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37 Cards in this Set
- Front
- Back
Skin (Integument |
Consists of three major regions; Epidermis (superficial), Dermis (middle), Hypodermis (deep, mostly adipose tissue) |
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Epidermis |
Keratinized stratified squamous epithelium |
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Keratinocytes |
Produce fibrous protein keratin |
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Melanocytes |
10 to 25% of cells in lower epidermis; Produce pigment melanin |
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Epidermal Dendritic (Langerhans) Cells |
Macrophages that help activate immune system |
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Tactile (Merkel) Cells |
Touch receptors |
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Stratum Corneum (Horny Layer) |
Most superficial layer; 20 - 30 layers of dead, flat, keratinized membranous sacs; Three-quarters of epidermal thickness; Protects from abrasion/penetration; Waterproofs; Barrier against biological, chemical, and physical assaults |
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Stratum Granulosum |
3 - 5 layers of flattened cells, organelles deteriorating; cytoplasm full of lamellated granules (release lipids) keratohyaline granules |
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Stratum Spinosum |
Several layers of keratinocytes unified by desmosomes; cells contain thick bundles of intermediate filaments made of pre-keratin |
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Stratum Basale |
Deepest epidermal layer; one row of actively mitotic stem cells ; some newly formed cells become part of more superficial layers; occasional melanocytes and epidermal dendritic cells |
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Dermis |
Strong, flexible connective tissue; Cells include fibroblasts; macrophages, and occasionally mast cells and white blood cells; Papillary and Reticular layer |
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Papillary Layer of Dermis |
Areolar connective tissue with collagen and elastic fibers and blood vessels; Dermal papillae contain capillary loops, Meissner's corpuscles, and free nerve endings |
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Reticular Layer of Dermis |
80% thickness of dermis; Collagen fibers provide strength and resiliency; Elastic fibers provide stretch-recoil properties |
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Melanin |
Yellow to reddish brown to black, responsible for dark skin colors; Produced in melanocytes, migrates to keratinocytes where pigment shields form for nuclei; Freckles and pigmented moles are local accumulations of melanin |
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Carotene |
Yellow to orange pigment, most obvious in palms and soles |
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Hemoglovin |
Responsible for pinkish hue of skin |
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Eccrine Sweat Glands |
Abundant on palms, soles, and forehead; Sweat is 99% water, NaCl, Viatim C, Antibodies, dermoidin, metabolic wastes; Ducts connect to pores; Function in thermoregulation |
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Apocrine Sweat Glands |
Axillary and anogenital areas; Sebum (sweat and fatty substances/proteins; Ducts connect to hair follicles; Functional from puberty onward |
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Specialized Apocrine Glands |
Ceruminous glands in external ear canal - secrete cerumen; Mammary glands |
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Sebaceous (Oil) Glands |
Widely distributed; Most develop from hair follicles; Become active at puberty |
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Sebum |
Oily holocrine secretion; Bactericidal; Softens hair and skin |
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Hair Functions |
Tactile function; Guards scalp against physical trauma, heat loss, sunlight |
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Hair Distribution |
Entire surface except palms, soles, lips, nipples, portions of external genitalia |
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Hair |
Consists of dead keratinized cells; Contains hard keratin, more durable than soft keratin of skin; Hair pigments - gray/white hair - decreased melanin production, increased air bubbles in shaft |
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Hair Follicle |
Extends from the the epidermal surface into dermis; Two-layered wall, outer connective tissue root sheath, inner epithelial root sheath; Hair bulb, expanded deep end |
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Hair Follicle Receptor |
Root hair plexus; Sensory nerve endings around each hair bulb, stimulated by bending a hair |
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Arrector Pili Muscle |
Smooth muscle attached to follicle; Responsible for "goose bumps" |
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Structure of Nail |
Scalelike modification of epidermis on distal and dorsal surface of fingers and toes |
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Biological Barriers |
Epidermal dendritic cells and macrophages; Low pH secretions (acid mantle) and defensins retard bacterial activity |
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Physical/Mechanical Barriers |
Glycolipids block most water loss; Limited penetration of skin by lipid-soluble substances, plant oleoresins, organic solvents, heavy metals, some drugs, |
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Body Temperature Regulation |
500 ml/day of routine insensible perspiration (at normal body temperature); At elevated temperature dilation of dermal vessels and increased sweat gland activity cool the body |
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Metabolic Functions |
Synthesis of vitamin D precursor |
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Cutaneous Sensations |
Temperature, touch, and pain |
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Skin Cancer |
Most skin tumors are benign (don't metastisize); Risk factors are overexposure to UV radiation, frequent irritation of skin; Some skin lotions contain enzymes in liposomes that can fix damaged DNA |
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Basal Cell Carcinoma |
Least malignant, most common form of skin cancer; Stratum basale cells proliferate and slowly invade dermis and hypodermis; Cured by surgical excision in 99% of cases |
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Squamous Cell Carcinoma |
Second most common form of skin cancer; Involves keratinocytes of stratum spinosum; Most common on scalp, ears, lower lip, hands; Good prognosis if treated by radiation therapy or removed surgically |
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Melanoma |
Most dangerous form of skin cancer; Involves melanocytes; Highly metastatic and resistant to chemotherapy; Treated by wide surgical excision accompanied by immunotherapy |