Homeostasis

Science

Homeostasis

The conditions inside the body must be controlled within narrow limits. This is called homeostasis. These conditions include water content, ion content, body temperature and blood glucose concentration.

The thermoregulatory centre is the part of the brain that monitors and controls body temperature. The pancreas meanwhile monitors and controls blood glucose concentration. It produces a hormone called insulin that reduces blood glucose levels. Diabetes is a disease which can be caused by insufficient insulin.

Removing waste products

Waste products must be removed from the body. If they are not, they will increase in concentration and may interfere with chemical reactions or damage cells. Waste products that must be removed include carbon dioxide and urea.

Production and removal of waste products

Waste product Why is it produced? How is it removed?

carbon dioxide it is a product of aerobic respiration through the lungs when we breathe out

urea it is produced in the liver when excess amino acids are broken down the kidneys remove it from the blood and make urine, which is stored in the bladder temporarily

Water enters the body through food and drink. It is also a product of aerobic respiration in cells. If the amount of water in the body is wrong, cells can be damaged because too much water enters or leaves them. The animation shows how the amount of water lost as urine is controlled. Note that you do not need to know any details of this for the examination.

Controlling blood glucose

You found out in your GCSE Science Biology 1 studies that the blood glucose concentration is controlled to provide cells with a constant supply of energy. You might want to check your understanding of this by looking at the section in Bitesize AQA GCSE Science about Hormones.

The pancreas and insulin

The pancreas [pancreas: large gland located in the abdomen near the stomach which produces digestive enzymes and the hormone insulin ] monitors and controls the concentration of glucose [glucose: a simple sugar made by the body from food, which is used by cells to make energy in respiration ] in the blood. It produces a hormone called insulin [insulin: A hormone that regulates the level of sugar in the blood. It is produced in the Islets of Langerhans, in the Pancreas. ]. Insulin causes glucose to move from the blood into cells. It lowers the blood glucose concentration if has become too high. This can happen after eating a meal that is rich in carbohydrates (for example, sweets, potatoes, bread, rice or pasta).

The animation shows how this works.

Diabetes

Diabetes is a disease where the concentration of glucose [glucose: a simple sugar made by the body from food, which is used by cells to make energy in respiration ] in the blood is not controlled properly by the body. In type 1 diabetes, the pancreas [pancreas: large gland located in the abdomen near the stomach which produces digestive enzymes and the hormone insulin ] does not produce enough insulin [insulin: A hormone that regulates the level of sugar in the blood. It is produced in the Islets of Langerhans, in the Pancreas. ]. This can lead to high levels of glucose in the blood, which can be fatal.

Banting and Best

You should be able to evaluate experimental data from Banting and Best's experiments which led to insulin being discovered.

Two doctors, Frederick Banting and Charles Best, made an extract from the pancreas in 1921. The extract had anti-diabetic properties, and they tested it successfully on diabetic dogs. The first tests in humans were carried out in 1922, and were a success too. Some patients who were in a diabetic coma even recovered. The extract contained the hormone insulin.

Diabetes

There are two types of treatment for diabetes:

Careful