Question

How does the heart change its rate?

Answer 1

Heart rate is the number of heart beats per minute. The heart rate is based on the number of contractions of the ventricles (the lower chambers of the heart). The heart rate may be too fast (tachycardia) or too slow (bradycardia).

Complete answer:
The cardiovascular framework circles blood all through the body to supply oxygen and different supplements and to eliminate by-products. Each time the heart beats; blood is siphoned out of the heart and into the body to supply oxygen to working muscles or to the lungs for re-oxygenation.

The heart keeps on beating continuously in order to circulate the blood throughout the body. The change in the heart rate depends on the activity. It is lower in the state of rest or when asleep and faster during exercise.

During exercise, the heart rate increases because the blood has to deliver glucose and oxygen to the muscles and at the same time remove wastes from the same. This is controlled through the central nervous system. It directs the sympathetic nervous system to release epinephrine and norepinephrine. These hormones increase the heart rate.

At rest, the higher flow of blood is not required so the heart rate decreases. The parasympathetic nervous system releases acetylcholine which reduces the heart rate.

Note: The normal heart rate is 60-100 beats per minute. During strenuous physical work, it can go as high as 130-150 beats per minute. The heart rate also varies with age. The heart rate of children is around 70-100 beats per minute.