3.1 Hemeostasis in Living Things - Homeostasis in Plants

3.1 Hemeostasis in Living Things 
■ Homeostasis is a process of regulating the internal environment of the body to be in a balanced and stable condition.
■ Homeostasis using corrective mechanisms.

Audio: Homeostasis using corrective mechanisms.



Homeostasis in Human Body
■ 70% of our body mass is water.
■  Every day, a large amount of water is lost from the body which needs to be replaced.
■  Excessive loss of water makes us feel thirsty and this can be fatal in the long term.
■  Our body temperature needs to be always maintained at 37°C
■  An extra 6°C rise in the body temperature can affect the functions of body cells and this can cause death.
■  Therefore, regulation of water content and body temperature are important homeostasis to sustain life.

Regulation of Water Content
■ The systems involved in the regulation of water content are excretory system and endocrine system.
■ Regulation of water content in the body can be achieved by controlling the volume of
urine production from the kidneys using corrective mechanisms.


Audio: Increase in Water Level
1. When we drink a lot of water and sweat less, the water content in our body will increase.
2. The increase in water level in our body is detected by the brain and corrective mechanisms occur to stimulate the secretion of a hormone so that the kidneys will increase the urine production.
3. As a result, high volume of diluted urine will be produced. Hence, the water level in the body will decrease to the normal level.

Audio: Decrease in Water Level
1. On the other hand, when we drink less water or sweat a lot, the water content in our body will decrease.
2. The decrease in water level in our body is detected by the brain and corrective mechanisms occur to stimulate the secretion of a hormone so that the kidneys will reduce the urine production.
3. As aresult, very less and concentrated urine will be produced. The water level in our
body will increase to the normal level.

Regulation of Body Temperature
■ The skin in the excretory system and hormone secreted by the endocrine system play an important role in regulating the body temperature.


2 When the body temperature deviates from 37°C , the change in the body temperature will be detected by the brain and corrective mechanisms will act to restore the body temperature to the normal range.
3. Corrective mechanisms control the production of heat and loss of heat which involve the actions of blood vessels, sweat glands, hairs, skeletal muscles and hormone.
4. In a hot surrounding or during exercise, heat los will increase and heat production will decrease. Hence, the temperature wl decrease and return to normal.
5. On the other hand, when the surrounding is cold, the heat production will increase and heat loss will decrease. So, the temperature will increase and return to normal.

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