HBY 531 MEDICAL PHYSIOLOGY

Lecture Exam 2

2003

Section 1: Answer the following using:

a = becomes more positive

b = remains the same

c = becomes more negative

1. The maximum diastolic potential of a Purkinje fiber_______ if the external [K] is raised from 4mM to 10mM in the bathing solution

2. The maximum diastolic potential of a sinus node myocyte_____ after a beta agonist is added to the bathing solution

Section 2: Answer the following using:

a = increases

b = remains unchanged, causes no change in

c = decreases

3. The interval between sinus node action potentials_____ if acetylcholine is added to the bathing solution

4. The duration of the P wave of the EKG______ if the conduction velocity of the Purkinje fibers is slowed.

5. The duration of the QRS complex______ if the plasma [K] is reduced from 4mM to 0.5mM

6. The amplitude of contraction of a ventricular myocyte______ if a beta agonist is added to the bathing solution.

7. The duration of a sinus node action potential_______ when the vagus nerve is being stimulated.

8. As the end-diastolic volume is increased from 100 mL to 130 mL, stroke volume_______

9. The velocity of contraction within the ventricle ________ during isovolumetric contraction.

10. As the mean arterial pressure is increased from 95 to 115 mmHg, end-systolic volume within the left ventricle ________.

11. Following selective stimulation of the sympathetic nerves to the heart, central venous pressure ___________.

12. The pressure within the portal vein _______ following an infusion of propranolol (a non-specific b blocker).

13. As a vein vasoconstricts (venoconstriction), the compliance of the vessel wall _______.

14. Local vascular resistance ________ following an increase in adenosine levels in the interstitial fluids surrounding vascular smooth muscle cells.

15. Local vascular resistance ________ following infusion of phenylephrine (an a1 agonist).

16. As a normal healthy person moves upright from a supine position, stroke volume _________.

17. The hydrostatic pressure within a systemic capillary _________ following a decrease in arteriolar vascular resistance.

18. The airways consist of a series of branching tubes which become progressively narrower and shorter as they penetrate deeper into the lung. This results in a(n)_____ in total cross sectional area of the respiratory tract.

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

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

21. The Bohr effect demonstrates that increased CO₂ (i.e., high PCO₂) shifts the O₂ dissociation curve to the right which ___ the O₂ content of the blood.

22. The Haldane effect demonstrates that decreased O₂ saturation (i.e., high PO₂) shifts the CO₂ dissociation curve to the left which ___ the CO₂ content of the blood.

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

The figure shown above is a pressure-volume loop from a normal, healthy adult. Use this figure to answer questions 23 and 24.

23. The mitral valve closes:

a. at point a

b. at point b

c. at point c

d. at point d

e. somewhere between points b and c

24. Which portion of the pressure volume loop correlates with the T wave of the EKG?

a.