Tuesday, 4 May 2010

Describe the components of plasma and explain their functions.

Plasma is made up of mainly water, but it also carries Red blood cells, white blood cells, platelets, carbon dioxide, urea, hormones, antibody's and antitoxins and nutrients such as amino acids and glucose.
Red blood cells.
These carry oxygen from the lungs to all the cells in the body, in the form of oxyheamoglobin. They also carry carbon dioxide back to the lungs from the cells to be expirated.
White blood cells.
White blood cells defend the body against disease. They do this by consuming bad micro organisms and by producing anti body's that fight bacteria and anti toxins that neutralise toxins that bacteria have secreted into the body.
Platelets are very small bits of cells. They float around in plasma and are needed to help the blood clot and form a scab which stops the loss of blood and prevents infections from entering the body.
Urea is secreted by the liver and is excreted in small amounts in sweat and also in urine.
Hormones are 'chemical messengers' that are carried in the blood. They are produced by the endocrine glands and only have an effect on target cells.
These are needed by the body to repair it and to provide energy.
Some substances dissolve into the water in the blood and are carried in 'solution' and some do not dissolve and are carried in 'suspension'.
CGP Handouts
Edited by:-Parsons.R,Undated,GCSE Double Science Biology The Revision Guide Higher Level,Newcastle upon tyne, Coordination Group Publications LTD.

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