Both the oxygenated and deoxygenated blood in left and right atria enters simultaneously at same time or at diff time ?
Answers
hey,
Blood enters the heart through the atria. Blood from two vena cavae enters the right atrium. Blood from the pulmonary veins enters the left atrium.The atria fill, followed by the ventricles. Blood is prevented from flowing back into the atria by heart valves.
Blood leaves the heart in the body's main artery - the aorta - from the left side, and the pulmonary artery, from the right.
Double circulation
Humans have a double circulatory system. The heart pumps blood through two circuits:
the pulmonary circulation
the systemic circulation
The pulmonary circulation transports blood to the lungs. At the lungs:
oxygendiffuses into the blood from the alveoli - the blood becomes oxygenated
carbon dioxide diffuses from the blood into the lungs
Diagram showing how pulmonary circulation transports blood to the lungs
The systemic circulation transports:
oxygen and nutrients to the body
carbon dioxide and other wastes away from cells
The systemic circulation is under high pressure - it has to deliver blood to the extremities of the body.
The pulmonary circulation is under lower pressure, because:
blood is delivered to the lungs only, which are very close to the heart
in a healthy person, this lower pressure is optimum for the diffusion of gases
Diagram showing how blood is transported around the body
Circulating blood
Blood passes through the heart twice in one complete circulation of the body.
Following the blood through one complete circulation of the body:
Note that although this is shown as a sequence, the atria contract in unison, and when full, the ventricles also contract in unison. Part of the blood is being delivered to the body, while the remainder of the blood is being transported to the lungs. This means that oxygen can be picked up from the lungs, while at the same time, blood is also being delivered to the body.