Question

describe the stroke volume and the factors that affect it during rest and during exercise

Answer 1

Stroke volume:

Stroke volume is total volume of blood that is ejected for per ventricle and for per beat in cardiovascular system which plays a major role in determining the cardiac output. The normal stroke volume for a individual ranges from the 70-80 mL.

The factors that determine the stroke volume is preload- it is a filling pressure created in the heart that happens in the end of diastole, Contractility- A strong active contraction of muscle of heart at the systole, Afterload- It is a pressure that is created against the heart for the purpose of ejection of blood at the systole. Any factors that affect the determinant of stroke volume that are the factors affects the stroke volume at rest.

In preload, the factors like fast filling time, increased venous return increases the stroke volume by increasing the end diastolic volume that happens during exercise.

In preload, the factors like less thyroid hormones, less calcium ions, high potassium ions, low potassium ions, abnormal pH, hypoxia, abnormal sodium ions, reduced body temperature or any drugs like calcium channel blockers will decrease the stroke volume at rest by reducing the end diastolic volume.

In contractility, any sympathetic stimulation, epinephrine or norepinephrine activity, high calcium ions in the intracellular, glycagon production are factors leads to increase in stroke volume almost in exercise.

In contractility, any parasympathetic stimulation, hypoxia, acetylcholine release, high sodium ions are the factors leads to increase the stroke volume at rest.

In afterload, high vessel or vascular resistance , any valve damage are the factors affect stroke leads to increase in stroke volume even at rest. And it is also decreased by the low vascular resistance.