Sky Collins - Year 13 Biology Assessment Standard 91604
What is homeostasis and what does it do?
Homeostasis is the process of which an organism 's cells maintain it 's body 's internal environment and function-ability despite changes in it 's external environment. This is achieved through the work of the body 's homeostatic feedback mechanisms that sense the changes in the external or internal environment, such as with changes in temperature. The body of an organism has a balance that is set to a predetermined point of which the body is in a healthy, normal state, however when this balance is changed by a stimulus, either from outside of or within the body, the body uses homeostasis to return the equilibrium back to normal. Homeostasis
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temperature, C02 concentration, etc.) and turn on, or off, various internal systems in order to return the body to the set point. " - Homeostasis (page 33), Level 3 Biology Internal Scipad.
As seen in the diagram above, the body has a set point, a normal range of which the human body is considered healthy and capable of functioning. However, this can be imbalanced by the effects of increased or decreased blood glucose levels (BGL). It is necessary for the human body to maintain a relatively stable balance in it 's blood glucose levels, so when this balance is disrupted, the body acts to return it 's BGL back to the normal range, as if the body does not react to these fluctuations, it may be prone to developing diseases that may result in irreversible consequences on the body, or even death. The primary solutions to re-establishing the body 's BGL is through the work of the liver and pancreas. The pancreas secretes cells called alpha cells, these detect low BGL and in turn send glycogen (the stored form of glucose) into the bloodstream, travelling to the liver, which then converts the glycogen into glucose, then releasing it into the blood stream in order to level out the glucose and insulin levels in the blood (re-establishing blood glucose levels) back to the normal range. When BGLs are high, beta cells (which are also secreted by the pancreas) detect this change. They then release insulin into the blood, the insulin causes the liver to reabsorb excess glucose and convert it into glycogen, the stored form of glucose. Insulin also causes the body 's other cells to take up glucose so that it can be used up, thus lowering the BGL in the body back to the normal