Question

Explain the cardiac and vascular changes that take place during exercise. Ensure you include a description of stroke volume, heart rate, blood flow to tissues and blood pressure

Answer 1

exercise causes

Increases in stroke volume

Heart rate raise cardiac output

Increase in systemic vascular resistance.

Elevate mean arterial blood pressure.

Heart rate changes:

The heart rate increases when we start exercise upto some extent. Within 4 to 5 minutes of exercise the maximal rise is achieved due to influence of the cerebral cortex on the medullary cardiac centre.. After some time the rate is decreased .

Cardiac Output:

During the exercise the cardiac output is greatly increased. the output may be average 22 litres at an O₂ uptake of 3.3 litres per minute. This is due to the increase of  stroke volume.

Venous Return:

During the exercise, the alternate contraction and relaxation of the muscle act as a booster pump for flowing blood to the heart.

Due to the presence of valves in the veins, the blood is pumped out from the vein towards the heart during contraction and fill blood during relaxation of muscle.

Blood Pressure:

Blood pressure is raised with the exercise. There blood pressure is due to nerve impulses originating from the cerebral cortex to the medullary cardiac and vasocon­strictor centres.

Other reasons that may participate in the rise of blood pressure during exercise are due to activation of sympathetic adrenal systems.

So rise in blood pressure increases due to Increase of heart rate, Increase of cardiac output

Blood flow to tiisues:

During the exercise, the blood flow in the active muscles, lung, heart is increased, but the abdominal organ, kidneys and in the skin; initially is decreased due to the compensatory vasoconstriction.

During the exercise, the circulation is adjusted in such a way that the active muscles and the vital organs get blood supply to a greater than the inactive organs and the non-vital organs.