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Anatomy & Phsyiology
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Chapter 6

Skin & It's Tissues

General Characteristics
a. protective covering
b. regulate body temperature
c. houses sensory receptors
d. synthesizes chemicals
e. excretes wastes
f. composed of dermis and epidermis

Epidermis
- stratified squamos, lacks blood supply
- Stratum basale ~ deepest layer: mitotic cells
- Kereatinization ~ hardening of epithelial cells being pushed to the surface
- Stratum corneum - the outer most level, dead cells
- production of epithelial cells equal to loss ofcells at the surface
- protects against: water loss, mechanical injury, effects of harmful chemicals
- melanin ~ pigment within the cell protects against UV light
- melanocytes transfer melanin to nearby epidermal cells

Dermis
- composed of irregular dense connective tissue that binds the epidermis to underlying tissue
- also containing muscle cells, blood vessels, and nerve cell processes
- dermal blood vessels supply nutrients to skin cells and in regulating body temperature
- nervous tissue is scattered throughout the dermis
~ some dermal nerve cell processes carry impulses to muscles and gland of the skin
~ other dermal nerve cell processes are associated with sensory receptors in the skin

Subcutaneous Layer

- composed of loose connective tissue and adipose tissue
- adipose insulate (hold heat)
- contains blood vessels that supply the skin

ACCESSORY ORGANS OF THE SKIN

Hair follicles
- occurs in nearly all regions of the skin
- each hair develops from epidermal cells at the base of a tubelike hair follicle
- same process of kertinization undergone
- grows, rests, and then is replaced (stages of hair growth)
- hair color ~ determined by genetics
- each hair follicle is associated with a few muscle cells, and sebaceous gland

Nails
- protective covers on the ends of fingers and toes
- produced by epidermal cells that undergo Keratinization

Skin Glands
- sebaceous glands secrete sebum ~ helps keep skin and hair soft and waterproof
- sebaceous glands associated with hair follicles
- sweat glands are located in nearly all regions of the skin
- sweat gland consists of a coiled tube
- ecrine sweat glands respond to elevated body temperature or emotional stress (located on the forehead, neck,back,palms, and soles)



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