Dermatologist : The structure and function of the skin ( Complete Guide )

Dermatologist : The structure and function of the skin ( Complete Guide )

It is essential to have some background knowledge on the normal structure and function of any organ before you consider abnormalities.

The skin is often referred to as the largest body organ and serves as the main protective barrier against damage to internal tissues from trauma, ultraviolet light, temperature, toxins and bacteria. The skin is also responsible for sensory perception, temperature regulation, production of vitamin D and excretion of waste products. In addition to preventing harmful substances from entering the body, it also controls the loss of vital substances from the body. It is therefore important that the skin remains intact to allow the body to perform these essential functions.

The skin contains a number of accessory organs which assist in its protective role. As we can see in Fig. 1, it consists of two main layers: the epidermis, or outer layer, and the dermis, which lies beneath the epidermis.

The thickness of the skin varies depending on the site, with thicker skin being present on areas of the body that experience friction or wear and tear, such as the soles of the feet and palms of the hand.
The skin is supported by a layer of fatty tissue, sometimes known as the hypodermis. This fatty area helps to act as a cushion to protect the body and is also important for insulation.

The Epidermis

The epidermis (outer layer) contains no blood vessels and is divided into five layers. Cells move from the base of the epidermis up to the surface, changing shape and structure as they go. The epidermis is made up of stratified squamous epithelium or hardened cells which play a role in the  skin’s protective function. This is referred to as the stratum corneum.

Epidermal cells line the hair follicles, sebaceous glands and sweat glands. A number of projections which reach down from the epidermis to the dermis can be found at the point at which they join. These are called rete pegs, which help to maintain skin integrity when the skin is under stress.

 Melanocytes are cells found in the deepest layer of the epidermis. They produce melanin, which helps protect the body from the sun’s harmful rays.

The dermis

The main function of the dermis is to provide physical support and nutrients to the epidermis. The two layers identified within the dermis are the papillary layer and the reticular layer. Key substances found in the dermis include elastin, fibrillin and collagen (which helps give support and protection), all of which will decrease with age.

The dermis also contains nerve endings, sweat glands, sebaceous glands, hair follicles and blood vessels. The papillary dermis contains smaller blood vessels which supply oxygen, elastic fibres and nutrients to the lower epidermis.

The nerve endings sense pain, touch, temperature and pressure and are a vital part of the body’s protective mechanisms. There are more nerve endings in certain parts of the body, such as the fingertips and toes Sweat glands produce sweat, which contains some body waste products, water and salt. Evaporating sweat causes cooling of the body. Sweat from the axilla and groin areas (apocrine glands) is more oily in nature and produces a characteristic odour when digested by the skin bacteria.

Sebaceous glands secrete sebum into hair follicles. Sebum is an oily substance that keeps the skin moist and acts as a barrier against foreign substances. Hair follicles produce the various hair types that can be found around the body, so can affect a person’s appearance. Hair is also involved in protecting the body from injury and can improve sensation.

The blood vessels within the dermis are involved in temperature regulation. The thicker reticular dermis contains dense connective tissue, larger blood vessels, elastic fibres and bundles of collagen arranged in layers.

Also within the reticular layer are the following key cell types:

• fibroblasts − a key cell involved in repairing tissue damage

• mast cells − which are involved in fighting infection

• lymphatic vessels – the lymphatic system is a key part of the body’s defence against infection

• epidermal appendages or rete pegs – as explained above, the epidermis and dermis are linked in this way to prevent skin damage

• ground substance − a gel-like substance that helps to support the cells within the dermis and provides structure to the area

The hypodermis

The hypodermis provides support for the dermis and is made up largely of fatty and connective tissue. It is essential for protection of internal structures and also provides insulation.

Be Healthy Be Happy !

Dermatologist : The structure and function of the skin ( Complete Guide ) 2018-12-20T19:00:00-08:00 Rating: 4.5 Diposkan Oleh: David Maharoni