EXCRETION

What is excretion?Excretion is the process of removing metabolic waste products and other toxins.

What is

metabolism?

Metabolism (from Greek: μεταβολή metabolē, "change") is the set of life-sustaining chemical transformations within the cells of living organisms. These enzyme-catalyzed reactions allow organisms to grow and reproduce, maintain their structures, and respond to their environments.

Raw Materials (Food and 02)

Useful Materials Useless Materials

Egested (faeces) Metabolised

Metabolic Waste Products (urea and CO2)

Excreted

Useful Products

What are metabolicwastes?

carbon dioxide

water

ammonia

urea

uric acid

These waste productscan damage the cellsas they are mostlytoxic

• There are four main excretory organs:– Lungs

– Colon

– Skin

– Kidneys

Kidneys

What do the kidneys do?

Extracts metabolic wastes from the blood stream andeliminates it from the body

Adjusts blood ph by excretion of more or less acid

Adjusts blood salt concentration by excretion of moreor less salt

Adjusts bloodvolume and blood pressure bysecretion ofrenin(a hormone)

Stimulates red blood cell production by excretion oferythropoietin (another hormone)