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Glucose is needed for respiration so if the level falls below this, the normal body activities may not be able to continue. If the level rises too much the normal behaviour of cells is affected and serious problems can arise. The ideal level of blood glucose is about 1mg/cm3.
There are natural situations that can affect the level of glucose. For example, eating will increase it and exercise will decrease it. Because of this fluctuation, there are 2 hormones that minimise these fluctuations in glucose levels. Their names are insulin and glucagon and they work antagonistically (against each other). Both are produced in the pancreas; α cells of the pancreas produce glucagon, β cells of the pancreas produce insulin.
Glucose is a small, soluble molecule that is carried in the blood plasma. The pancreas detects the level of glucose and the appropriate hormone is released to either increase or reduce the level of glucose.
In the next section you need to be very careful as the words used are very similar and can be confusing.
Try looking at the start of the words to see if it is referring to Glyco or Gluco and then at the ends of words to see if it is referring to genesis (meaning formation) or lysis (meaning splitting).
Note: Neogenesis means new formation.
Insulin reduces the level of glucose in the blood plasma by:
Using up the excess glucose (this is done by increasing the rate of respiration).
Increasing the amount of glucose absorbed into the body cells (particularly the liver) thus taking the glucose out of the blood plasma.
Turning the glucose into glycogen. This process is called Glycogenisis (remember, genesis means formation).
Glucagon increases the level of Glucose in the blood plasma by doing roughly the opposite to insulin...
Slowing the use of glucose (this is done by reducing the rate of respiration).
Reducing the amount of glucose absorbed into the body cells (particularly the liver).
Releasing glycogen. Glycogen is stored in the liver and muscles and is easily converted into glucose in a process called Glycogenolysis (remember, lysis means splitting).
In addition to this, Glucagon promotes the conversion of fatty acids. into glucose. This process is called Gluconeogenesis (remember, neogenesis means new formation).
This illustration shows the process your body goes through to react to changes in glucose levels: