Module 4: Skin Physiology - Structure Of The Skin

STRUCTURE OF THE SKIN:

The skin is made up of several layers that are illustrated in the slide below.

An upper stratum corneum overlies the epidermis (A) that interfaces with the dermis (C) and subcutaneous tissue (G).

Adenexal structures include the glands of the skin and the hair follicles. The eccrine glands (D) produce eccrine sweat which is excreted onto the surface of the skin. They are composed of a secretary coil and duct and have controls and functions comparable to the renal glomerulus and tubule. The clear secretions contain NaCl, ammonia, amino acids, proteins, urea and lactic acid. The latter two components contribute to barrier function, as they are the humectants responsible for retaining water in the stratum corneum.

The apocrine glands (not show on this diagram) only become functional at puberty. They are also composed of a secretary coil and duct but their secretions are discharged into the hair follicle. The secretions are milky and odour producing.

The sebum, containing lipids, proteins and the humectant glycerol, produced by the sebaceous gland (F) with its associated hair follicle (E) contributes to the skin barrier function.

The subcutaneous tissue and dermis are supplied with a rich network of blood vessels and functional vascular shunts (H) which allow for the diversion of blood to and from the skin as needed for temperature and haemodynamic homeostasis. A rich cutaneous nerve supply, not shown on the slide, is also integral to skin function.

The epidermis will be discussed in more detail in the next frame.