Dermis

Skin 4, Dermis

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• published: 30 May 2013
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If you would like to get hold of my books, one on Physiology and another on Pathophysiology, check out my web site campbellteaching.co.uk Funds from selling books helps to finance distribution of resources to students in poorer countries. Hair has a characteristic sexual distribution in humans varying between males and females. The purpose of hair on the head is probably to protect the head and the body against direct sunlight. Hair also increases the sensitivity of the skin to touch. There is also some social aesthetic function, especially in females. Hair follicles house the hairs and are fairly deep structures that go down into the dermis. The hair follicles are lined with an infolding of the epidermis. Sebaceous glands produce sebum and deposit this product in the hair follicles, this greasy substance helps keeps the skin supple and waterproof. Ceruminous glands produce cerumen which is a waxy substance, they are located in the skin of the external auditory meatus, (outer ear passage). Sweat glands produce sweat from plasma, sweat produced in a sweat gland rises to the surface of the epidermis in the sweat gland duct, depositing sweat on the body surface where it aids in cooling. Sensory receptors are found in the dermis and allow for tactile sensation to be experienced. There are four main types of peripheral sensory receptors each with a specialised function for the detection of pain, pressure, temperature and touch. There is a separate type of receptor for each sensation. There are a lot of capillary beds in the skin, these are supplied with blood from an arteriole and the blood is drained from capillary beds by a venule. It is the perfusion of these capillary beds with blood which give the skin its characteristic pink/rosy colour in white people. Fibroblasts found in the dermis produce collagen for strength and yellow elastic fibres for elasticity.