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Integument - Skin
Layers and Properties
Term | Description | Function |
---|---|---|
Stratum Corneum | 1. TOPMOST of EPIDERMIS - Stratified Squamous over Cuboidal epithelium | DEAD, dehydrated, "Keratinized" squamous cells, constantly shed |
Stratum Lucidum | 2. "clear" Squamous cells | only in palms, lips, and soles |
Stratum Granulosum | 3. "granular" cells | nuclei disintegrate - cells are dying |
Stratum Spinosum | 4. spiny cells interlocked by Protein filaments | multi-sided (puzzle piece) |
Stratum Germinativum | 5. DEEPEST of EPIDERMIS - "germinating", actively dividing Cuboidal cells | Melanocytes: form and distribute melanin pigment |
Dermis | thick CONNECTIVE tissue | contains Receptors, Hair Folicles, Sweat and Sebaceous Glands |
Papillary Layer | UPPERMOST of DERMIS - AREOLAR tissue containing blood capillaries and nerves | provides friction ridges (FINGER PRINTS) |
Reticular Layer | DEEPEST of DERMIS - DENSE IRREGULAR connective tissue made of Collagen and Elastin | provides STRENGTH and FLEXIBILITY |
Subcutaneous Layer (Hypodermis) | BENEATH DERMIS - Simple AREOLAR tissue and ATIPOSE | for FAT STORAGE and ATTACHMENT to underlying muscle tissue |
Nails | KARITINIZED PLATES of flat EPIDERMAL cells | Grasping, Manipulation, Protection |
Hair | KARITINIZED epithelial TUBES with a hollow core - pigmented cortex (melanin) determines hair color | follicle supplied with ARRECTOR PILI muscle - SENSATION and THERMAL insulation |
Sebaceous Glands | arise from the walls of HAIR FOLLICLES | product: SEBUM - regulated by: SEX HORMONES - coats/SEALS Hair and Epidermis |
Sweat (Sudoriferous) Glands | coiled epithelial tubes | product: SWEAT (water, NaCl and metabolic waste) - regulated by: TEMPERATURE and PSYCHOLOGICAL factors |
Thermoregulation | Heat Conservation or Loss at skins surface | TO regulate body TEMPERATURE |
Vasodilation | MORE blood flows | more HEAT LOST |
Vasoconstriction | less BLOOD FLOWS | to KEEP HEAT |
Absorption | Function of the Skin (uptake limited due to waxy SEBUM and KERITINIZATION) | some diffusion of GASES and FAT-soluble drugs |
Hydro-regulation | Function of the Skin | guards against WATER LOSS or GAIN |
Protection | Function of the Skin - 2 occlusive BARRIERS: Chemical Barrier: SEBUM, KERATIN, and MELANIN - Physical Barrier: Stratum CORNEUM and HAIR | Protection Against: BACTERIA, PARASITES, U.V. RADIATION, NOXIOUS CHEMICALS, and FRICTION |
Chemical Barrier | SEBUM, KERATIN, and MELANIN | PROTECTION |
Physical Barrier | Stratum CORNEUM and HAIR | PROTECTION |
Reception | Function of the Skin - Sensory NERVES and RECEPTORS in the DERMIS | PROTECTION: sensations of TOUCH, PRESSURE, and PAIN |
Synthesis | synthesizes Vitamin D | helps absorb CALCIUM |