Acute Responses

Acute Cardiovascular System Responses

During exercise, the cardiovascular system needs to deliver greater amounts of oxygen and energy substrates to the working muscles. This is done to meet the increasing demands of the activity. The focus is on getting more blood to the working muscles to meet this need and to speed up the removal of carbon dioxide and other wastes. In order to do this the cardiovascular system undergoes a number of changes, including:

Cardiac Output

The amount of blood pumped out of the left ventricle per minute. It is made up of stroke volume x heart rate.
3D Heart animation - how the heart pumps blood

Blood Pressure

The amount of pressure exerted on the arteries when the ventricles contract (systolic) and relax (diastolic).

Differences in blood pressure occurs because more blood is being pumped out per beat/minute and therefore it causes an increase in pressure.

Venous Return

The amount of blood that is returned back to the heart via the veins.

This occurs so than an increase in cardiac output can take place. When there is more blood being delivered to the heart, more can be pumped back out into the body to deliver oxygen to the muscles, and carbon dioxide to the lungs.

Redistribution of Blood Flow

During exercise, blood flow is redirected away from the spleen, kidneys, gastrointestinal tract and inactive, and is directed to the working muscles. This is so the muscles can receive the greater percentage of oxygen and cardiac output.

Oxygen Consumption / Arteriovenous Oxygen Difference

The volume of oxygen that can be taken up and used by the body. The difference in oxygen concentration in the arterioles compared to the venules.

This response occurs to increase the amount of oxygen that is delivered and used by the working muscles.