Question

What is a myogenic heart? Describe the mechanism regulating the heartbeat in mammals.

Answer 1

Hint: It is the property related to continuous contraction and relaxation of the heart.

Complete answer:
The myogenic heart is the characteristics of vertebrates where continuous rhythmic contraction occurs. The myogenic heart is the intrinsic property of the cardiac muscles. Each contraction of the heart muscle regulates the flow of blood in the form of a pulse or heart rate.

The mechanism regulating the heartbeat in mammals.
1. The heart circulates the blood in different tissues of the body in the case of mammals.
2. Mammals have a four-chambered heart through which blood flows.
3. These chambers are divided as right atrium as the upper portion of the right side and the lower portion is right ventricle while the upper left portion is left atrium and the lower left portion is left ventricle.
4. The right atrium consists of the sinus node or a Sinoatrial (SA) node which acts as the pacemaker for the heart.
5. The functioning of the SA node and the regulation of the heartbeat is under the control of the body’s nervous system.
6. Each time the heart muscle contracts the blood will flow in the form of pulse or heart rate.

Note: Heart rate is controlled by the autonomic nervous system which is divided into two types – sympathetic and parasympathetic nervous systems. The sympathetic nervous system releases the hormones catecholamines – epinephrine and norepinephrine to accelerate the heart rate.
- The pulse rate is measured in beats per minute.
- Normal human being’s heart beats around 72 times in a minute.
- Exercises and stress may lead to an increase in heart rate as the flow of blood becomes faster to overcome the need for oxygen.