First 258 words of the document:
The circulatory system
The circulatory system is made of three main components. These are:
1. The heart
2. The blood
3. Blood vessels
Deoxygenated blood enters the right atrium. Oxygenated blood from the
lungs enters the left atrium. The right atrium contracts to push blood through
the tricuspid valve into the right ventricle. The left atrium contracts to push
oxygenated blood through the mitral valve into the left ventricle. Right ventricle
contracts to open the semi lunar valve opens and deoxygenated blood travels
back into the lungs. Left ventricle contracts the semi lunar valve opens and
oxygenated blood travels back around the body again.
The valves in veins are to stop blood flowing backwards. The septum splits
the heart into two sections one for oxygenated one for deoxygenated. Veins
carry blood into the heart and carry deoxygenated blood (apart from the
pulmonary vein). Arteries carry blood away from the heart and carries
oxygenated blood. The double circulatory system has two separate circuits
and blood goes into the heart twice.
There are three types of blood vessels. These are:
The blood has four components. These are:
2. Red blood cells
3. White blood cells
The pressure against artery walls.
The number of beats per minute
The volume of blood pumped from the heart with each beat.