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A&P Integumentary
Integumentary System Chapter 6. Anatomy and Physiology MCB 244 UIUC
Term | Definition |
---|---|
epidermis | epithelium of the integument; keratinized stratified squamous epithelium |
Stratum Basale | (5)deepest epidermal layer; single layer of cuboidal to low columnar cells attached to an underlying basement membrane. Three cell types occupy: keratinocytes, melanocytes, Tactile cells |
Keratinocytes | most abundant cell type in the epidermis. Dominated by large keratinocyte stem cells. Synthesize keratin, a protein that strengthens the epidermis |
Melanocytes | long branching processes and are scattered among the keratinocytes. Produce and store the melanin pigment in response to UV light. Transfer in melanosomes to the keratinocytes in the basal layer. is near nucleus to prevent UV damage |
Tactile Cells | Merkel cells, sensitive to touch and when compressed release chemicals that stimulate sensory nerve endings, providing info about objects touching the skin |
Stratum Spinosum | (4)several layer of polygonal keratinocytes (spiny layer) once new cells enter the SS it begins to differentiate. Non-dividing keratinocytes attach to neighbors by desmosomes. Contains epidermal dendritic cells : immune cells , protect against pathogens |
Stratum Granulosum | (3) 3 to 5 layers of keratinocytes; cells undergo keratinization, cells begin to die |
Stratum Lacidum | (2)clear layer; thin translucent region of 2 to 3 cell layers. found onlt in thick skin within the palms of the hands and the soles of feet. Protect from UV light |
Stratum Corneum | (1) hornlike layer; most superficial layer; 20-30 layers of dead keratinized cells. Anucleate |
Thick skin | found on palm of hands and soles of feet. 5 layers in epidermal strata occur. Houses sweat gland but has no hair follicles or sebaceous glands. |
Thin skin | covers most of the body, lacks stratum lucidum, only 4 layers; contains hair follicles, sebaceous glands and sweat glands. |
skin color | combination of hemoglobin, melanin and carotene |
Melanin | pigment produced and stored in melanocytes. amount is determined by heredity and light exposure |
Carotene | yell orange pigment acquired from various vegetables; accumulates in keratinocytes of stratum corneum and subcutaneous fat |
Albinism | inherited recessive condition where enzyme needed to produce melanin is non functional. |
nevus | mole, harmless localized overgrowth of melanocytes. rare can become malignant from UV light exposure |
freckels | yellow brown spots that represent localized areas of increased melanocyte activity, not an increase of melanocyte numbers |
Hemangioma | anomaly that results in skin discoloration due to blood vessels that proliferate to form a benign tumor |
capillary hemangiomas | strawberry colored birthmarks appear as red to deep purple that are usually present at birth and disappear in childhood |
Cavernous hemangiomas | port wine stains involve larger dermal blood vessels and may last a lifetime |
friction ridges | fingers, palms, soles and toes. Ridges from large folds and valleys of dermis and epidermis; help increase friction |
Dermis | deep to epidermis, CT proper and collagen fibers; dendritic cells as immune function; blood vessels, sweat glands, sebaceous glands, hair follicles, nail roots, sensory nerve endings and arrector pili. papillary vs reticular |
Papillary layer of dermis | superficial region of dermis, areolar CT ; name from projections of dermis called dermal papillae; dermal papillae contain capillaries that supply nutrients and surface nerve endings |
Reticular layer of dermis | major portion of dermis, dense irregular CT, large bundles of collagen fibers project in all directions, "network" of collagen fibers |
Subcutaneous layer | not considered part of the integument; areolar CT and adipose CT; protects energy reservoir, provides thermal insulation |
Vitamin D3 | cholecalciferol; synthesized from a steroid precursor by keratinocytes when exposed to UV light. Increases absorption of Ca and phosphate from small intestine into blood, regulates levels in blood |
Functions of Integument | Protection, prevention of h2o loss and gain, metabolic regulation (d3), secretion and absorption, immune function, temp regulation, sensory reception |
Vasoconstriction | diameter of vessels narrow, less blood can travel through; net effect shunting of blood away from periphery and toward deeper structures, CONSERVING HEAT ; EXPOSURE TO COLD |
Vasodilation | diameter increases so more blood can travel through , excess heat can be lost is body is too warm , pink skin |
Hair | pilus, composed of keratinized cells growing from hair follicles that extend deep into demris |
Lanugo | fine, unpigmented downy hair that appears on the fetus in the last trimester |
Vellus | replaces lanugo, found on upper and lower limbs |
Terminal hair | coarser, pigmented and longer than vellus; grows on scalp, eyebrow hair and eyelashes; at puberty replaces vellus hair in the axillary and pubic regions and forms beard on faces |
Functions of Hair | protection; facial expression; heat retention, sensory reception, visual identification; chemical signal dispersal |
Hair color | result of melanin synthesis; aging decreases production of pigment |
Hair growth and replacement | Anagen, catagen, telogen |
Anagen Phase | acitve phase of growth where living cells of the hair bulb are rapidly growing, dividing and transforming into hair |
Catagen phase | brief regression period where cell division ceases and follicle undergoes involution |
Telogen phase | resting phase, hair is shed. After 3 to 4 months follicle reenter the anagen phase |
Alopecia | thinning of hair usually as a result of aging , both sexes |
Diffuse Hair lose | hair is shed from all parts of scalp. Women usually suffer due to hormones, drugs or iron deficiency |
Male pattern baldness | loss of hair first form crown region; caused by genetic and hormonal influences |
hirsutism | excessive male pattern hairiness in areas of the body that normally do not have terminal hair; growth on face, chest and back and can affect both sexes; commonly caused by excess of male sex hormones (androgens) through medical conditions or medications |
Fibrosis | too much damage; body fills gap with scar tissue (fibrous) replacement scar tissue is produced by fibroblasts and is composed of collagen fibers. Structural but not functional restoration |
Reneration | cut blood vessels bleed into wound, blood clot forms and leukocytes clean wound; blood vessels regrow and granulation tissue forms; epithelium regenerates and CT fibrosis occurs |