Lecture 12 - Flow Control and Cardiac Output Flashcards
Cardiac output per square meter of BSA A. Cardiac filling pressure B. Cardiac throughput C. Cardiac index
C. Cardiac index
Which of the following factors does not directly influence cardiac output? A. Basal metabolic rate B. Exercise C. Body fat D. Body size
C. Body fat
Flick principle of blood flow:
CO = Oxygen consumed/(PvO2-PaO2)
The primary determinant of cardiac output is:
venous return to the heart
Blood pressures are higher in the (pulmonic/systemic) circuit.
systemic
Stretching of right atria produces an increase in heart rate
Bainbridge reflex (doesn’t normally occur in adult humans)
The Bainbridge reflex only occurs in this set of the adult population.
pregnant females, post delivery with the return of uteroplacental blood to maternal circulation
Explain the mechanism of HTN in relation to the creation of a “hypoeffective heart.”
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.
Explain the mechanism behind inhibition of the nervous system in creating a hypoeffective heart.
Decreased SNS tone will produce greater vasodilation, which increases venous capacitance, thereby decreasing venous return.
Explain how valvular heart disease may contribute to a hypoeffective heart.
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.
Increased right atrial pressure will cause a(n) (decrease/increase) in cardiac output.
decrease
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
A. increase; decrease; increase
AV fistulas produces a(n) ____ in TPR, and a(n) ____ in CO. A. decrease; increase B. decrease; increase C. decrease; decrease D. increase; increase
B. Decrease; increase
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
D. increase; decrease; decrease
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
B. decrease; decrease; increase
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
A. increase; decrease; decrease
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
D. increase; decrease; increase
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
A. increased right atrial pressure
This is the pressure when heart pumping ceases
mean circulatory filling pressure (pressures throughout system are in equilibrium)
Formula for venous return
VR = (Psf-RAP)/Resistance to venous return
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
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.
T/F: Coronary blood flow increases during systole
False (systole compresses the coronary arteries)
T/F: Coronary arteries fill during diastole
True
What is the primary controller of coronary blood flow? A. Direct ANS stimulation B. Indirect ANS stimulation C. Local metabolism D. Presence of vasoldilators
C. Local metabolism; coronary flow increases in direct proportion to metabolic activity (possibly due to adenosine released by ATP breakdown)
Describe the mechanism of pulmonary edema in coronary occlusion?
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.
Describe the mechanism behind “systolic stretch” in cardiac ischemia and its effect on cardiac output.
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.
Blood pumped into the aorta every minute. A. Cardiac throughput B. Cardiac output C. Cardiac index D. Cardiac filling pressure
B. Cardiac output
A?
B?
C?
D?
E?
F?
A. Aorta
B. Pulmonary A.
C. Left coronary A.
D. Left circumflex A.
E. Right coronary A.
F. Left anterior descending a.
