HBY 531 MEDICAL PHYSIOLOGY

LECTURE EXAM 2

2004

 

  

Section 1:  Answer the following using:

 

a = becomes more negative

b = remains the same

c = becomes more positive

 

 

1.  The maximum diastolic potential in a ventricular myocyte ______ when external [K+] is decreased from 8 to 3 mM.  (A)

2.  The maximum diastolic potential in a Purkinje fiber _______ when the external [K+] is lowered from 5 to 1 mM.  (C)

3.  The maximum diastolic potential in the sinus node ______ when the vagus nerve is stimulated. (A)

 

Section 2:  Answer the following using:

a = increases

b = remains unchanged

c = decreases

4.  The slope of the diastolic depolarization in the Purkinje fiber ญญ______ when a beta agonist is added to the bathing solution. (A)

5.  The duration of the absolute refractory period in a Purkinje fiber ______ if the plateau duration increases by 50 msec.  (A)

6.  The intracellular [cAMP] in the SA node ______ during vagal stimulation. (C)

7.  The R-R interval of the EKG ______ when the vagus nerve is stimulated. (A)

 

8.  The magnitude of the funny current (if) __________ when the vagus nerve is stimulated.  (C)

9.  The duration of systole ________ following infusion of dobutamine (b1 agonist) into the coronary circulation. (C)

 

10.  Heart rate _______ following infusion of atropine (non-specific muscarinic antagonist) into the coronary circulation. (A)

 

11.  Assuming no change in cardiac output, central venous pressure _________ following the development of hypervolemia in mild cases of congestive heart failure. (A)

 

12.  Assuming no change in cardiac output, central venous pressure _________ following a decrease in arterial vascular resistance. (A)

 

13.  Vascular smooth muscle tone _______ following an increase in Cl- conductance across the membranes of smooth muscle cells. (A)

           

14.  Shear rate __________ as the velocity of blood flow decreases. (C)

           

15.  Vascular resistance _______ in cerebral blood vessels following hyperventilation. (A)

           

16.  Venous return to the right atrium _____ following venoconstriction of splanchnic veins. (A)

           

17.  Total peripheral resistance ________ following an infusion of a therapeutic dose of epinephrine. (C)

           

18.  A young man who was previously well was admitted to the emergency room with barbiturate poisoning that caused severe hypoventilation.  During administration of 100% oxygen to breathe, his arterial PCO2 __________. (B)

 

19.  Within zone 2 of the upright lung, the pressure difference responsible for blood flow _________ with distance toward the base of the lung. (A)

 

20.  When a bronchodilator is administered to a patient with asthma during an attack, the FEV1/FVC _______________. (A)

 

21.  At low lung volumes, expiratory flow (as measured on an expiratory flow-volume curve) __________with increasing expiratory effort. (B)

 

22.  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).  When the tidal volume is increased by 200 mL, PCO2 __________. (C)

 

 

 

 

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

 

 

Questions 23-26:  The following data show two pressure-volume loops obtained from the same experimental subject who is normal and healthy.  The solid curve (loop 1) was obtained at rest, while the dashed curve (loop 2) was also obtained at rest, but following an intravenous infusion of 1 L of saline.

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