What is the structure and function of human skin?

Did you know that the skin is your body’s largest organ?  The skin covers the whole body and has a total area of approximately 20 square feet. It has three major layers namely the epidermis, the dermis, and hypodermis (subcutaneous layer). Each layer is very essential so as to remain in good health.

The epidermis: this is the skin’s outermost layer. It is elastic and is constantly being renewed. It gives the skin its tone and offers a water-proof barrier. The epidermis includes; Melanocytes- these are cells responsible for producing the pigment called melanin that gives the skin its color and offers it protection against ultraviolet (UV) radiation. Keratinocytes — these are the major cells of the epidermis and are formed through cell division at its base. New cells continuously travel towards the surface and as they do so, they slowly die and get flattened. Corneocytes: these are the dead keratonytes cells that collectively form the outer layer of the epidermis referred to as stratum corneum layer. This layer is a protective layer and is constantly being shed.

The dermis: this is the inner layer of the skin, located below the epidermis. It includes; Sweat glands- they are responsible for producing sweat.

Sweat travels through sweat ducts toward openings in the epidermis known as pores. Sweat glands help in regulation of body temperatures.

Hair follicles- these are the pits in which hairs develop. Hairs also play an important role of regulating body temperatures.

Sebaceous glands- these glands secrete an oily substance called sebum that protects the hairs from bacteria, dust and gives waterproof barrier to the skin. Sweat and sebum form the surface layer.

The subcutaneous layer: it found beneath the dermis. It is composed of connective tissues that join other skin structures and fat, which acts as a good insulator.

The skin plays vital functions of which in their absence, survival would be difficult. Some of the skin functions include;

 Regulation of temperature: when it is hot, the skin usually acts by releasing sweat from the sweat glands so as to cool the body down. When it is cold, the small blood vessels in the skin can get filled with blood to make you feel warmer. Normally, the retention or release of heat is determined by the body’s temperatures.

 Giving body protection:  the skin protects the body in various ways. For example, the melanin pigment in the skin offers protection against harmful UV radiation. The skin gives protection to inner tissues, organs, and bones so that they are not exposed to outside environment.  The skin also protects the body from bacteria attack and physical trauma.

 Allowing growth and movement: the skin and the tissues below it have elastic characteristics that allow the body to grow and move more easily. Body movement would be painful or not be possible at all if the skin were hard and rigid.

 Immunity:  The skin has some cells like phagocytic and epidermal dendritic cells that work together with the immune system to fight viruses, bacteria, and other harmful things that settle on the skin. The skin acts by preventing these things from making their way into the body hence causing diseases.

 Excretion of waste: in one way or another, the body needs to eliminate waste products. Waste such as uric acid, water, and urea can be excreted via the skin. By doing this, the body is able to get rid of substances that might make a person sick.

 Sensation: the skin is overly sensitive, a characteristic that allows a person to feel even the least changes in pressure and temperature. The body has nerve endings that react to sensation felt by skin, hence instantly alerting the brain of the new feeling. Therefore, a person is able to react to pain, injury, cold or hot, and even mild touch.

Other skin functions may include absorption of nutrients, synthesis of vitamin D, and prevention of water loss, among others.