The Kidneys

What 3 ways can the body lose water?

• Via the lungs when we exhale.

• Via skin when we sweat. Sweat also contains ions such as sodium and also urea.

• Via the kidneys in urine.

What happens if the blood is too dilute?

The kidneys remove the excess water and they produce a greater volume of urine.

What is also removed in urine besides excess water?

Urea and excess ions.

How does blood enter the kidney?

Through the renal artery (blood contains urea)

What does the kidney do once blood has entered it?

The kidney removes the urea as well as the excess water and excess ions.

How does the urea, excess urea and excess ions leave the kidneys?

They leave as urine and this is stored in the bladder.

Leave through the renal vein.

What happens in the capillaries in the kidney?

Small molecules are filtered out of the blood - urea, ions and water, as well as glucose.

What happens to these small molecules?

They are passed into a tube.

What happens during selective absorption?

• All of the glucose is reabsorbed

• Some of the ions are reabsorbed

• Some of the water is reabsorbed.

What are proteins made up of?

Chains of amino acids.

What happens when we digest proteins?

Amino acids pass into the bloodstream.

What happens to excess proteins that we don’t need?

• Liver breaks down the excess amino acids and produces the chemical ammonia.

  This is deamination.

What is important about ammonia?

It is a very toxic chemical so the liver immediately converts it to urea.