Integumentary System Flashcards
components
cutaneous membrane- skin
accessory structures
epidermis- epithelial tissue (keratinised stratified squamous)
dermis-
papillary
reticular- dense connective tissue
hypodermis- loose connective tissue
functions
protection, excretion, sensation- touch, pain, pressure, temp, maintenance of body temp, production of melanin and keratin, synthesis of vit. D
structure of epidermis
top down
surface- dead cells are shed
stratum corneum- dead, flat keratinocytes which lose organelles
stratum lucidim- flattened clear cells, layer only present in thick skin (dead)
stratum granulosum- grains of keratin produced, cells start apoptosis (cell death)
stratum spinosum- keratinocytes shrink and dehydrate
stratum basale- basal keratinocytes divide
basement membrane
dermis
EGF- epidermal growth factor
process of division and regeneration controlled by EGF
stimulates cell division, keratin production and glandular secretion, accelerates tissue repair
thick skin
renounced ridges (stratum lucidum)
fingertips, palms, soles
thickness- 0.6-5.4mm
strata- thick strata lucidum, spinsoum and corneum
ridges are present due to developed dermil papillae
hair follicles absent
sweat glands more numerous
more sensory receptors
thin skin
rest of the body
0.10-0.15mm
no strata lucidum, thinner strata spinosum + corneum
ridges are absent
hair follicles present
sweat glands fewer
less sensory receptors
melanocytes
secrete melanin (produced from amino acid tyrosine) - give skin pigment
melanin- brown, contributes to freckles and tan
protects us from UV + burning
increase in conc during sun exposure
skin pigment + colouration
carotene- yellowish
blood- contributes to pink or blue colouration
dermis
layer that is deep to the epidermis
supports epidermis- with collagen and elastin fibres
papillary layer- superficial layer- form ridges on thick skin (loose connective tissue- areolar)
reticular- deeper layer- dense connective tissue (fibrous network)
blood vessels- papillary plexus - supply epidermis
cutaneous plexus
sensory receptors- touch, pressure, pain receptors
hypodermis
layer underneath dermis
loose connective tissue (areolar and adipose tissue)
fewer collagen fibres
adipose tissue may be stored here
connective tissue fibres interwoven with reticular layer of dermis- not attached to basement membrane
cutaneous membrane
adipose tissue
areolar- loose connective tissue
hair follicles and hair
functions- protection, insulation, sensation
in dermis- sebaceous gland (produces oil + secretes onto shaft)
hair structure
medulla core- contains flexible soft keratin
cortex- dead keratinocytes layers of thick hard keratin, providing stiffness
cuticle- thin but tough
hair growth
basal cells in hair matrix divide, daughter cells pushed towards surface, become increasingly keratinised
end of cycle- cells of hair matrix stop dividing, connections between hair matrix and root break down + hair falls out
new growth cycle begins, new hair produced and old hair shed
subaceous gland
secrete sebum
oils produced in bottom ares, cells break down, oil is secreted onto hair shaft + to the skin
basal cells grow and break down cell membranes
nails
protect end of fingers + toes, limit distortion
nail root- where growth occurds
sweat glands
coiled structure in dermis, in duct which feeds onto shaft of hair
apocrine- found in armpits + pubic region, secrete thick odorous fluid
merocrine- produced all over body, secrete watery fluid + involved in thermoregualtion
sweat function
skin surface cooling
secretion of waste products eg urea + lactate
protection via secretion of antibodies
skin cancer
uncontrolled cell replication
78% basal cell carcinomas
2% malignant melanoma
1st degree burn
affects epidermis, makes skin look pink/ red
inflammation which increases blood flow
stimulates increased growth of skin- flaking
eg sun burn
2nd degree burn
involves damage to dermis
blisters/ scars may form
3rd degree
extends to hypodermis
destroys sensory nerves in epidermis (so less painful)
dangerous as may disrupt fluid and electrolyte balance which protects from infection
repair of injury
1- bleeding occurs, mast cells trigger inflammatory response
2-clot (scab) forms with fibrin network
phagocyte cells collect at bottom of clot, stratum basale migrates around edges
3- mesh produced by fibroblasts underlying wound, scab undermined by epidermal cells
4- epidermis complete, shallow depression, scar tissue around wound
skin aging
intrinsic- reduction in cell activity, growth factors, immune sensitivity
leads to- white hair, increased infection risk
extrinsic- sunshine exposure, smoking
leads to- increased wrinkling, skin cancer risk
