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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)

Epidermis

Keratinized stratified squamous epithelium

Keratinocytes

Produce fibrous protein keratin

Melanocytes

10 to 25% of cells in lower epidermis; Produce pigment melanin

Epidermal Dendritic (Langerhans) Cells

Macrophages that help activate immune system

Tactile (Merkel) Cells

Touch receptors

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

Stratum Granulosum

3 - 5 layers of flattened cells, organelles deteriorating; cytoplasm full of lamellated granules (release lipids) keratohyaline granules

Stratum Spinosum

Several layers of keratinocytes unified by desmosomes; cells contain thick bundles of intermediate filaments made of pre-keratin

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

Dermis

Strong, flexible connective tissue; Cells include fibroblasts; macrophages, and occasionally mast cells and white blood cells; Papillary and Reticular layer

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

Reticular Layer of Dermis

80% thickness of dermis; Collagen fibers provide strength and resiliency; Elastic fibers provide stretch-recoil properties

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

Carotene

Yellow to orange pigment, most obvious in palms and soles

Hemoglovin

Responsible for pinkish hue of skin

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

Apocrine Sweat Glands

Axillary and anogenital areas; Sebum (sweat and fatty substances/proteins; Ducts connect to hair follicles; Functional from puberty onward

Specialized Apocrine Glands

Ceruminous glands in external ear canal - secrete cerumen; Mammary glands

Sebaceous (Oil) Glands

Widely distributed; Most develop from hair follicles; Become active at puberty

Sebum

Oily holocrine secretion; Bactericidal; Softens hair and skin

Hair Functions

Tactile function; Guards scalp against physical trauma, heat loss, sunlight

Hair Distribution

Entire surface except palms, soles, lips, nipples, portions of external genitalia

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

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

Hair Follicle Receptor

Root hair plexus; Sensory nerve endings around each hair bulb, stimulated by bending a hair

Arrector Pili Muscle

Smooth muscle attached to follicle; Responsible for "goose bumps"

Structure of Nail

Scalelike modification of epidermis on distal and dorsal surface of fingers and toes

Biological Barriers

Epidermal dendritic cells and macrophages; Low pH secretions (acid mantle) and defensins retard bacterial activity

Physical/Mechanical Barriers

Glycolipids block most water loss; Limited penetration of skin by lipid-soluble substances, plant oleoresins, organic solvents, heavy metals, some drugs,

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

Metabolic Functions

Synthesis of vitamin D precursor

Cutaneous Sensations

Temperature, touch, and pain

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

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

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

Melanoma

Most dangerous form of skin cancer; Involves melanocytes; Highly metastatic and resistant to chemotherapy; Treated by wide surgical excision accompanied by immunotherapy