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Circulatory System - The Heart - Coggle Diagram
Circulatory System - The Heart
The heart has four chambers - two atria and two ventricles
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 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.
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
the systemic circulation
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 walls of the left ventricle are thicker and contain more muscle than those of the right ventricle. This is to create more pressure on the blood ready for entering the systemic circulation.
Circulating blood
Blood passes through the heart twice in one complete circulation of the body.
Calculating how much blood is pumped by the heart
Calculating how much blood is pumped by the heart
Calculating how much blood is pumped by the heart. It can be calculated using the following equation: Cardiac Output = Stroke volume x Heart Rate