Integument (7) Flashcards
integument
contents
skin
sweat glands
sebaceous glands
hair
nails
functions of skin
- protect from microorganisms/dehyrdation
- reg of body temp by sweat
- reception by sensory nerve endings
- absorption of UV to form vit D
- excretion by sebaceous/sweat glands
thin skin
covers most of body surface
has hair follicles + arrector pili musclse + sebaceous + sweat glands
thick skin
palm of hand and soles of feet
has sweat glands only
skin layers
- epidermis-superficial/epithelial
- dermis- deeper CT layer
epidermis is avascular
epidermis cells
in general: stratified squamous keratinized avascular
keratinocytes-most common
nonkeratinocytes
keratinocytes
epithelial cells
provide physical barrier/is protective
continuous skin renewal by mitotic activity at night @ basal layer cells»accumulate keratin filaments as migrate to surface
evolve and desquamate every 25-30 days
nonkeratinocytes
langerhans cells
merkel cells
melanocytes
langerhans cells
from precurosrs in bone marrow > blood stream> epidermis mainly @stratum spinosum and superficial dermis
defensive cells
have cytoplasmic processes and Birbeck granules (tennis racket)
langerhan cell function
attach to antigens entering skin > travel to lymph node to interact w/ lymphocytes
merkel cells
@ base of hair follicles and fingertips
@stratum basale of epidermis
mechanoreceptors to enhance sensory perception
melanocytes
@stratum basale and superficial dermis
-from neural crest
syn melanin (protect skin DNA from UV radiation)
melanin pathway
- RER syn tyrosinase (enzyme)
- golgi packs it into melanosomes
- tyrosinase activated by UV light
- tyrosine > melanin via tyrosinase @melanosomes
- melanosomes released into ECS of spinosum > phagocytosed by keratinocytes
- move to supranuclear region to protect chromosomes from UV
differences in skin pigmentation
- tyrosinase activity
- # of melanin granules
- size of granules
- granule distribution
- rate of melanin breakdown
vitiligo
loss of pigment so white patches
due to dec or complete loss of melanocytes
autoimmunity or self destruction of melanocytes
albinism
melanocytes present but not syn melanin due to defect or absence of tyrosinase
malignant melanoma
causes: hereditary, light skin, xs sunlight exposure
ABCDE of melanoma
strata of thick skin
- corneum (superficial)
- lucidum
- granulosum
- spinosumm
- basale (deep)
can lucy get a spin bike
stratum basale
thick skin
columnar shape w/ desmosomes, rests on basement membrane w/ hemidesmos
most intense mitotic activity so layer of cell renewal
melanocytes and merkel cells reside
basal cell carcinoma
pearly papule
slow growing and rarely metastasize so treatable via surgery
stratum spinosum
thick skin
interdigitating processes/intercellular bridges held by desmosomes to keep cells from sep so bind and protect
spiny appearance/zipper/prickley
bundles of intermed filaments, langerhans cells, membrane coated granuels
IFs= tonofilaments + cytokeratin
stratum granulosum
keratohyalin granules (soft keratin protein) + membrane coating granules (lamellar bodies lipids)
waterproofs skin surface via exocytosis of lipid rich substance form sheet
lamellar bodies contents
- glycosphingolipids
- phospholipid
- ceramide
stratum lucidum
subdivision of stratum corneum w/ keratin filaments
NO organelles/nuclei aka non-viable cells
protective
stratum corneum
thick layer w/ keratin filaments + amorphous matrix (will thicken w/ friction aka callus)
flat/desiccated/keratinized dead cells so no nuclei or organelles
protective
desquamates easily bc no desmos b/t cells to bind
strata of thin skin
- thin corneum
- discontinous lucidum
- discontinuous granulosum
- thin spinosum
- stratum basale
ichthyosis
hyperkeratosis = fish scales presentation
papillary layer
dermis
superficial loose CT layer of dermis for defense
dermal papillae interdigitate w/ epidermal ridges (more prominent in high mechanical stress aka palms and soles)
papillary layer contents
dermis
LCT cells= fibroblasts, macrophages, plasma cells, mast cells
+reticular fibers
+elastic fibers
+Meissner corpuscles= mechanoreception
+abundant capillary loops for nutrition and thermoreg
reticular layer
dermis
dense irregular coll CT reticular layer for tensile strength w/ collagen bundles
thick elastic fibers for stretch/resilence
reticular layer contents
dermis
proteoglycans (rich in dermatan sulfate)
+fibroblasts, mast cells, lymphocytes, macrophages, fat cells
+hair follicles, arrector pili muscles, sebaceous glands, sweat glands
+pacinian corpuscles to detect deep pressure/vibrations
hypodermis
superficial fascia
not a part of skin
base/root of hair follicules
eccrine sweat glands
ordinary sweat glands, scattered thru skin/body
expel waste via merocrine secretion
-have myoepithelial cells to assist
-inn by postganglionic sympathetic fibers
simple coiled tubular shape
apocrine sweat glands
@ axilla, areola of nipple, anal region
merocine excretion, influenced by hormones and sympathetics
don’t start until puberty
sebaceous glands
syn sebum (natural cold cream) to soften skin
-influenced by hormones, active at puberty
holocrine secretion
hair follicle structure
1.bulb @ base (encloses dermal papilla)
2.cortex keratinized
2.medulla w/ mod keratinization
3.cuticle keratinized
4.internal root sheath w/ some keratiniz
5.glassy membrane
6.CT
external root sheath not a part of hair
dermis contents
- collagen (tensile strength)
- immune cells (defense)
- capillaries (nutrition/thermoreg)
- glands (thermoreg/excrete waste)
- nerve fiber terminals (sensation)
- elastic fibers (stretch)
arrector pili muscles
hair follicles
smooth muscle contract to raise hair follicles and conserve body heat
attaches to hair follicle midway/obliquely + cradles sebaceous gland
nail structure
- nail fold + eponychium
- root
- nail plate (dense keratinz) rest on nail bed (strat squamous)
- matrix (growth happens)
- hyponychium
