Friday, December 28

Skin facts - Main functions of human skin

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Human skin has the major function of protecting the internal organs from external elements.
Being an organ of regulation, skin regulates several aspects of human physiology like fluid balance, body temperature, vitamin D synthesis, peripheral circulation, desquamation and immunological surveillance. Being an organ of sensation, human skin detects and relays main senses like heat, cold, touch and pain with the help of network of nerve cells present in it.

Barrier and protection

Being the natural barrier, skin protects the internal organs of the body from exposure to the natural elements and pathogens. Further it provides mechanical support to the body by covering and holding together the internal organs.

One of its main functions is two way water proofing. In normal healthy conditions it neither keep absorbing water and bloating nor losing water continuously and dehydrating. The natural layer of lipids, oil, cross linked keratin, corneocytes, salt and lipids from sweat and sebaceous secretions present on the outermost surface is the main defense from attacking bacteria and viruses.

Desquamation and self-healing

The outer layer of human epidermis is prone to physical damage and it has to be repaired continuously. It is continuously renewed by cell proliferation at dermis level and in epidermis the  outer most layers undergoing desquamation.

UV protection

The melanin pigment present in the skin, by filtering the Ultraviolet rays to some extent, protect it from sun damages and cancer.

Thermoregulatory functions

Sweat glands present in the human skin produce sweat (perspiration) in hot conditions.
By the effect of latent heat of evaporation it is cooled when the sweat evaporates.

Radiation

Excess heat from the body, as in the case of exercise or having fever, is radiated by the skin to the surroundings to stabilize and bring the body temperature down.
This is brought about by increase in blood supply to the dermis and dilation of dermal blood vessels.

Insulation functions

The human skin insulates the body to great extent by not allowing the body to lose heat and absorb cold from the surroundings.
Further by constriction of dermal blood vessels lesser amount of blood flows to dermis and heat loss is reduced.

Immunological surveillance

There are numerous specialized Langerhans cells present  which can identify harmful proteins and substances and take them to white blood cells and neutralize them.

Sensation

To bring about one of its main functions, nerve endings and special nerve cells in it contribute to the sensations like touch, pressure, vibrations, pain, cold and heat.
Though there are millions of nerve endings in it, their main concentration differs at different regions of the human body and some regions are very sensitive.

Main absorption functions

Skin can take in and/or release small amounts of gases like oxygen, carbon dioxide and nitrogen.
Oxygen is taken in and carbon dioxide is released out in small quantities to help in respiration.
Its absorbing capacity is utilized to send in medicines in the form of ointments and patches.
Various skin care and cosmetic products also get absorbed through it.
The main absorption functions can be either trans-cellular or inter-cellular.

Excretion

One of its main functions is the excretion of metabolic waste products and toxic substances like salt and urea.

Vitamin production

In humans, vitamin D synthesis is one of its main functions and in the presence of UV rays by chemical interactions with a naturally occurring lipid known as ergosterol, vitamin D is produced.

Storage functions

Lipids and water are stored in the epidermis to control loss of moisture from the body.
Excess lipids in the system are stored in the human skin.
Image source: http://en.wikipedia.org/wiki/File:Skin.png
Author: US-Gov
License: Public domain.

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