Homeostasis overview

Homeostasis is the maintenance of a constant internal environment

All of our cells are bathed in a watery solution, which is formed by some of our blood plasma which is allowed to leak out of our blood. This carries away any waste materials back into the blood.

The balance of things in this tissue fluid is critical for the cells and the whole body. There are basically 6 things that are essential for health and that must be controlled:

1. Carbon dioxide
Extra carbon dioxide must be removed, otherwise the body becomes too acidic. It is lost mainly in the air we breathe out, but a small amount is lost in the urine.

2. Urea
This is the waste chemical produced when we digest amino acids in the liver. It is poisonous and so must be removed. This is done mainly through the urine, although some is lost through our sweat.

3. Ions
If the right balance of ions is not kept, our cells can become shrivelled, swollen or even burst!
Important ions include sodium, potassium, hydrogen and phosphate. These are controlled through our urine and the amount of water we drink. We also lose some, like sodium ions, through our faeces and our sweat.

4. Sugar
Having enough glucose for respiration plus adequate storesof glycogen is critical. If the blood glucose level falls too lowwe will die.

5. Water
Seventy percent of our body mass is water. Without keeping the right amount of water we would die. The kidney is the key means of this control (see later).

6. Temperature
The enzymes that control every chemical reaction in our body work best at their optimum temperature of 37 degrees Centigrade. If our body cells get too hot or too cold they would die. So would we!