The following are the stages in one complete cycle of blood through the body:
1. Blood with little oxygen and a high concentration of carbon dioxide enters the right atrium through the venae cavae.
2. Blood is then pumped from the right atrium through a cuspid valve and into the right ventricle.
Right atrium Right ventricle Vena cava
3. The right ventricle contracts and forces blood up and out through a semilunar valve. The blood leaves the heart through the pulmonary artery.
4. The pulmonary artery delivers deoxygenated blood to the lungs. At the lungs, carbon dioxide is lost from the blood and oxygen is taken into the blood (gaseous exchange). The blood is now fully oxygenated.
136 Tissue cells Left atrium Left ventricle Lungs Tissue cells Vena cava Pulmonary artery Aorta Pulmonary vein Right
Right atrium
atrium
Cuspid valve
ventricle Left
Semilunar valve
Septum Left
Pulmonary vein
The heart acts as a pump to drive blood all over the body. It is located in the upper chest between the lungs. It is protected by the ribcage. The heart is made of very strong cardiac muscle that can continuously pump blood.
The heart is a double pump, separated into a left side and a right side by the septum.
There are four chambers in the heart. The left and right sides are further divided into upper atria (the right atrium and left atrium) and lower ventricles, separated by cuspid valves.
