Appendages+of+the+Skin

Sweat glands are also called sudoriferous glands (sudor = sweat) They are distributed over the entire skin surface there are 2 types: Eccrine sweat glands Apocrine sweat glands There are two other specialised sweat glands I will mention: Mammary glands – produce milk Ceruminous glands – modified apocrine gland in the ear and produce ear wax – deter insects and other foreign material
 * Sweat Glands **
 * These are the most numerous
 * Their ducts open onto the skin
 * Secrete sweat which is approximately 99% H2O
 * Their function is in the control of temperature or thermoregulation
 * The secretion is regulated by sympathetic NS (e.g. cold sweat)
 * These are confined to the axilla (armpits) and anogenital region (bum)
 * Ducts empty into hair follicles
 * Secrete sweat + fats + proteins in sweat.
 * Bacteria eat the fat and the protein which results in the smell or your BO
 * Function note clear but it isn’t thermoregulation
 * Activated by puberty + testosterone, foreplay and they vary with menstrual cycle it is thought that perhaps they are actually sexual scent glands.

Sebaceous (oil) Glands (see * above): Found all over skin
 * // Other Glands: //**
 * Secrete sebum
 * Into hair follicle
 * Softens and lubricates skin/hair
 * Has bactericidal activity
 * Activated by androgens (hormones) @ puberty


 * Hair **

__Structure__ In cross section consists of a core called the medulla, a cortex, and an outermost cuticle __Types__ __Functions__
 * Filamentous strands of dead keratinized cells produced by hair follicles
 * Contains hard keratin which is tougher and more durable than soft keratin of the skin
 * Made up of the shaft projecting from the skin, and the root embedded in the skin
 * Pigmented by melanocytes at the base of the hair. Different combination of the melanin types to create hair colour range
 * Medulla: large cells and air spaces – absent in fine hair
 * Cortex: fat layer of flat cells
 * Cuticle: single layer of cells overlap like shingles – keeps hair away from each other so doesn’t mat
 * Vellus – pale, fine body hair found in children and the adult female
 * Terminal – coarse, long hair of eyebrows, scalp, axillary, and pubic regions
 * Helping to maintain warmth
 * Alerting the body to presence of insects on the skin
 * Guarding the scalp against physical trauma, heat loss, and sunlight
 * Distributed over the entire skin surface except
 * Palms, soles, and lips
 * Nipples and portions of the external genitalia


 * Hair Follicle **
 * Root sheath extending from the epidermal surface into the dermis
 * Deep end is expanded forming a hair bulb
 * A knot of sensory nerve endings (a root hair plexus) wraps around each hair bulb
 * Bending a hair stimulates these endings, hence our hairs act as sensitive touch receptors
 * Arrector pili muscle – associated with each follicle (see in picture above) . Smooth muscle that when it contract the hair rises and the skin dimples to cause goose bumps in response to cold external environment of fear (more important in other animals – hair sticks out to look scary)


 * Nails **
 * Scalelike modification of the epidermis on the distal, dorsal surface of fingers and toes
 * Plates of tightly packed, hard, keratinized epidermal cells[[image:ucanaandp/Fingernail_label.jpg width="284" height="158" align="right"]]
 * Consist of -
 * Nail body, free edge and nail root
 * Lunula
 * Hyponychium (nail bed)
 * Eponychium (cuticle)
 * Nail matrix
 * Epithelium deep to nail root
 * Cells divide by mitosis
 * Superficial cells of matrix converted to nail cells
 * Average growth 1 mm per week

Most skin tumors are benign and do not metastasize A crucial risk factor for nonmelanoma skin cancers is the disabling of the //p53// gene Newly developed skin lotions can fix damaged DNA

Structure and Cells of Skin Ageing and Homeostatic Imbalances Home