Excretion 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

Functions of the Excretory System:

Metabolism:

catabolism - the breaking down of things (ex. cellular respiration)

anabolism - the building up of things

What Metabolism is responsible for:

The reabsorption of molecules essential for normal body function (glucose, amino acids)

The elimination of harmful waste products and excess substances (excess water, urea)

These processes of reabsorption and elimination of substances are preformed by the nephrons located in the kidneys

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