lecture 2 - Integumentary system Flashcards
what are the functions of the skin
- resistance to trauma
- H2O barrier
- vitamin D synthesis
- sensation
- non-verbal communication
what are the 3 main layers of the skin
epidermis, dermis, hypodermis
epidermis
outer, stratified squamous epithelium
dermis
deeper, connective tissue layer
hypodermis
deep connective tissue below dermis
keratin-protein
cells at skin surface containing tough keratin protein
what is the main cell type of the epidermis
keratinocytes
stratum basale
single layer of stem cells and keratinocytes resting on basement membrane
stratum spinosum
several layers of keratinocytes joined by desmosomes and tight junctions
stratum granulosum
three to five layers of flat keratinocytes
stratum lucidum
keratinocytes packed with clear protein eleidin
stratum corneum
several layers of dead, scaly, keratinized cells
function of stratum corneum
resists abrasion, penetration, water loss
stem cells
stem cells
undifferentiated cells that give rise to keratinocytes
keratinocytes function
synthesise keratin
melanocytes function
synthesise melanin - shields DNA from UV radiation
dendritic cell function
guard against pathogens
tactile cells
touch receptors cells associated with dermal nerve fibres
ichthyosis
genetically inherited disorder which results in the build up of dead cells around the body
eczema
chronic, inherited, inflammatory skin condition which results in dry, itching and reddened skin
exfoliative shedding
excessive shedding of skin
dermis
connective tissue layer beneath epidermis
dermal papillae
upward, finger-like extensions of dermis
epidermal ridges
downward waves of epidermis
papillary layer of epidermis
thin areolar tissue in and near dermal papilla
function of papillary layer
allow mobility of leukocytes and other defence cells
reticular layer of papillary layer
dense, irregular connective tissue
functions of subcutaneous fat
energy reservoir, thermal insulation
what causes different skin tones
the proportion of melanin granules throughout the skin ( dermis)
cyanosis
blueness due to oxygen deficiency
albinism
pale skin and blue-gray eyes due to genetic lack of melanin synthesising enzyme
erythema
redness due to increased blood flow to the skin
jaundice
yellowing due to bilirubin in blood
hair
slender filaments of keratinised cells growing from follicle in skin
hair bulb
swelling at the base of the hair follicle where hair originates in dermis
hair root
the remainder of the hair in the follicle
hair shaft
the proportion above the skin surface
hair matrix
region of mitotically active cells immediately above papilla
dermal papilla
bud of vascular connective tissue encased by bulb
hair receptors
sensory nerve fibres entwining follicles
piloerector muscle
smooth muscle attaching follicle to dermis
function of piloerector muscle
make hair stand up on end
alopecia
thinning of the hair or baldness
pattern baldness
hair lost from select regions
hirsutism
excess hair in areas that are not usually hairy
fingernails
clear, hard derivatives of stratum corneum
functions of fingernails and toenails
- assist with grooming, picking apart food, other manipulations,
- provide counterforce to enhance sensitivity of fleshy fingertips to tiny objects
what are fingernails composed of
thin, dead cells packed with hard keratin
nail plate
hard part of the nail
nail body
visible attached part of nail
nail root
extended section of nail underlying skin
nail fold
surrounding skin rising above nail
nail groove
separates nail fold from nail plate
nail bed
skin underlying the nail plate
hyponychium
epidermis of nail bed
nail matrix
growth zone of stratum basale at proximal end of nail
lunule
opaque white crescent at proximal end of nail due to thickness of matrix
location of apocrine sweat glands
groin, anal region, axilla, areola, beard area in men
eponychium ( cuticle)
narrow zone of dead skin overhanging proximal end of nail
bromhidrosis
body odour produced by bacterial action on sweat from apocrine glands
myoepithelial cells
contract in response to stimulation by sympathetic nervous system
sweat
protein free filtrate of blood plasma produced by deep secretory portion of gland
diaphoresis
sweating with wetness of the skin
insensible perspiration
sweating with no wetness of the skin
sebaceous glands
flask shaped glands that have short duct openings into hair follicles
sebum
oily secretion of sebaceous glands
lanolin
sheep sebum
function of sebum
keeps skin and hair from becoming dry, brittle and cracked
mammary glands
milk-producing glands
basal cell carcinoma
lesion is small, shiny bump with central depression and beaded edges
squamous cell carcinoma
raised, reddened, scaly appearance later forming concave ulcer
melanoma
black spot with dark purple middle and bubbled
debridement
removal of eschar
first-degree burns
burn to the epidermis
second-degree burns
partial-thickness burn; involves part of dermis
heal time of 1st degree burn
days
heal time of 2nd degree burns
2 weeks to several months
third-degree burns
full thickness burn; involve epidermis, dermis and often some deeper tissues
stages in the healing of a skin wound
- blood clot forms
- form scab that temporarily seals wound and blocks infection
- macrophages phagocytise and digest tissue debris
- new capillaries sprout from nearby vessels
- deeper portions of clot become infiltrated by capillaries and fibroblasts
- transforms into soft mass called granulation tissue
- macrophage remove blood clot
- fibroblasts deposit new collagen
- epithelial cells multiply and migrate beneath scab
- underlying connective tissue undergoes fibrosis
- scar tissue may or may not show through epithelium