epidermis characteristics
stratified, keratinized, squamous, avascular, 5 layers
epidermis consists of what kinds of cells
keratinocytes, melanocytes, Langerhans cells, & Merkel cells
melanocytes composition & function
pigment: melanin, protects from UV
Langerhans cells function
immune response: attracting & phagocytosing microbes, present antigens to T lymphocytes
Merkel cells responsible for
sensation of touch
stratum basale function
“germinativum”; cells capable of division
stratum spinosum function
“prickle cell layer”; strength & flexibility
stratum granulosum function
“granular layer”; apoptosis, keratin, Odland’s bodies
Odland’s bodies produce
lipid to help cells stick together
stratum lucidum function & places found
waterproofing; fingertips, palms, soles
stratum corneum goes through
shedding continuously; singly or in clumps (squamae)
dermis characteristics
lymph vessels, nerve endings, hair, glands, 2 layers, collagen, elastin, blood vessels, nails
dermis function
provide nutrients & physical support to epidermis
how is a blister formed
separation of dermis & epidermis, fluid accumulation due to friction
reticular layer consists of
collagen & elastic fibers
papillary layer consists of
nerves & capillaries
collagen function
prevents tearing, thick
elastin function
allows elasticity; made of fibroblasts, thin
eccrine gland function & places found
thermoregulation through sweat; forehead, palms, soles
apocrine gland function & places found
sex hormones during puberty -> viscous sweat that produces odor; groin, areolae, beards
sebaceous gland function & places found
secrete sebum to protect hairs from drying; hair follicles, face, neck, back
overproduction of sebum creates
comedones (black/whiteheads)
ceruminous gland function
produce waxy, lubricating secretion for external ear
cerumen function
waterproofing & foreign body protection via sticky barrier working with hairs of ear
superficial plexus blood vessels supply
epidermis & dermis
deep plexus blood vessels supply
dermis & subcutaneous layer, small tributaries: hair follicles, sweat glands, etc.
hair matrix responsible for
growth of existing hairs & new hair production
arrector pili function
muscle responsible for goosebumps
nail composition & function
sheets of keratin, protect ends of digits & performance of intricate movements
sensory functions
cold, head, pain, touch, pressure
thermoregulation controlled by
hypothalamus (forebrain)
insulation/warming happens by
subcutaneous adipose tissue; vasoconstriction
sweating happens by
eccrine glands; cool via evaporation, radiation, conduction, convection
protection functions
physical barrier, prevent loss of fluids, prevent colonization of harmful microorganisms
Vitamin D synthesis happens by
UV light
Vitamin D importance
controls amount of Ca & P absorbed through SI and mobilized from bone
Vitamin D deficiency in kids
Ricketts
Vitamin D deficiency in adults
osteomalacia