Blood Glucose
Glucose is the fuel for the cells in the body. It requires insulin, a chemical released by the Pancreas, which in turn produces ATP (Adenosine Tri Phosphate) which is able to enter the cells. There are a variety of mechanisms responsible for glucose regulation. The liver, muscles and kidneys are all key players in the process. The liver is of major importance because of its ability to store glycogen to prevent low blood glucose levels in the body. Glycogen is a safe conversion of glucose suitable to be stored in the liver. The hormones insulin and glycogen, produced by the pancreas, are responsible for the homeostatic process (Crosier, Michael 2011).
Blood Glucose Concentrations:
Blood glucose concentrations in a healthy person are usually maintained at around 800 mg per dm3 in order to supply the brain and nervous system which cannot use any other form of energy. If blood glucose concentration drops below about 600 mg per dm 3 , a person suffers from hypoglycaemia which can rapidly cause loss of consciousness. Higher levels are required for any physical effort, but if too high levels can cause hyperglycaemia which causes lower water potential and draws water out of the cells. Circulatory shock can also occur because glucose is then lost in urine meaning excessive water loss in urine (Jones, Mary and Geoff 1997).
The Pancreas:
The pancreas is responsible in producing the hormones insulin and glucagon and the cells are arranged in patches called inslets of Langerhans. Within the islets, there are different types of cells, insulin is secreted by β cells, and glucagon by α cells. The α and β cells are able to sense the concentration of glucose in the tissue fluid around them, which is formed from the blood. They respond to changes in blood glucose concentration by switching on or off the secretion of glucagon or insulin (Jones, Mary and Geoff 1997).
Negative Feedback Loop:
The process in keeping the blood glucose levels at a constant level involves the negative feedback control, but this one is a little more sophisticated than others because it involves two hormones. The insulin brings about positive actions to bring down blood glucose levels, and glucagon brings about positive actions to stop them falling too low. If a human only had one of these hormones, insulin for example, then there would be a rapid response to bring the concentration down, but if it went to low it would just switch off and nothing would happen to bring it back up until the next carbohydrate-rich meal was consumed (Jones, Mary and Geoff 1997).
Type 1 and Type 2 Diabetes
Diseases that involve blood glucose levels are Type 1 and 2 diabetes. Type 1 diabetes, also known as insulin-dependent diabetes, is usually developed early in life and is caused by the B cells to secrete insulin because for a reason not quite understood the body’s immune system attacks and destroys the β cells, this is a biotic factor affecting homeostasis. This disease results is fats being metabolised more rapidly than usual resulting in the production of substances called ketoacids. These accumulate in the blood, lowering the pH levels, which is extremely dangerous as a person can die if the pH levels drop lower than 7.0. Types 1 diabetes patients have to regularly monitor their blood glucose levels by using biosensors or dipsticks, which is a behavioural factor involved in contributing to homeostasis.
Type 2 diabetes, or non-insulin dependent, is usually developed later in life and are more common in overweight people. In this disease the β cells can still produce insulin but often the decrease amounts and the target cells do not respond well to it. Both these diseases involve the blood glucose levels to be regularly monitored and diet carefully controlled (Jones, Mary and Geoff 1997).
Type 2 diabetes, or non-insulin dependent, is usually developed later in life and are more common in overweight people. In this disease the β cells can still produce insulin but often the decrease amounts and the target cells do not respond well to it. Both these diseases involve the blood glucose levels to be regularly monitored and diet carefully controlled (Jones, Mary and Geoff 1997).