Homeostatic Control of Blood Glucose Levels

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Adnan Undre

Homeostatic Control of Blood Glucose Levels

Glucose is an essential substance in the body as it the primary source of energy for all biological functions and is indeed the only form of energy which can be used by the brain and central nervous system. The ideal level of blood glucose is 80 - 90mg of glucose per 100mls of blood. However this level is not static - it oscillates due to changes in the body which are brought about by actions such as eating a meal, exercising, or not eating for long periods. If blood glucose levels drop or rise dramatically there may be serious consequences such as hypo- or hyperglycaemia which can both cause death. Thus it is necessary for blood glucose levels to be regulated and this is achieved through homeostasis. To work effectively homeostasis requires an effective receptor to detect variations from the norm and a negative feedback system where antagonistic processes work to redress any variations as they occur. By examining the mechanisms of the homeostatic control of blood glucose levels it should be possible to explore the consequences of a breakdown of this part of the endocrine system.

Essentially, blood glucose levels are controlled by the pancreas. It is in this organ that areas of cells called the Islets of Langerhans exist, which consist of alpha cells and beta cells. These cells monitor blood glucose and secrete the hormones glucagon and insulin respectively. Glucagon and insulin regulate blood glucose levels through their antagonistic and opposite effects in a system of negative feedback.
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The most important effects of insulin work to lower blood glucose levels, which may be too high following a large, carbohydrate heavy meal for example and are as follows. Blood glucose levels are reduced by the liver and muscle cells being stimulated to take up more glucose and convert it to glycogen which is insoluble; the production of glucose from protein and fats (gluconeogenesis) is reduced; cell membranes increase in their permeability to glucose, therefore more glucose is taken out of the blood and into the cells (increasing respiration). The level of blood glucose is constantly monitored by ...

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**** A good overview of blood glucose regulation and diabetes using A level biological terminology correctly throughout. The role of negative feedback has been neglected however.