1. What is homeostasis?
-The ability of the body to maintain different internal parameters at a certain level such that it can be kept at its best condition.
2. What are the examples of these internal parameters?
(1) body temperatures
(2) water content in blood
(3) gas content in blood
(4) blood glucose level
3. What is the principle of the negative feedback mechanism?
(1) A receptor detect a change in parameter, it sends signal to the
control centre.
(2) The control centre receive the signals, coordinates the activities of different organs, and send instruction to the effector.
(3) The effector produce a response that restore the parameter to normal level.
4. Using a rise of blood glucose above normal level as an example, describe how the body achieve homeostasis.
(1) When blood glucose level rises above the normal level, the rise is detected by the chemoreceptors of the pancreas,
(2) The pancreas (pancreas is both the receptor and the control centre)
secretes more insulin,
(3) Insulin travels through blood and stimulate the liver to convert glucose in the blood to glycogen.
(4) Insulin also stimulates all body cells, especially muscles cells, to absorb and breakdown glucose.
(5) Blood glucose level falls back to normal level.
5. Using a fall of blood glucose below normal level as an example, describe how the body achieve homeostasis.
(1) When blood glucose level falls below the normal level, the fall is detected by the chemoreceptors of the pancreas,
(2) The pancreas (pancreas is both the receptor and the control centre) secretes more glucagon,
(3) Glucagon travels through blood and stimulate the liver to convert glycogen to glucose which is then released to blood.
(4) Blood glucose level rises back to normal level.