Question

Define the process of regulation of heartbeat.

Answer 1

Human heart is a muscular organ composed of specialized cardiac muscles. Its main function is to pump blood. A single heartbeat is an unbelievably quick pumping action that takes about a second.

Complete answer:
As soon as the blood collects in upper chambers of the heart, i.e., the right and left atria, the Sino-Atrial (SA) node emits an impulse that contracts the atria; thus pushing the blood through the tricuspid and mitral valves into the resting lower chambers of the heart, i.e., the right and left ventricles. This 1st part of the two-part pumping action of the heart, is called “Diastole”.
The 2nd part starts as soon as the ventricles are filled with blood. The impulses from the SA node travel to the juncture of atrium and ventricle, which is known as the Atrio-Ventricular (AV) Node, through which the impulse moves to both the ventricles, via the Bundle of His, to the Purkinje fibers located in the ventricular walls, thus causing them to contract. This is called “Systole”.
As soon as the tricuspid and mitral valves shut tight to prevent the blood’s backflow, the pulmonary and aortic valves push open. When the blood is pushed from the right ventricle into the lungs to pick up oxygen, in the meanwhile, that oxygen-rich blood flows from the left ventricle to the heart and other body parts.
After the blood moves into the aorta and the pulmonary artery, the ventricles relax, and subsequently the pulmonary and aortic valves close down. Now, the lower pressure in the ventricles causes the mitral and the tricuspid valves to open, and the cycle begins all over again.

Additional information: The heartbeat is regulated by some intrinsic factors and extrinsic factors.
Intrinsic factor is the - “Sino-Atrial (SA) Node” located in the right atrium. It is called the “heart’s pacemaker”.
Extrinsic factors include - the hormones and the Autonomic Nervous System (ANS).

Note: A human heart beats approximately 72 times per minute (or anywhere between 60-80 times).
->Slow heartbeat is called “bradycardia” (induced by the parasympathetic nervous system).
->Fast heartbeat is called “tachycardia” (induced by the sympathetic nervous system).