Biology Exctretion Notes

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BIOLOGY:

EXCRETION

Secretion: the release of useful substances formed in the cells of the body (ie. enzymes like salivary amylase in saliva and hormones like adrenaline)

Defaecation/Egestion: the elimination of undigested food from the body via the anus (faeces consists of substances that were not formed in the bodies cells)

Excretion: the removal of harmful waste products, excess water and salts and foreign substances such as drugs and preservatives

Excretory organs include :

THE KIDNEYS - urea, uric acid, creatinine, ammonia, excess water, mineral salts

THE LUNGS - carbon dioxide and water vapour

SWEAT GLANDS - urea, water and mineral salts

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