Cardiac output variables

Question 1

Stroke volume affected by

Answer 1

Stroke Volume affected by Contractility, Afterload, and Preload.

“SV CAP”

Question 2

SV increases when

Answer 2

Preload increases,
Afterload decreases,
Contractility increases

Question 3

Contractility and SV increase with

Answer 3

1) catecholamine (increased Ca2+ pump activity of SR)
2) high intracellular Ca2+
3) low extracellular Na (decreased activity of Na+/Ca+ exchanger)
4) digitalis (blocks Na/K pump, high intracellular Na, low Na/Ca exchanger activity, high intracellular Ca)

Question 4

Contractility and SV decrease with

Answer 4

1) beta 1 blockage (low cAMP)
2) heart failure (systolic dysfunction)
3) acidosis
4) hypoxia/hypercapnea (low PO2/high PCO2)
5) non dihydropyridine Ca2+ channel blocker

Question 5

Physiologic responses that increase SV

Answer 5

Anxiety, exercise, and pregnancy

Question 6

Myocardial O2 demand increases by

Answer 6

1) increased afterload (proportional to arterial pressure)
2) increased contractility
3) increased HR
4) increased heart size (increased wall tension)