Exercise And The Heart

Question 1

What are the cardiovascular changes which occur with exercise?

Answer 1

Increased blood flow to skeletal muscle
Increased cardiac ouput
Decreased blood flow to non essential organs
Vasodilation in the skin

Question 2

How is the increased blood flow to skeletal muscle during exercise mediated?

Answer 2

By local factors such as histamine and kinins which induce vasodilation and by the action of adrenaline of beta two receptors

Question 3

How is the increased cardiac output with exercise mediated?

Answer 3

Increased sympathetic activity which acts through beta one receptor on the heart to increase heart rate and increase ventricular contractility to increase stroke volume. decreased parasympathetic activity at the nodes and ventricles. This increases heart rate and stroke volume to increase cardiac output

Question 4

How is the decreased blood flow to non essential organs with exercise mediated?

Answer 4

There is increased sympathetic activity acting through alpha one receptors to increase vasoconstriction in these areas

Question 5

How is vasodilation in the skin to promote heat loss during exercise mediated?

Answer 5

Decrease in sympathetic activity acting on alpha one receptors

Question 6

Mean arterial pressure increases during exercise. Why does this happen?

Answer 6

The vasodilation of the skeletal muscles, heart and skin overrides vasoconstriction of the kidneys and GI organs to decrease TPR
Cardiac output has increased to a much greater extent than TPR has decreased however so MAP increases

Question 7

What are the factors which promote venous return during exercise?

Answer 7

Increased activity of skeletal muscles to act as a pump
Increased depth and frequency of inspiration
Sympatheticqlly mediated increase in venous tone
Greater ease of blood flow from arteries to veins through dilated skeletal muscle arterioles