The cardiovascular system is composed of the heart, blood vessels and blood. This system is responsible for the transport of nutrients, waste products, gases and hormones throughout the body. In addition, it plays a role in immune responses as well as body temperature regulation. Alterations in the normal behavior of the cardiovascular system can occur with participation in exercise.
Heart Rate
Heart rate refers to the number of heart beats in a unit of time. Most often it is expressed as beats per minute. During exercise, the quantity of blood pumped by the heart must increase to meet the rising demands of oxygen by the muscles. One way to meet this demand is to increase the number of times the heart beats. Thus, heart rate increases are seen with the rising exercise demands.
Stroke Volume
Stroke volume is the amount of blood that is pumped by the ventricles of the heart in a single heart beat. Increasing the amount of blood pumped per heart beat is a way of increasing the amount of blood flow to the skeletal muscles during exercise. Therefore, as exercise increases, so does the stroke volume.
Cardiac Output
Cardiac output is sometimes called minute volume because it is the amount of blood pumped by the heart per minute. It is the product of heart rate and stroke volume. During exercise both heart rate and stroke volume increase which results in an increase in cardiac output.
Blood Pressure
Blood pressure is the tension of the blood within the blood vessels. There are two components of blood pressure. Your systolic blood pressure occurs during the contraction of the ventricles. Your diastolic blood pressure occurs during the relaxation of the heart when the ventricles fill with blood. During exercise, the amount of blood pumped by the ventricles becomes greater which results in an increase in systolic blood pressure. The relaxation phase of the heart changes very little and so changes in diastolic blood pressure are minor.
Redistribution of Blood
During exercise, there is redistribution of blood flow from inactive organs to active skeletal muscles. This allows more oxygen to get to the muscle which is needed during exercise.
References
- "Exercise Physiology;" Scott Powers, Edward Howley; 1997
- "Anatomy and Physiology;" Rod Seeley, Trent Stephens, Philip Tate; 1998
