Monday, January 4, 2010

The Circulatory System





  • To carry digested food from the small intestine to all areas in the body which need it.








  • To carry oxygen from the lungs to the rest of the body.








  • To aid in the disposal of all wastes from the body.








  • To distribute heat.








  • To fight diseases by using white blood cells to fight off infection.








  • Click to see a large version of the picture over. Click on back to get back here!




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The blood is made up of different types of cells and a liquid medium for which they are transported. The cells in the blood are Red Blood Cell (Corpuscles), White Blood Cells and PlateletsPlasma is the liquid medium of blood. Red Blood Corpuscles are technically not cells at all, as they do not contain a nucleus. Their red colour is from a substance known as haemoglobin.Blood separated into its constituents.
Haemoglobin binds with oxygen so it is the red blood corpuscles that carry oxygen in the body.
White Blood Cells are largest and not as plentiful in the blood as corpuscles. These cells are used to fight infection.Foreign bodies are either devoured by the cells or the cells produces antibodies, which in turn attack the infection.Platelets are small fragments of cells, and are responsible for blood clotting. A Haemophiliac (someone who cannot clot) doesn’t have any platelets.
Plasma is the medium in which all the cells are maintained. It contain water, proteins (fibrinogen), food, wastes (e.g. CO2), Antibodies and Hormones.


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The heart is a four-chambered hollow muscle, used to pump blood all over our bodies.
It is divided into four compartments, the left and right ventricles and the left and right atria (atrium in singular).
  The right side of the heart pumps blood low in oxygen (de – oxygenated) to the lungs.
The left side of the heart pumps blood rich in O2 (oxygenated blood) all over the body.



Blood enters the heart through the superior and inferior Vena Cava and into the right atrium.The tri-cuspid valve opens and the blood is moved into the right ventricle.
The walls of the right ventricle contract and the blood is pumped up to the lungs (through the pulmonary artery) where oxygen replaces CO2 in the blood.
The oxygenated blood enters the heart from the lungs through the left atrium (via the pulmonary vein).
Again a valve opens and the blood moved into the left ventricle.
The walls of the ventricle contract and the blood is pumped all over the body via the Aorta.
The rate of beat is controlled by the pace maker in the septum.

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