Accessory Organs of the Skin PDF

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Accessory Organs of the Skin I.

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Products of the epidermis A. Hairs and har follicles B. Nails C. Sweat glands D. Sebaceous glands E. Ceruminous glands F. Mammary glands Hair A. Dead keratinized cells of hard keratin 1. More durable than soft keratin of skin B. Not in palms, soles, lips, nipples, portions of external genitalia C. Functions 1. Warn of insects on skin 2. Physical trauma 3. Heat loss 4. Sunlight D. Hair pigment 1. Melanin 2. Red hair contains iron pigments 3. Grey/white hair: decreases melanin production, increased air bubbles in shaft E. Types of hair and growth of hair 1. Vellus hair a) Pale, fine body hair of children and adult females 2. Terminal hair a) Coarse, long hair of eyebrows, scalp b) At puberty (1) Appear in axillary and pubic regions of both sexes (2) Face and neck of males 3. Nutrition and hormones affect hair growth 4. Average 2.25 mm growth per week 5. Lose 90 scalp hairs daily

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F. Hair thinning and baldness 1. Alopecia a) Hair thinning or loss in both sexes after 40 2. True (frank) baldness a) Genetically determined and sex influenced condition Hair follicles A. Extend from epidermal surface to dermis B. Two-layered wall - part dermis, part epidermis C. Hair bulb 1. Expanded deep end 2. Hair follicle receptor 3. Sensory nerve endings - touch receptors 4. Hair matrix D. Arrector pilli 1. Smooth muscle attached to the follicle 2. Responsible for goosebumps E. Hair papilla 1. Dermal tissue - blood supply Nails A. Scale like modifications of epidermis B. Protective cover for the distal, dorsal surface of fingers and toes C. Contain hard keratin (epidermis is soft) D. Pink due to rich bed of capillaries E. Changes in nail appearance is helpful in certain conditions 1. Respiratory issues -> Cyanosis 2. Thickened nails -> Fungal infection F. Nail anatomy 1. Nail matrix a) Region of new hair growth b) Not visible; located deep to proximal nail fold 2. Eponychium (cuticle) a) Proximal nail fold that projects onto the body of the nail 3. Hyponychium a) Lies beneath free edge of nail

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b) Area where dirt accumulates c) Secures free edge of nail plate at the fingertip Cutaneous glands A. Sudoriferous glands 1. Two types a) Eccrine (1) Most numerous and widely distributed (2) Abundant on palms, soles, and forehead (3) Simple, coiled. Tubular gland connects to pores (4) Function in thermoregulation (a) Regulated by the sympathetic nervous system (5) Consists of (a) 99% water, salts, vitamin C, antibodies, microbe - killing protein, metabolic wastes b) Apocrine (1) Found in groin, anal region, axilla and nipple regions (2) Larger than eccrine sweat glands (3) Ducts empty into hair follicles (4) Function as scent glands (sex pheromones) (a) Become active at puberty (b) Respond to stress and sexual stimulation (5) Consists of sweat and fatty substances and proteins (a) Viscous, milky and yellows (b) Odorless until bacterial interaction -> Body odor 2. Also known as sweat glands 3. All skin surfaces except nipples and part of external genitalia 4. About 3 million per person

5. Contain myoepithelial cells a) Contact upon nervous system stimulation to force sweat into ducts B. Sebaceous glands 1. Widely distributed a) Not in thick skin of palms and soles 2. Most develop from hair follicles and secrete into hair follicles 3. Relatively inactive until puberty a) Stimulated by hormones, especially androgens 4. Secrete sebum a) Bactericidal b) Soften hair and skin C. Ceruminous glands 1. Found only in the external ear canal 2. Produce cerumen 3. Cerumin + sebum + dead skin cells = ear wax 4. Ear wax helps prevents infection and keeps ear drum pliable and provides waterproofing 5. Deters insects from gaining access to the inner ear D. Mammary glands 1. A type of modified apocrine sweat gland 2. Produce a richer secretion 3. Channeled through ducts to a nipple for infant nutrition...