Homeostasis in Living Things

3.1 Homeostasis in Living Things

3.1

Homeostasis in Living Things

Definition

Homeostasis refers to the maintenance of the internal environment in the body of an organism

Homeostatic Control Process

The importance of homeostasis in the human body:

Regulation of Water Content

Regulation of Body Temperature

Suhu normal \((37^\circ\text{C})\)

The condition of skin layer during higher and lower surrounding temperature:

Higher surrounding temperature

Sweat glands produce more sweat to cool the skin when sweat is evaporated.
Hairs lie flat to reduce air trapped on the skin so that heat can be released easily.
Blood vessels dilate to let more blood flow close to the skin to increase heat loss

Lower surrounding temperature

Erect hairs trap a layer
of air that acts as a heat insulator.
Blood vessels constrict to let more blood flow away from the skin to reduce heat loss.

Homeostasis in Animals

Example of animals	Ways of homeostasis
Cat	Lick fur to reduce body temperature
Dog	Hang the tongue to reduce body temperature
Lizard	Cold surrounding Body activities become slower Muscles function more slowly Movements become slower Metabolism rate decreases Body temperature decreases Hot surrounding The heart beats faster Movements become faster Metabolism rate increases Body temperature increases
Snail	Produces fluid and looks for humid places to reduce water loss.
Bee	Closes spiracles between two breathing movements to reduce water loss.

Homeostasis in Plants

Definition

Transpiration is the water from leaves in the form of water vapour to the surrounding through stoma.

Transpiration helps plants to absorb and carry water and minerals from the soil to all parts of the plant.
Evaporation of water from the leaves cools the plant during hot days.

Definition

Stoma is guard cells control the opening and closing of stoma

During the day: stoma opens to enable more water to be evaporated from the leaves through transpiration.

During high temperature: stoma closes to reduce water evaporated from the leaves through transpiration.

The importance of homeostasis to humans and living things:

Provide the optimum conditions in the body
The internal environment in the body is regulated and maintained in a balanced and stable condition.

Quick Notes