Question

Explain “double circulation of blood through the heart”.

Answer 1

Double circulation of blood through heart is nothing but the two type of circulation viz, pulmonary circulation and systemic circulation.

Pulmonary circulation:

It is the movement of blood from heart to lungs and back to heart again.

It is one phase of the overall circulatory system.

HEART – LUNGS – HEART

Systemic circulation:

It is a process in which oxygenated blood is carried from the heart to all parts of the body and deoxygenated blood is carried from all   the body parts back to the heart.

It is the major part of the overall circulatory system

HEART – BODY PARTS – HEART

Answer 2

The circulatory system can divide in to first order circulatory system and the second order circulatory system. In first order circulatory system the blood is pumped to the lungs for acquiring the oxygen and the release of the carbon dioxide. Once the blood is oxygenated it enters the second order circulatory system by pumping blood to different organs of body and the brain. The Second order blood gets deoxygenated by the organs as they take oxygen from it, and thus blood once again enters heart and enters the first order system again.

There are two different systems involved in the double circulatory system. The amphibians, birds and mammals including humans have this double circulation. The fish have single circulation system, as there are no lungs in fish. The animal living above the water level generally has this double circulatory system for getting the benefit of direct oxygenation.

There are two separated pumps or flow circuit in the adult human heart. The one side of the heart is dedicated to the right atrium and right ventricle. This system pumps the deoxygenated blood in the pulmonary circulation. There is low pressure in the circuit. The system has left circuit consisting of the left atrium and left ventricle. This system pumps the oxygenated blood in the systemic circulation. This system has high pressure compared to the right circuit. The blood from the one circuit goes another circuit through the heart.