Functions of the Skin

The important functions of the skin include:

1. Protection: The skin protects the body against entrance by microbes, mechanical injuries, ultra-violet rays of the sunlight and desiccation by acting as waterproof. The pigment, melani absorbs ultra-violet rays from the sun which is harmful to the body.


2. Sensitivity: The skin is sensitive to its stimuli as touch, changes in pressure, temperature, pain and code. This makes us aware of the changes in our surroundings so that we can take the necessary actions for our well-being and survival.

3. Excretion: The skin excretes excess water, mineral salts and some nitrogenous wastes as sweat through the sweat gland.

4. Storage of food: Fats are stored under the dermis of mammals. Fats so stored form an insulating layer.

5. Production of milk: The mammary glands in female animals that are modification of the skin produce milk which are used to feed the young ones.

6. Production of vitamin D: The skin is able to manufacture vitamin D by using infra-red rays from the sunlight.

7. Regulation of body temperature: Animals are able to regulate their body temperature in their various habitats and environment. Based on body temperature, vertebrates are grouped into two categories:

1. Poikilothermic animals: These are animals whose body temperature varies according to the temperature of the environment, i.e, their body temperature is never constant. Examples of these animals are: fish, reptiles such as snake, amphibians such as frogs and told, etc.
2. Homoiothermic animals: These are animals whose body temperature remain constant regardless of the changes in the temperature of their external environment. Examples of these animals are birds and mammals including man.

HOW THE BODY REGULATES ITS TEMPERATURE

The mammalian skin helps to regulate the body temperature in specific ways as explained below.

On hot day, weather or environment

On a hot day, weather or environment, a mammal keeps its body temperature constant. A rise in body temperature as a result of rise in environmental temperature stimulates the following processes to get rid of excess body heat:

1. Vasodilation: The capillaries near the skin surface dilate, while those in the deeper layers of the skin constrict. This causes a large volume of blood to flow near the surface of the skin so that heat is lost to the surroundings via conduction, convection and radiation.
2. Sweating: In humans, the sweat glands become active and produce large amounts of sweats that flow out onto the surface of the skin. As this sweat evaporates, heat from the body is used up, thus cooling the body.
3. Decreasing metabolic rates: The body slows down its activities to reduce the metabolic rate. This reduces the heat released by metabolic reactions, hence heat production within the body is reduced.
4. Lowering of hairs: In a hairy mammal, the hair erector muscles relax, causing the hair to lie flat on the skin surface. This forces out most of the hair trapped among the hairs. Without the insulating layer, the animal loses more heat from its body.
5. Behavioural changes: Many mammals keep cool by staying in the shade. Human beings wear tight clothes with light coloured absorbent material.

On a cold day, weather or environment

On a cold day, weather or environment, a mammal is able to keep its body temperature constant. A fall in body temperature as a result of a fall in environmental temperature stimulates the following processes to produce and conserve heat:

1. Vasoconstriction: The capillaries near the skin surface constrict, while those in the deeper layers dilate. This causes a smaller volume of blood to flow near the surface of the skin so that heat loss is greatly reduced. This conserves the body heat.
2. Sweating: In human, the sweat glands become inactive and produce very little sweat that flows out to the skin surface. As a result, heat loss through evaporation of sweat is drastically reduced, thereby conserving body heat.
3. Increasing metabolic rate: The body increases its metabolic rate, especially that of the liver, to produce more heat. Shivering is also aimed at increasing the body's metabolic rate. Physical activities, such as running, clapping or moving when we feel cold, help to produce heat.
4. Raising of hairs: In hairy mammals, the hair erector muscles contract to raise the hairs and trap more air. Since air is a bad conductor of heat, the layer of air next to the skin acts as an insulator and prevents heat loss from its body.
5. Behavioural changes: Many mammals keep warm by staying in nests and huddling into a ball to reduce surface area. Human beings wear woolen clothing, jacket or coat

Recommended: The skin and its structure

Recommended: Care of the skin

Categories: Biology, Excretion, Excretory System, Homeostatis, The skin