Stroke Volume Flashcards
1
Q
Stroke Volume
A
Amount of blood that is pumped in a minute
2
Q
Average SV
A
~70 mL
3
Q
SV depends on
A
Contractility and Venous return
4
Q
Venous return affected by:
A
- skeletal muscle pump
- respiratory pump
- sympathetic innervation
5
Q
Contractility affected by:
A
- stroke volume
- contractility of heart
- length of muscle fibre
6
Q
Frank-Starling Law of the Heart
A
SV increases in response to an increase of blood in heart (when all other factors remain constant)
7
Q
Preload
A
- filling of heart
- more filling = greater stretch of myocardium = greater force of contraction
8
Q
Inotropic effect
A
Norepinephrine INCREASES contractility of heart
SV goes up
9
Q
Cardiac output
A
amount of blood pumped out / min
CO = SV X Heart Rate
~5L
10
Q
Advantages of Exercise
A
- bigger heart = higher stroke volume
- INC coronary artery diameter (better blood flow)
- less chance of ischemia
11
Q
Heart Failure
A
- valve stenosis
- ischemia or infarct
- hypertension
- DEC SV
- heart compensates with high heart rate, means : shorter filling times, faster fatigue, lower contraction, lower SV
12
Q
heart failure
A
muscle so fatigues it doesnt contract
low SV
high Blood volume
excess blood backs into lungs
13
Q
Cardiac Aneurysm
A
- bulge of ventricular wall
- muscle weakness
- congenital or from infarct
