ch 5 Flashcards
function of the integumentary system
thermoregulation: contribute to body temp regulation; adjusting blood flow to the dermis
blood reservoir: holds large volumes of blood
protection: keratin:protects underlying tissues from microbes, abrasion, heat and chemicals. lipids: inhibit evaporation. sebum: keeps hair and nails from dying out, contains bactericidal chemicals. Acid PH: retards growth of some microbes. melanin: uv protection. intraepidermal macrophages: phagocytizes microbes.
cutaneous sensation: detection of touch and pressure, vibration and tickling, pain
excretion and absorption: excretion of salts, water and organic wastes.
synthesis of vitamin d.
2 major components of integument
- Cutaneous membrane
- – epidermis: superficial epithelium; avascular and composed of epithelial tissue
- – dermis: underlying area of connective tissue: vascular and composed of connective tissue - Accessory structures: hair, nails, exocrine glands (sebaceous glands- sebum, oil; ceruminous glands- cerumen wax; sudoriferous glands- perspiration sweat- merocrine and apocrine)
skin layers; Come Lets Get Sun Burned
- Stratum Basale: deepest layer
- Stratum Spinosum
- Stratum Granulosum
- Stratum Lucidum (only in thick skin)
- Stratum Corneum: superficial layer
Stratum Basale
deepest epidermal layer; in contact with basement membrane and attached by hemidesomosomes.
composed of single row of cuboidal or columnar keratinocytes wich have scattered tonofilaments. Also contains dividing cells called basale(germinative) cells
1. merkel cells (tactile cells): respond to light touch and superficial pressure; works with merkel discs (tactile discs)
2. melanocytes: produces pigment melanin (pheomelanin: yellow brown; Eumelanin: brown-black)
stratum spinosum
spiny layer; provides strength and flexibility to skin. keratinocytes produce coarser bundles of keratin intermediates, cells shrink appearing spiny. Lamellar bodies (granules) accumulate.
—dendritic (langerhans) cells: active in immune response. move around epidermis looking to engulf anything harmful
Stratum Granulosum
the grainy layer. Marks transition between deeper, matabolically active strata and the dead cell layers of more superficial strata. keratinocytes stop producing keratin. keratohyalin: dense granules, cross-link keratin fibers, promotes further dehydration. membrane enclosed lamellar bodies release lipid rich secretion, hard protein envelope forms beneath plasma membrane
stratum lucidum
clear layer. found only in thick skin 4-6 layers. cells are clear, flattened, dead, densely packed together, largely devoid of organelles, filled with keratin and thickened plasma membrane
stratum corneum
horny or cornified layer. exposed surface of skin. resistant to abrasion, repels water, protects again microbes
4 cell types in the epidermis
A. keratinocyte: keratin intermediate.
B. melanocyte (pigment) : melanin granule
C. intaepidermal macrophage cell
D. tactile epithelial (merkel) cells/ tactile (merkel) disc: light touch and pressure.
skin coloration
epidermal pigmentation:
- carotene: an orange-yellow pigment that normally accumulates in epidermal cells, fatty tissues in the deep dermis and subcutaneous layer. Can be converted to Vitamin A.
- Melanin: brown, yellow- brown or black pigment produced by melanocytes. Transfer of melanin contaning intracellular vesicles called melanosomes from melanocyte to keratinocyte. Protects cutaneous membrane from harmful effects of UV radiation. melanin synthesis accelerates slowly.
Dermis
tissue layer that supports the epidermis. Anchors epidermal accessory structures. Contains all the cells of connective tissue proper, networks of blood vessels and nerve fibers.
Dermis: Papillary Layer
superficial layer (20%) consists of areolar tissue, contains smaller capillaries, lymphatics, and sensory neurons. has dermal papillae projecting between epidermal ridges. contain fibroblast
Dermis: Reticular layer
deeper, thicker layer (80%) consists of dense irregular collagenous connective tissue. contains larger blood vessels, lymphatic vessels, nerve fibers, hair follicles, sebaceous and sudoriferous glands
Thin skin
hairy skin except for lips and external genitalia
makes up majority of superficial epithelium
composed of 4 layers
dermis is thicker than thick skin
contain hair, sebaceous gland, merocrine (eccrine) sweat glands, some areas have apocrine sweat glands.
Thick skin
hairless skin
found in fingertips, toes, soles of the feet and palms of hands.
composed of 5 strata
dermis is thinner than thin skin
does not contain hair, sebaceous gland or apocrine sweat, but contains merocrine (eccrine) sweat glands