Integumetary system Flashcards
epidermis description
keratinised stratified squamous epithelial cells
has 4/5 layers
AVASCULAR
stratum basale
a row of cells continuously in mitosis (simple cuboidal)
contains tactile cells and melanocytes
forms a basement membrane
stratum spinosum structure
cells contain pre keratin filament, dendritic cells, and keratinocytes held together by desmosomes
stratum granulosum structure
3-5 more layers of keratinocytes
keratinisation begins - organelles degenerate, cytoplasms become granular due to released enzymes and lipids (that were originally inside organelles)
stratum lucidum
2-3 layers of dead cells, only found on thick skin like palms and feet to protect from abrasion
stratum corneum
20-30 cells thick, thicker in thick skin
aneucleate, filled with keratin
dermis description
connective tissue
vascular
contains nerves, blood vessels, lymphatic vessels
papillary layer
more superficial layer, areolar connective tissue (more loose) contains capillaries, sensory nerve endings
reticular layer
denser, irregular connective tissue made of collagen and elastin
contains blood vessels, hair follicles, sweat and sebaceous glands surrounding blood vessels
describe hypodermis structure and function
made up of fatty subcutaneous tissue for energy storage and insulation
anchors skin to bones and muscles
provides passages for blood vessels, nerves, lymphatic vessel
protects rest of body from harm
melanocytes
produce melanin, protects cell nuclei from UV light
everyone has the same amount of melanocytes, different types and ratios of melanin produced
eumelanin: brown black
pheomelanin: red yellow
other pigments in skin apart from melanin
carotene: orange-yellow, accumulates in palms and soles and is converted to vitamin A
haemoglobin: gives pale skin a pinkish-red tint
describe parts of hair follicle
hair follicle: the whole hair
hair shaft: part of hair that comes out of the skin
hair root: part of hair you can’t see, anchors hair to skin
hair bulb: attatched to papilla for blood supply
types of hair
vellus hair: found on the skin
Terminal hair: found on the scalp, axillary area, anogenital area, converted from vellus hair by androgens during puberty
no hair at palms, soles, lips
pili erector muscles
autonomous smooth muscles, contracts when cold
merocrine glands
exocrine glands that secrete sweat into duct and onto skin surface, no odour, used in thermoregulation
apocrine glands
cell surface breaks away and is excreted, simple cuboidal/columnar cells with a large lumen
secreting sweat that is slightly fatty
secreted into terminal hair follicles
odour due to bacteria
anogenital and axillary areas
holocrine glands
secrete whole cells into the hair follicles, sebaceous glands
sebocytes closest to duct will explode and release sebum into follicle
acinar (grape shaped), converge into 1 short duct like a sac
nails structure
hard plates of keratin
cuticle
nail bed
nail folds
lunula
7 functions of skin
absorption
protection
sense organ
thermoregulation
communication
vitamin production
excretion
absorption
lipid based creams and gases, transdermal drug delivery
protection
bio: WBCs, UV converted to heat
chemical: low pH, sebum, defensins, melanin
physical: no water and water soluble substances
sensing
contains sensory nerve endings
thermoregulation
vasodilation vasoconstriction
sensible and insensible sweating
