Controlling internal conditions
The processes in your body that help to maintain a constant internal environment are known as homeostasis.
Your body has to cope with different temperatures and with varying rates of respiration.
- Carbon dioxide is a waste product of respiration, it is excreted through the lungs.
- Some of the amino acids we take in are not used. They are converted into urea by the liver and excreted by the kidneys in the urine. Urine can be stored in the bladder.
- The water and ion content of cells must be carefully controlled. If they are not, then too much or too little water may move in and out of cells by osmosis.
We must remove the waste products produced through chemical reactions from the body.
There are other factors we must keep within certain limits, e.g. water and ion content of the cells.
Controlling body temperature and blood sugar
Controlling body temperature - The thermoregulatory centre of the brain and receptors in the skin detect changes in temperature. The thermoregulatory centre controls the body's response to a change in internal temperature.
Enzymes work in a very narrow temperature range. We must keep our body temperature within that range.
Controlling blood sugar - The pancreas monitors and controls the level of sugar in our blood. If there is too much sugar in our blood the pancreas produces the hormone insulin that results in the excess sugar being stored in the liver as glycogen. If insulin is not produced the blood sugar level may become fatally high. If the pancreas is not producing enough insulin, this is known as diabetes. It can sometimes be controlled by diet or the person may need insulin injections.
The level of sugar in the blood must be kept at the correct level. Hormones help us to do this.