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Excretion equation Excretion cleans up after respiration.

Respiration is a chemical reaction that takes glucose (sugar) and oxygen to produce energy. But it also produces water and carbon dioxide as bi-products.

Excretion gets rid of carbon dioxide, water, and other, possibly harmful, substances from your body.

Your lungs excrete carbon dioxide as you breathe out, your kidneys filter out nasties to produce urine, removing nitrogen waste from your body, and your skin sheds excess salt through sweat.

Lungs       Kidneys       Skin

All vertebrate animals produce nitrogen waste in one form or another.
The type of waste that is produced depends on where and how the animal lives.
Read on to find out more!

Jerboa Jerboas are desert mammals.
Like other desert animals they do not want to waste water by producing the amount of urine humans do - so their kidneys have adapted to reabsorb a lot of water, giving them very concentrated urine.

Birds do not want to carry around lots of water to make urine - it would make them too heavy to fly! Instead, they make a dry paste called 'uric acid' - you would know it when you saw it - it's the white stuff you see in their poo!

Bird poo

Remember there is one type of waste product that is not excreted from the body - poo! That's right, although it is a part of the body's waste, it is not a bi-product of your metabolism like urine is - it is expelled from the body, not excreted!

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