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Published byJasper Peters Modified over 6 years ago
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Structure of the Skin Divided into 3 basic layers: 1. Epidermis
3. Subcutaneous tissue
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Epidermis: top level Made up of 5 cell layers (from bottom to top):
Basal (deep) Spinus Granular Lucidum Corneum (superficial)
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Basal cell layer Deepest layer
Cells are continually dividing to produce new skin cells (millions daily) These cells move towards the skin surface, Blood is provided by the dermis below
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Spinus cell layer Cells above the basal cell layer become more irregular in shape
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Granular cell layer Cells are moving away from the blood supply, the cells begin to flatten and die Keratin begins to form in the cells.
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Lucidum cell layer Clear-ish layer of skin
Only found where the skin is hairless and extra thick lots keratin to provide water-repellent properties
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Stratum Corneum Layer of skin we SEE
Made up of overlapping squamous cells Cells are dead and constantly shedding These cells provide the tough and watertight function of skin
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Dermis layer “hide” Contain many of the structures that are found within our skin. Arteries and veins run through this layer
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Structures of the Dermis
Cutaneous glands Sebaceous gland Sweat glands Hair Nails Nerves Collagen and elastin fibers
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Cutaneous Glands All exocrine glands that release their secretions to the skin surface via ducts 2 groups: Sebaceous glands Sweat glands
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Sebaceous Glands Glands that secrete sebum (oil)
Ducts empty out into hair follicles
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Characteristics of Sebum
Lubricant that keeps skin soft and moist Prevents hair from becoming brittle Chemicals that kill bacteria The gland becomes highly active during adolescence
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Acne Sebaceous gland’s duct becomes blocked by sebum
A whitehead forms on skin surface. If the material oxidized and dries, it darkens and becomes a blackhead
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Sweat Glands More than 2.5 million per person 2 types:
Eccrine: found all over the body Apocrine: found only in genital and axillary regions
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Sweat Made up of water, NaCl, vitamin C, metabolic wastes, and lactic acid Ducts that lead to the surface of the skin are called pores
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Sweat Gland and Pore
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Homeostatic Uses of Sweat
Supplied with nerve endings that cause them to secrete sweat when outside or body temperature is too high
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Hair Earlier humans had more hair for insulation and self defense
Current uses for hair: Guarding head against minor impact Shielding the eyes Keeping particles out of respiratory organs
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Structure of the hair Root: enclosed in the follicle
Shaft: projecting out of the scalp Hair bulb matrix: Inferior end of the follicle. Where new hair is formed.
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Hair Follicles Where hair forms and attaches to the body
Made of 2 layers: Inner epidermal layer: forms the hair Outer dermal sheath: supplies blood and reinforces hair to body
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Arrector pili Small bands of smooth muscle cells
When contracted the hair is pulled upright, dimpling the skin surface “goosebumps”
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Nails Made up of keratinized skin cells
Scale-like modification of the epidermis that corresponds to the hoof or claw of other animals
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Subcutaneous layer The innermost layer of the skin Composed of fat
thickness varies upon body region This layer performs 2 major functions: energy source for the body helps to insulate the body against temperature.
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