Skin and Integumentary System Flashcards
what are the functions of the integument system?
- protects from: abrasion, infection, UV light, dehydration
- thermal regulation
- sensory reception
- vitamin d production
- communication
where is vitamin d produced?
dermis of skin, after exposure to sunlight
function allows calcium to = absorbed from foods you eat
the skin is the largest …
organ
what 3 layers is the skin divided into?
- epidermis
- dermis
- hypodermis
what is a hypodermic needle?
long hollow needle that reaches all the way from epidermis to dermis
epidermis
- made up of keratinised stratified squamous epithelium
- gives strength to skin
- has no blood supply, so relies on oxygen absorption + nutrients from dermis blood vessels
the nails are made in the ..
epidermis
what are the layers of the epidermis?
- stratum corneum (most superficialities layer)
- stratum lucidum (only thick skin)
- stratum granulosum
- stratum spinosum
- stratum basale (deepest layer of epidermis)
the stratum basale has 4 types of cells
what are they?
keratinocytes
- makes keratin
- keratin = waterproof + strong
merkel cells
- used as sensory receptors for sense of light touch
macrophages
- ingest debris
melanocytes
melanin is produced from the amino acid …
tyrosine
eumelanin
- brown and black pigments found in darker people
- small amounts —> blonde/brown hair
- black pigment without brown —> grey hair tint
pheomelanin (sulphur containing)
- gives pink to red hue
- abundant in lips, nipples + vagina
production of melanin is increased when ..
during pregnancy
what is the function of melanocytes (brown)
make and transport melanosomes for several keratinocytes
have long skinny arms to accomplish this
which 2 mechanisms can melanosomes be passed onto keratinocytes?
- phagocytosis
- endocytosis
tanning
UV light triggers dna damage in keratinocyte nucleus
—> activating p53
regulates expression of gene POMC (proopiomelanocorticon)
what is POMC post translationally processed to produce?
melanocyte stimulating hormone (MSH) + beta endorphin
the stratum basale is the only layer where..
epidermis cells = dividing
what is the stratum spinosum?
old cells that have been pushed up to make the next layer
now attached to each other by desmosomes
cells = alive but don’t divide here
what does the stratum spinosome also contain?
langerhan cells (WBC)
why do cells in the stratum granulosum start to die?
too far from nutrient source in dermis
stratum lucidum
only layer on palm + soles
thin layer —> projection from UV radiation
why do dark skinned people have lighter coloured palms and soles?
in palms + soles, stratum lucidum is present
tan coloured protein blocked underlying melanocytes from view
what is desquamation?
when cells lose their nucleus + fuse to squamous sheets, which are shed from the surface in 2 weeks
in the stratum corneum, the dead cells are filled up with …
keratin
what is keratin?
waxy protein only pound in epidermis
what is the secrete ingredient of all moisturises?
water
what are the 4 stages in skin healing?
- inflammation
- scab formation
- cell division + migration
- scar formation
skin injury + repair
step 1
bleeding happens at injury site
mast cells in region trigger immune response
skin injury + repair
step 2
scab forms
stratum basale cells migrate along edges of wound
phagocytic cells remove remove debris
clotting also happens
skin injury + repair
step 3
scab is undermined by epidermal cells migrating over fibroblast meshwork
fibrin clot disintegrates
skin injury + repair
step 4
scab has been shed + epidermis complete
shallow depression marks injury site
fibroblasts in dermis continue to create scar tissue —> elevate overlying epidermis
what are the 2 types of mechanoreceptor located rose to the surface of the skin?
merkel receptor
- fires continuously whilst stimulus present
- SLOWLY adapting fibre
- responsible for sensing fine details
meissner corpuscle
- fires only when stimulus first applies + when removed
- RAPIDLY adapting fibre
- responsible for controlling hand grip
what are the 2 mechanoreceptors located deeper in the skin?
Ruffini cylinder
- fires continuously
- SLOWLY adapting fibre
- associated with stretching of skin
Pacinian corpuscle
- fires when stimulus first applied + when removed
- RAPIDLY adapting fibre
- associated with sensing rapid vibrations + fine texture
what are C fibres?
unmyelinated nerve fibres found in hairy skin
sensitive to indentation
most active when stimulus moves slowly across skins surface
where are cold receptors located?
epidermis
where are the warm receptors located?
dermis
what are the 3 types of pain?
nociceptive - signals impending damage to skin
inflammatory pain - caused by damage to tissues/joints by tumour cells
neuropathic pain - caused by damage to central nervous system
e.g. brain damage caused by stroke
there are more pain receptors in the…
centre of body
what are the 2 layers in the dermis?
- papillary layer (more superficial)
- reticular layer
papillary layer
- loose connective tissue
- has ridges to inc SA for contact with epidermis
- forms our fingerprints
reticular layer
- dense irregular connective tissue
- gives dermis its strength
- strongest layer of DERMIS
- has lots of collagen + elastin
the stratum spinosum is the strongest layer of the..
epidermis
the meissner corpuscle nerve receptors in the dermis for…
light touch
the pacinian corpuscle nerve receptors in the dermis for …
vibration and pressure
what is the source of collagen for injections?
bovine (cow)
porcine (pig)
human skin
the subcatenous layer - hypodermis
made of loose connective tissue - areolar + adipose
stabilises skin position
contains many fat cells
safely receives hypodermic needles
what are the chief parts of the hair?
root - imbedded in skin
shaft - projects above skins surface
what 3 layers is the hair shaft organised into?
- medulla - central core
- cortex - surround medulla
- cuticle - outermost layer
what is the hair follicle?
root sheath extending from the epidermal surfaces into the dermis
what is the papilla in hair follicles?
nipple shaped indentation with blood vessels and nerves
what is the matrix?
germinal layer of cells right above papilla
what are the functions of hair?
- help maintain warmth
- alter body to presence of insects on skin
- guarding scalp against physical trauma, heat loss + sunlight
each hair is associated with…
- one/more sebaceous (oil) glands
- arrector pili muscle
- plexus of nerves around root
what are the 2 types of sweat (sudoriferous) glands?
merocrine (eccrine)
- all over skin apart from nipples
apocrine
- located only in axillary, pubic and anal regions
- larger than merocrine
- secretes thicker sweat
what is diaphoresis?
sweating with wetness
what are the 2 specially modified sweat glands?
ceruminous
- found in external ear canal
mammary
- milk producing glands found in female breast
- modified apocrine glands
sebaceous glands
occur over all body (except palms and soles)
simple alveolar glands
holocrine secretion
function of the sebum
- softens + lubricates hair and skin
- skin waterproofing
- collects dirt
nails
scale like modification of epidermis made of hard keratin
parts of nail:
- free edge
- body
- root
- nail folds
- eponchyium - cuticle
