integumentary system Flashcards
5 integumentary system functions
protection, body temp regulation, excretion, vitamin D production, sensory reception
protection
cushions and insulates deeper structures
body temperature regulation
capillary network and sweat glands control heat loss
excretion
salts, water, and urea through sweat
vitamin D production
epidermal cells utilize UV radiation to synthesize vitamin D
sensory reception
touch, pressure, temperature, and pain
regions of skin
epidermis, dermis, hypodermis
keratinocytes
present in every layer of epidermis, dead keratin producing cells, spiny layer with the most abundant epidermal cells, produce keratin
keratin
fibrous protein that provides mechanical protection, produces antibiotics and enzymes that detoxify chemicals
melanocytes
basal layer, manufacture and secrete the pigment melanin (skin color)
tactile epithelial cells
basal layer, attached to sensory nerve endings, interpretation of innervation (sense, touch, taste)
dendritic cells
spiny layer, part of immune system, star shaped cells, migrate in and invade microorganisms
where skin is thick (palms and soles)
5 layers of epidermis
where skin is thin (remainder of body)
4 layers of epidermis
layers of epidermis
stratum basale, stratum spinosum, stratum granulosum, stratum lucidum, stratum corneum
stratum basale
deepest layer, attached to underlying dermis, cells actively divide, contains tactile epithelial cells and melanocytes
stratum spinosum
contains thick bundles of intermediate filaments that resist tension, contain dendritic dells, fibers stick to deeper layers holding it together
stratum granulosum
allows us to have waterproof skin, thin layer that consists of flattened keratinocytes along with keratohyalin granules (help from keratin) and lamellate granules )(waterproofing glycolipid, slows water loss)
stratum lucidum
only in thick skin, several rows of dead keratinocytes
stratum corneum
closest to outside body, thick layer of dead keratinocytes & thickened plasma membranes, protects skin, cells shed constantly (dandruff / dry skin flakes)
what happens during sunburn?
you are burning layers of active cells ruining DNA, can lead to cancer
dermis
strong, flexible connective tissue, richly supplied with blood vessels & nerves, 2nd major layer of skin
2 layers of dermis
papillary layer, reticular layer
papillary layer
outermost layer, nipple like projections stick up into epidermis and hold epidermis to dermis
reticular layer
strength, durability, a little bit of stretch
epidermal ridges
on palms & soles creating fingerprints, palm prints, and footprints from dermal ridges elevating the overlying epidermis
tension (cleavage) lines
allows skin to crease during movement, cutting along a cleavage line and sewing ends back together scar does not form, cut across a cleavage line, lines will never merge back together
hypodermis
part of body insulating to prevent heat loss, anchors skin to underlying structures (mostly muscles) while allowing sliding
what kind of connective tissue does hypodermis contain?
areolar and adipose
three pigments that contribute to skin color
melanin, carotene, hemoglobin
melanin
made from tyrosine, skin color variation due to difference in the type and amount of melanin produced
carotene
yellowish pigment obtained from carrots and tomatoes, absorbed easily into skin, found in every self tanner
hemoglobin
allows crimson color of blood in dermal capillaries to show through (redness on cheeks is the blood vessels from epidermis to dermis)
nails
scale-like modifications of epidermis made of hard keratin (dead keratin), root of nail is the only living part
hair
flexible strands of dead keratinized cells, root embedded in skin, shaft projects above skin surface
3 concentric layers of keratinized cells
medulla (central core), cortex (surrounds the medulla), cuticle (outer most layer)
hair follicles
extend from epidermis into dermis
hair bulb
deep, expanded end of the hair follicle
root plexus
knot of sensory nerves around the hair bulb (touch reception)
arrector pili
bundles of smooth muscle- hair stands erect when arrector pili contracts
sebaceous glands
occur over the entire body, except on the palms and soles, secrete sebum
sebaceous glands
occur over the entire body except for palms and soles, secrete sebum
sebum
an oily substance that collects dirt, softens & lubricates hair and skin (causes body odor)
sudoriferous glands
widely distributed on surface of body, only in mammals, sweat glands
sweat
a blood filtrate, 99% water with some salts and traces of metabolic wastes
2 types of sweat glands
eccrine glands, apocrine glands
eccrine glands
more numerous, produce true sweat (watery, salts, electrolytes)
apocrine glands
axillary, anal, and genital areas, contain fatty substances and proteins (source of body odor)
modified sweat glands
in lining of external ear canal (produce waxy secretions) and mammary glands
