Brief overview of the skin's functions

The human skin is the largest organ of the human body and plays several vital roles including, protection, sensation, temperature regulation and communication. In addition, it is also capable of healing itself.

I have discussed the anatomy and physiology of the skin in previous articles and will therefore focus on pores and their associated glands of the skin in this article.

There are literally millions of pores covering the surface of our skin and these pores play a very important role in the overall function of the skin and the health of our bodies. Often these skin pores are referred to a sweat glands, however they are more than that.

The microscopic anatomy of skin reflects this functional complexity, with each functional specialization implemented by particular features of cell and tissue structure.

Structurally the skin is basically divided into two layers, the epidermis (outer skin) and the dermis (skin below the surface). The epidermis is the epithelial tissue layer of the skin and contains hair follicles, sebaceous glands, and sweat glands, which originate in the dermis and protrude to the surface of the skin (the epidermis).

Focusing on the pores of the skin, lets look at the Sweat Glands first.

These glands are tubular and their secretory portion originates deep in the dermis. Secretions from these glands reach the skin's surface via a duct that passes through the dermis and epidermis to the outermost layer of the skin.

The secretory portion of sweat glands is comprised of larger cells than the duct. These cells form a simple cuboidal epithelium, along with interspersed myoepithelial cells, which can expel sweat by contraction.

Cells lining the duct re-absorb certain elements from the fluid, secreted by the secretory portion of the sweat gland, as the fluid passes through the duct. This is primarily to conserve salt.

Sweat glands play a primary role in the body's temperature regulation by means of a process called evaporative cooling.

There are two types of sweat glands, ordinary eccrine sweat glands found over most of the body and large apocrine sweat glands found in axillary, pubic, and perianal regions.

Sebaceous Glands

Sebaceous glands are part of the pilosebaceous apparatus, which consists of the sebaceous gland, the hair follicle and the hair shaft.

Unlike all other glands, sebaceous glands are holocrine glands, which means they secrete whole cells. The secreted cells are dead by the time they reach the surface of the skin but whilst alive and on their way to the surface, they absorb lipids (triglycerides and free fatty acids, wax esters, squalene, and cholesterol) which are then secreted to the skin's surface via the lumen (opening/pore) of the hair shaft. The secretion of sebaceous glands is referred to as sebum.

Whilst most of the sebaceous glands are indeed associated with the pilosebaceous apparatus some glands open directly to the surface of the skin such, for example the Meibomian glands of the eyelids.

Sebum secretion is under hormonal control and sebaceous gland development occurs during puberty. Blockage, or excessive build up of sebum can lead to acne which is of primary concern to many teenagers and can reoccur during mid-life as 'adult acne'.

As mentioned earlier, sebum is composed of triglycerides and free fatty acids, wax esters, squalene, and cholesterol. The secretion of sebum performs several functions. Firstly, the water-holding power of cornified epithelium depends on the presence of these lipids and secondly, sebum protects the skin against fungal and bacterial infections. This is sometimes referred to as the 'Acid Mantel' of the skin.

As you can see, the secretions from the pores of the skin are in fact much more than mere sweat and serve some very important functions. The 'Acid Mantel' for example is a key immune defence of the body protecting the inside from the external environment and thus reducing the chance of infection.

Danny Siegenthaler is a doctor of traditional Chinese medicine and together with his wife Susan, a medical herbalist and Aromatherapist, they have created Natural Skin Care Products by Wildcrafted Herbal Products to share their 40 years of combined expertise with you.

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