Lecture 12 - Flow Control and Cardiac Output

Question 1

Cardiac output per square meter of BSA A. Cardiac filling pressure B. Cardiac throughput C. Cardiac index

Answer 1

C. Cardiac index

Question 2

Which of the following factors does not directly influence cardiac output? A. Basal metabolic rate B. Exercise C. Body fat D. Body size

Answer 2

C. Body fat

Question 3

Flick principle of blood flow:

Answer 3

CO = Oxygen consumed/(PvO2-PaO2)

Question 4

The primary determinant of cardiac output is:

Answer 4

venous return to the heart

Question 5

Blood pressures are higher in the (pulmonic/systemic) circuit.

Answer 5

systemic

Question 6

Stretching of right atria produces an increase in heart rate

Answer 6

Bainbridge reflex (doesn’t normally occur in adult humans)

Question 7

The Bainbridge reflex only occurs in this set of the adult population.

Answer 7

pregnant females, post delivery with the return of uteroplacental blood to maternal circulation

Question 8

Explain the mechanism of HTN in relation to the creation of a “hypoeffective heart.”

Answer 8

Increased hypertension is essentially an increase in “after-load.” The increased arterial pressure results in a greater force that the left ventricle must push against to maintain normal cardiac output.

Question 9

Explain the mechanism behind inhibition of the nervous system in creating a hypoeffective heart.

Answer 9

Decreased SNS tone will produce greater vasodilation, which increases venous capacitance, thereby decreasing venous return.

Question 10

Explain how valvular heart disease may contribute to a hypoeffective heart.

Answer 10

If the valves are unable to seal properly, there will be no isovolumic contraction/relaxation. That will change the amount of blood either received or expelled by the heart, which changes cardiac output.

Question 11

Increased right atrial pressure will cause a(n) (decrease/increase) in cardiac output.

Answer 11

decrease

Question 12

Beriberi produces a(n) ____ in vasodilation, a(n) ____ in TPR, and a(n) ____ in CO. a. increase; decrease; increase b. decrease; increase; decrease c. increase; increase; decrease d. decrease; increase; increase

Answer 12

A. increase; decrease; increase

Question 13

AV fistulas produces a(n) ____ in TPR, and a(n) ____ in CO. A. decrease; increase B. decrease; increase C. decrease; decrease D. increase; increase

Answer 13

B. Decrease; increase

Question 14

Hyperthyroidism produces a(n) ____ in vasodilation, a(n) ____ in TPR, and a(n) ____ in CO. A. increase; decrease; decrease B. decrease; increase; increase C. decrease; decrease; decrease D. increase; decrease; decrease

Answer 14

D. increase; decrease; decrease

Question 15

Anemia produces a(n) ____ in vasodilation, a(n) ____ in TPR, and a(n) ____ in CO. A. increase; decrease; increase B. decrease; decrease; increase C. increase; increase; decrease D. decrease; increase; decrease

Answer 15

B. decrease; decrease; increase

Question 16

Decreased skeletal muscle mass produces a(n) ____ in vasodilation, a(n) ____ in TPR, and a(n) ____ in CO. A. increase; decrease; decrease B. decrease; decrease; decrease C. increase; increase; increase D. decrease; increase; decrease

Answer 16

A. increase; decrease; decrease

Question 17

Paget’s disease produces a(n) ____ in vasodilation, a(n) ____ in TPR, and a(n) ____ in CO. A. increase; increase; increase B. increase; increase; decrease C. decrease; decrease; decrease D. increase; decrease; increase

Answer 17

D. increase; decrease; increase

Question 18

This is a large limiter of venous return to the right heart A. increased right atrial pressure B. decreased right atrial pressure C. increased TPR D. decreased TPR

Answer 18

A. increased right atrial pressure

Question 19

This is the pressure when heart pumping ceases

Answer 19

mean circulatory filling pressure (pressures throughout system are in equilibrium)

Question 20

Formula for venous return

Answer 20

VR = (Psf-RAP)/Resistance to venous return

Question 21

A patient suffers cardiac arrest, during which they receive 2 L of chilled IV fluids. What effect, from a mean systemic pressure standpoint, will this have on venous return? A. No change to venous return B. Increase in venous return C. Decrease in venous return D. Unable to determine

Answer 21

B. Increase in venous return Increased circulating blood volume (as evidenced by the chilled fluid coupled with CPR) will increase the venous return. In other words, the fluid bolus would (if resuscitation were halted) increase the Psf. This is directly proportional to increased venous return.

Question 22

T/F: Coronary blood flow increases during systole

Answer 22

False (systole compresses the coronary arteries)

Question 23

T/F: Coronary arteries fill during diastole

Answer 23

True

Question 24

What is the primary controller of coronary blood flow? A. Direct ANS stimulation B. Indirect ANS stimulation C. Local metabolism D. Presence of vasoldilators

Answer 24

C. Local metabolism; coronary flow increases in direct proportion to metabolic activity (possibly due to adenosine released by ATP breakdown)

Question 25

Describe the mechanism of pulmonary edema in coronary occlusion?

Answer 25

Coronary occlusion produces a decrease in cardiac output by producing a hypoeffective heart. As a result, this will produce decreased blood flow to kidneys and decreased urine output secondary to renal “congestion.” This excess circulating fluid volume is often forced into the lungs due to increased capillary hydrostatic pressure.

Question 26

Describe the mechanism behind “systolic stretch” in cardiac ischemia and its effect on cardiac output.

Answer 26

Ischemic tissue has the inability to contract normally during systole. As a result, this region is “inert.” As the chamber in the heart increase with systole, this area is forced outward, thereby increasing the volume of said chamber. This increased volume decreases pressure and decreases cardiac output.

Question 27

Blood pumped into the aorta every minute. A. Cardiac throughput B. Cardiac output C. Cardiac index D. Cardiac filling pressure

Answer 27

B. Cardiac output

Question 28

A?

B?

C?

D?

E?

F?

Answer 28

A. Aorta

B. Pulmonary A.

C. Left coronary A.

D. Left circumflex A.

E. Right coronary A.

F. Left anterior descending a.