Functions Of The Skin Physiology Notes

Functions Of The Skin

The primary function of the skin is the protection of organs. However, it has many other important functions also.

1. Protective Function

Skin forms the covering of all the organs of the body and protects these organs from the following factors:

1. Bacteria and toxic substances
2. Mechanical blow
3. Ultraviolet rays.

Read And Learn More: Medical Physiology Notes

1. Protection from Bacteria and Toxic Substances

• Skin covers the organs of the body and protects the organs from having direct contact with the external environment. Thus, it prevents bacterial infection.
• The lysozyme secreted in the skin destroys the bacteria. The keratinized stratum corneum of the epidermis is responsible for the protective function of the skin.
• This layer also offers resistance against toxic chemicals like acids and alkalis. If the skin is injured, infection occurs due to the invasion of bacteria from the external environment.

During injury or skin infection, the keratinocytes secrete:

1. Cytokines like interleukins, a tumor necrosis factor, and γ interferon play important roles in inflammation, immunological reactions, tissue repair, and wound healing.
2. Antimicrobial peptides like p defensins prevent the invasion of microbes.

2. Protection from Mechanical Blow

• The skin is not tightly placed over the underlying organs or tissues. It is somewhat loose and moves over the underlying subcutaneous tissues.
• So, the mechanical impact of any blow to the skin is not transmitted to the underlying tissues.

3. Protection from Ultraviolet Rays

• The skin protects the body from ultraviolet rays of sunlight. Exposure to sunlight or to any other source of ultraviolet rays increases the production of melanin pigment in the skin.
• Melanin absorbs ultraviolet rays. At the same time, the thickness of the stratum corneum increases. This layer of the epidermis also absorbs the ultraviolet rays.

2. Sensory Function

• Skin is considered the largest sense organ in the body. It has many nerve endings, which form the specialized cutaneous receptors.
• These receptors are stimulated by the sensations of touch, pain, pressure, or temperature sensation and convey these sensations to the brain via afferent nerves.
• At the brain level, the perception of different sensations occurs.

3. Storage Function:Skin stores fat, water, chloride, and sugar. It can also store blood by the dilatation of the cutaneous blood vessels.

4. Synthetic Function:Vitamin D3 is synthesized in the skin by the action of ultraviolet rays from sunlight on cholesterol.

5. Regulation Of Body Temperature

• Skin plays an important role in the regulation of body temperature. Excess heat is lost from the body through the skin by radiation, conduction, convection, and evaporation.
• Sweat glands of the skin play an active part in heat loss by secreting sweat. The lipid content of sebum prevents the loss of heat from the body in a cold environment.

6. Regulation Of Water And Electrolyte Balance: Skin regulates water balance and electrolyte balance by excreting water and salts through sweat.

7. Excretory Function: Skin can excrete small quantities of waste materials like urea, salts, and fatty substance.

8. Absorptive Function: Skin can absorb fat-soluble substances and some ointments.

9. Secretory Function

• Skin secretes sweat through sweat glands and sebum through sebaceous glands.
• By secreting sweat, the skin regulates body temperature and water balance. Sebum keeps the skin smooth and moist.