupled to G proteins which increase IP3 levels

b.      release of calcium from the sarcoplasmic reticulum

c.       activation of b receptors coupled to G proteins that activate adenylate cyclase.

d.      Ach binding to muscarinic receptors

e.       none of the above

 

39.  In regards to the Baroreceptor and Bainbridge reflexes:

a.       When blood pressure at the carotid sinus rises, there is an increase in sympathetic activity.

b.      An increase in right atrial pressure, will lead to a decreased cardiac output.

c.       Stimulation of atrial receptors will activate the Bainbridge reflex.

d.      Baroreceptors respond directly to atrial stretch.

e.       The Bainbridge reflex decreases sympathetic activity.

 

40.  A patient has a heart rate of 67 beats/min, a pulmonary vein O2 content of 0.21 mL O2 / mL blood, a stroke volume of 77 mL/beat, and a pulmonary artery O2 content of 0.14 mL O2 / mL blood.  What is this patient’s oxygen consumption?

a.       540 mL O2 / min

b.      1083 mL O2 / min

c.       470 mL O2 / min

d.      361 mL O2 / min

e.       722 mL O2 / min

 

41.  During exercise, stroke volume increases before preload increases.  The explanation for this is:

a.       an increase in angiotensin II.

b.      a decrease in heart rate.

c.       an increase in total peripheral resistance (TPR).

d.      an increase in intracellular Ca2+ (Staircase Phenomenon).

 

Use the following diagram to answer questions 42-43

 

42.  The labeled point B is chronologically closest to:

a.       the second heart sound.

b.      isovolumetric relaxation.

c.       the P wave of the ECG.

d.      the v wave of the venous pulse.

 

43.  The labeled point C corresponds to:

a.       end diastolic volume.

b.      closing of the mitral valve.

c.       systolic pressure.

d.      the QRS complex.

 

 

44.  The above figure would correspond to which of the following problems?

a.       Aortic insufficiency

b.      Mitral regurgitation

c.       Aortic stenosis

d.      Hypervolemia

 

45.  Regarding the left and right heart which of the following is true?

a.       Left heart rate is faster than right heart rate.

b.      Arteries on both sides supply oxygenated blood to tissues.

c.       Total peripheral resistance and vascular resistance are equal.

d.      Cardiac output can be measured on either side and will be equivalent.

e.       Systemic and pulmonary pressures are equal.

 

46.  Mild cardiac failure results in a(n) ________ of the cardiac function curve.  The compensation for this is systemic fluid retention that is seen as a ________ of the vascular function curve.

a.       downward shift; right shift

b.      downward shift; left shift

c.       upward shift; right shift

d.      upward shift; left shift

e.       Mild cardiac failure results in no shift of the curve and therefore has no compensation.

 

47.  A paid experimental subject was injected with 1.0 gram of inulin and 10 mg of Evan’s blue.  Following a suitable equilibration period, a blood sample was obtained that had an inulin concentration of 50 mg/L and an Evan’s blue concentration of 2.3 mg/L. The hematocrit was 0.4.  During the equilibration period, the individual voided 300 mL of urine that contained 0.5 mg/mL of inulin and no Evan’s blue.  On the basis of this information, the subject’s plasma volume:

a.       is approximately 10.0 mL.

b.      is approximately 4.4 L.

c.       is approximately 7.3 L.

d.      is approximately 17.0 L.

e.       cannot be determined.

 

48.  With reference to the previous question, which of the following best describes the distribution of inulin within this individual following equilibration?

a.       It is distributed throughout both intracellular and extracellular fluids.

b.      It is distributed only within blood cells and plasma.

c.       It is distributed only within plasma.

d.      It is distributed only within interstitial fluids

e.       It is distributed only within plasma and interstitial fluids.

 

49.  For a patient with a systemic blood pressure of 130/85 mmHg and a total peripheral resistance (TPR) of 15 mmHg · min/L, what is cardiac output? 

a.       5.67 L/min

b.      6.67 L/min

c.       7.17 L/min

d.      8.67 L/min

e.       Cardiac output cannot be determined from this information.

 

50.  All of the following will increase arterial pulse pressure EXCEPT an increase in:

a.       stroke volume.

b.      heart rate.

c.       total peripheral resistance.

d.      compliance.

e.       venous return.

 

51.  Stimulation of b2 receptors on vascular smooth muscle cells will result in:

a.       an increase in IP3.

b.      membrane depolarization.

c.       activation of myosin light chain kinase (MLCK).

d.      activation of protein kinase C.

e.       reduction in intracellular Ca2+.

 

 

52.  The figure above shows the labeled phases of a Valsalva maneuver from a normal patient.  Heart rate demonstrates the most marked increase (i.e., the largest degree of change) during which phase of the maneuver?

a.       Phase 1

b.      Phase 2

c.       Phase 3

d.      Phase 4

e.       Heart rate remains constant throughout the entire Valsalva maneuver.

 

53.  Which of the following compensatory responses to hemorrhage occurs within the shortest time frame?

a.       An increase in aldosterone secretion.

b.      An increase in angiotensin II.

c.       Interstitial fluid shifts into plasma.

d.      Baroreceptor-mediated activation of the sympathetic system.

e.       All of the above occur within the same time frame.

 

54.  Which of the following solutes would have the highest capillary permeability across continuous capillaries in the heart?

a.       CO2

b.      Urea

c.       Glucose

d.      Sucrose

e.       Albumin

 

55.  Following the infusion of a physiological dose of epinephrine into an otherwise healthy patient will result in:

a.       a decrease in heart rate.

b.      a decrease in total peripheral resistance.

c.       an increase in aortic diastolic pressure.

d.      a decrease in cardiac output.

e.       all of the above.

 

56.  The conducting airways

a.       transport O2 and CO2 between the gas exchange regions of the lung and the metabolically active tissues.

b.      are the primary site of gas exchange.

c.       include the respiratory bronchioles.

d.      comprise of the anatomical dead space in a healthy individual.

e.       a and c

 

57.  Transpulmonary pressure is equal to

a.       Alveolar pressure minus intrapleural pressure.

b.      Alveolar pressure minus atmospheric pressure.

c.       Atmospheric pressure minus alveolar pressure.

d.      Intrapleural pressure minus atmospheric pressure.

e.       Intrapleural pressure minus alveolar pressure.

 

58.  At functional residual capacity (end expiration),

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.       the inward directed elastic recoil of the lung is less than that of the outward directed elastic recoil of the chest wall.

d.      the elastic recoil of both the lung and chest wall are directed inward.

e.       the elastic recoil of both the lung and chest wall are directed outward.

 

59.  Lung compliance

a.       Represents the relationship between changes in the pressure distending the alveoli and the corresponding changes in lung volume.

b.      Increases in restrictive pulmonary disease (i.e., pulmonary fibrosis).

c.       Decreases in obstructive pulmonary disease (i.e., emphysema).

d.      Is greatest at high lung volumes.

e.       All of the above.

 

60.  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.

 

61.  Airways resistance

a.       Can only be measured when air is flowing into or out of the lungs.

b.      Is extremely high at low lung volumes due to dynamic compression of the airways.

c.       Increases during stimulation of the parasympathetic postganglionic fibers innervating the bronchial smooth muscle.

d.      Is higher in the small airways than in the medium sized bronchi because the small airways are arranged in parallel.

e.       a, b, and c.

 

62.  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

e.       FEV1

 

63.  Which of the following factors may reduce the FEV1 in a patient with chronic obstructive pulmonary disease (COPD)?

a.       reduction in the number of small airways

b.      excessive secretions in the airways

c.       loss in radial traction on the airways

d.      loss of elastic recoil in the lung

e.       all of the above factors may contribute to reduced FEV1

 

64.  The inspiratory flow-volume curve is particularly valuable for

a.       differentiating between chronic bronchitis and emphysema.

b.      measuring dynamic compression of the airways.

c.       measuring the response to bronchodilator drugs.

d.      measuring the resistance of the very small airways.

e.       detecting fixed upper airway obstruction.

 

65.  Which patient has the highest minute ventilation?

a.       Tidal volume = 1000 ml; Frequency = 9 breaths/min; Dead space volume = 150 ml

b.      Tidal volume = 600 ml; Frequency = 15 breaths/min; Dead space volume = 150 ml

c.       Tidal volume = 500 ml; Frequency = 18 breaths/min; Dead space volume = 150 ml

d.      Minute ventilation is the same in all cases.

 

66.  Which of the following is not true regarding the pulmonary circulation as compared to the systemic circulation

a.       the pulmonary circulation has the same blood flow per minute.

b.      pulmonary arterial vessels have the same vascular smooth muscle response to hypoxia.

c.       pulmonary arterial vessels have thinner walls and greater internal diameters than corresponding branches of the systemic vessels.

d.      pulmonary arterial vessels have lower intravascular pressures than those found in systemic arteries.

e.       a and b.

 

67.  Which of the following is not true regarding diffusion of O2 and CO2 in the lungs?

a.       Diffusion of both O2 and CO2 are unaffected by marked thickening of the blood-gas barrier.

b.      The partial pressure gradient for diffusion of O2 is greater than the partial pressure gradient for diffusion of CO2.

c.       Under normal conditions, diffusion of both O2 and CO2 follow a similar time course.

d.      The surface area available for diffusion is increased during exercise due to increased blood flow.

e.       a and c.

 

68.  A patient with severe carbon monoxide (CO) poisoning was given a transfusion of stored blood.  Measurement of his hemoglobin-oxygen dissociation curve showed a marked reduction in the P50.  The most likely causative factor was

a.       arterial CO2 retention.

b.      reduced arterial pH.

c.       abnormally low concentration of 2,3-DPG in the transfused red blood cells.

d.      increased blood temperature.

 

69.  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.

 

70.  What mechanism of is responsible for most, if not all, of the arterial hypoxemia associated with pulmonary disease (e.g., COPD; interstitial lung disease)?

a.       Hypoventilation

b.      Diffusion impairment

c.       Shunt

d.      Ventilation-perfusion inequality

 

71.  The apex, compared with the base, of the upright lung

a.       has a low PO2.

b.      has a high PCO2.

c.       has a high ventilation-perfusion ratio.

d.      has smaller alveoli.

e.       has higher compliance.

 

72.  Voluntary apnea (breath-holding) 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.

 

73.  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 intercostal muscles

d.      Loss of tone of the genioglossus muscle

e.       Snoring

 

74.  Which of the following is NOT a characteristic of the renal circulation?

a.       The endothelial cells of the preglomerular arterial vessels produce prostaglandins in response to angiotensin II.

b.      The hydostatic pressure along the glomerular capillaries is essentially constant.

c.       Blood flow to the medulla is provided by the efferent arterioles of juxtamedullary nephrons.

d.      The innervation of the intrarenal arterial system mainly consists of equal mix of parasympathetic and sympathetic nerves.

 

75.  Which of the following statements about the glomerulus is FALSE? 

a.       The relative filterability of a cationic macromolecule (30 kD MW) will generally exceed that of an uncharged macromolecule of equivalent size.

b.      At the beginning of the glomerular capillaries, net filtration pressure is about 20 mmHg. 

c.       The endothelial lining of the glomerular capillaries is unfenestrated in order to restrict the filtration of plasma proteins.

d.      The mesangial cell network in the glomerulus provides structural support for the capillaries. 

 

76.  Which of the following is FALSE?

a.       A rise in plasma glucose concentration will tend to increase sodium entry through the apical membrane of proximal tubular cells.

b.      Net proximal tubular reabsorption is dependent on the net reabsorptive pressure present in the peritubular capillaries.

c.       In the proximal tubule, the secretion of H+ via Na/H exchange does not influence chloride reabsorption, whether directly or indirectly.

d.      In the second half of the proximal tubule, significant paracellular passive sodium and chloride reabsorption occurs. 

 

77.  Which of the following is FALSE?  

a.       In the initial portion of the distal convoluted tubule, there is little water reabsorption.

b.      In the principal cells of the cortical collecting ducts, apical transport of sodium is mediated by a sodium-chloride cotransporter that is inhibited by the thiazide.

c.       The density of aquaporin molecules in the apical membrane of principal cells is regulated by ADH through a process involving cAMP. 

d.      The fluid in the thin ascending limb segments is more dilute than the fluid in the surrounding interstitium.


 

78.  A person is infused with PAH.  After equilibration, urinary PAH excretion is 100 mg/min, PPAH is 0.20 mg/mL. What is renal plasma flow?

a.       120 mL/min

b.      500 mL/min

c.       600 mL/min

d.      None of the above are within 10 mL/min of RPF.

 

79.  Consider the figure above. Which of the following statements best describes the transport of the freely-filtered substance?

a.       The substance is reabsorbed by a carrier-mediated process.

b.      The plasma threshold concentration of the substance is 1 ug/ml.

c.       The Tm is 100 ug/min.

d.      The substance does not exhibit a Tm.                           

 

80.  A company measures the renal handling of a new pain killer.  The drug is freely filtered and not metabolized in the body.  Renal studies show that the clearance of the drug is 50 mL/min, while inulin clearance is 120 mL/min.  How is the drug handled by the kidney tubules?

a.       The drug is not reabsorbed or secreted by the renal tubules.

b.      The drug is subjected to net secretion by the renal tubules.

c.       The drug  is subjected to net reabsorption by the renal tubules.

d.      There is no net transport of the drug by the tubules.

 

81.  Which of the following statements is FALSE?

a.       Dietary sodium intake will have a substantial effect of blood pressure in a person with hyperaldosteronism (persistent, high plasma aldosterone levels).

b.      In renal-vascular hypertension, systemic BP rises until the intravascular pressures within the renal microcirculation are normalized.

c.       The addition of one liter of distilled water to the extracellular fluid will not change intracellular fluid volume.

d.      During a period of negative sodium balance, there will be a net loss of water from the body.

 

82.  Which of the following statements is FALSE?

a.       The urea content of the inner medulla is higher in an anti-diuresis than in a water diuresis.

b.      Furosemide therapy will tend to limit the ability of the kidney to produce maximally dilute urine.

c.        The counter-flow in the vasa recta is important because it traps oxygen in the inner medulla.

d.      Under normal conditions, approximately half of the Na+ ions reabsorbed by thick ascending limb cells move through the tight junctions.

 

83.  Which of the following statements is FALSE? 

a.       Angiotensin converting enzyme is located only in pulmonary blood vessels.

b.      Renin secretion is inhibited by increased flow through Henle’s loop and distension of cardiac atria.

c.       Angiotensin II stimulates prostaglandin release by the endothelial cells of the afferent arteriole.

d.      The number of renin-containing granular cells will increase in response to prolonged low dietary salt intake.

 

84.  Which of the following statements about the distal tubule and collecting ducts is FALSE?

a.       The intercalated cells transport hydrogen ions only by Na/H exchange.

b.      The rates of sodium reabsorption and potassium secretion usually change in parallel, but this linkage can be altered by ANP in the inner medullary collecting ducts.

c.       K+ secretion into the lumen of the distal tubule is passive and will tend to increase when tubular fluid [K+] is low.

d.      ADH enhances K+ secretion in these segments by increasing the electrochemical gradient that drives K+ into the lumen.


 

85.  Regarding renal acid-base handling, which of the following statements is FALSE?

a.       In a respiratory acidosis, plasma [HCO ] will rise above normal as a consequence increased renal H+ secretion. 

b.      In a metabolic alkalosis, the pH of renal venous blood will be higher than the blood entering kidney.

c.       The reabsorption of bicarbonate in the proximal tubule involves titration of bicarbonate in the tubular lumen and the release of newly synthesized bicarbonate into the renal interstitium.

d.      Buffering of protons by proteins is relatively more important in a respiratory acidosis than in a metabolic acidosis.

 

86.  A person has a plasma [HCO ] of 34 meq/l and PCO2 of 45 mmHg.  Which of the following values is closest to the plasma pH of the person?

a.       7.2

b.      7.4

c.       7.5

d.      7.8

 

87.  A person has an arterial pH of 7.3 and PCO2 of 34 mmHg.  Which of the following is most consistent with these values?

a.       Metabolic acidosis

b.      Metabolic alkalosis

c.       Respiratory acidosis

d.      Respiratory alkalosis

 

88.  Urine flow is 2 liters/day and the urine contains 10 mM HCO, 1 mM NH, and 0 mM titratable acid.  What is the rate of urinary acid excretion?                                       

a.       11 mmoles/day

b.      22 mM/day

c.       18 mmoles/day

d.      None of the above

 

89.  Lab tests from a patient with chronic renal failure reveal that their plasma creatinine concentration is 8 mg/dL compared to a normal value of 1 mg/dL.  Assuming a normal GFR of 100 mL/min, this patient’s GFR:

a.       is approximately 100 mL/min.

b.      is approximately 12.5 mL/min.

c.       is approximately 8 mL/min.

d.      is approximately 0.125 mL/min.

e.       cannot be determined from the available information.

 

 

90.  The above figure shows the pressure-volume relationship for a normal heart (abcd) and a heart in uncompensated congestive heart failure (a’b’c’d’).  On the basis of these data, you can conclude that compared to the normal heart, in the failing heart,

a.       there is evidence of aortic insufficiency.

b.      stroke volume is increased.

c.       the ejection fraction is unchanged.

d.      the amount of blood left in the ventricle following systole is increased.

e.       the residual volume is decreased.