Insulin from pancreas stimulates the cell to absorb glucose from the gut
As described in Cell Biology tutorials, the body requires volumes of glucose in order to create ATP. The amount of ATP demand fluctuates, and therefore the body regulates the availability of glucose to maximize its energy making potential.
Two hormones are responsible for controlling the concentration of glucose in the blood. These are insulin and glucagon. The diagram illustrates the principle of negative feedback control in action involving blood/sugar levels.
The liver acts as a storehouse for glycogen, the storage form of glucose. The effects of insulin and glucagon on the liver are as follows:
Diabetes insipidus is a condition where excess urine is excreted caused by the sufferer’s inability to produce ADH and promote the retention of water.
Diabetes mellitus is another form of diabetes wherein the sufferer does not have the ability to produce sufficient insulin. Without enough insulin, glucose cannot be converted into glycogen. Anyone who has this condition usually has to take injections of insulin after meals and snacks to maintain their storage of glucose needed in emergencies.
In emergencies, adrenaline is released by the body to override the homeostatic control of glucose. This is done to promote the breakdown of glycogen into glucose to be used in the emergency. These emergencies are often known as ‘fight or flight reactions’.
Adrenaline is secreted by the adrenal glands. The secretion of it leads to increased metabolism, breathing, and heart rate. Once the emergency is over, the adrenaline levels drop, and the homeostatic control of glucose is once again back in place.
The next tutorial investigates temperature regulation in homeotherms.
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