Stroke Volume

Question 1

Stroke volume is…

Answer 1

The maximum volume of blood pumped from the left ventricle per contraction

Question 2

Determined by several factors:

Answer 2

Venous return
Elasticity of cardiac fibres (diastole)
The contractility of cardiac tissue (myocardium)

Question 3

Venous return is the…

Answer 3

Volume of deoxygenated blood returning to the right atrium

If this increases so does the stroke volume

Question 4

Elasticity - Starlings law:

Answer 4

Amount of stretch of cardiac tissue just before the contraction
Increased venous return
More stretch = greater force of contraction

Question 5

Contractility of cardiac tissue is…

Answer 5

Increased contractility = greater force of contraction

Results from an increased ejection fraction (amount of blood actually pumped out of left ventricle)

Question 6

Stroke volume during exercise increases as exercise intensity…

Answer 6

Increases but only up to 40-60% of max. Effort
Here it plateaus
Shorter diastolic phase due to increased heart rate - simply not enough time for ventricles to fill anymore before heart contracts