Question | Answer |
3 major skin regions | epidermis, dermis, hypodermis |
superficial skin region | epidermis |
middle skin region | dermis |
deepest skin region | hypodermis, subcutaneous layer under skin, mostly adipose tissue |
keratinized stratified squamous epithelium | epidermis |
contains melanocytes that produce skin pigment | epidermis |
5 layers of epidermis, bottom to top | stratum basale, spinosum, granulosum, lucidum, corneum |
deepest layer firmly attached to dermis | stratum basale |
single row of stem cells that undergo rapid division | stratum basale |
web-like system of intermediate filaments attached to desmosomes | stratum spinosum |
abundant melanin granules and dendritic cells | stratum spinosum |
thin, 3 to 5 cell layers where cells flatten | stratum granulosum |
keratohyaline and lamellated granules accumulate | stratum granulosum |
only on think skim, palmar, plantar | stratum lucidum |
thin, clear band above stratum granulosum | stratum lucidum |
3/4 thickness of epidermis | stratum corneum |
protects from abrasion and penetration, waterproofs, acts as barrier | stratum corneum |
strong flexible connective tissue (dense regular), cells include fibroblasts, macrophages, mast cells, white blood cells | dermis |
2 layers of the dermis | papillary layer, reticular layer |
areolar connective tissue with collagen and elastic fibers and blood vessels | papillary layer |
dermal papillae contain capillary loops and free nerve endings | papillary layer |
80% thickness of the dermis | reticular layer |
collagen fibers provide strength and resiliency | reticular layer |
elastic fibers provide stretch-recoil properties | reticular layer |
2 types of sweat/sudoriferous glands | eccrine and apocrine |
glands that release sweat | eccrine glands |
ducts connect to pores | eccrine glands |
glands confined to axillary and anogenital areas | apocrine glands |
release sebum | apocrine glands |
sweat + fatty substances + protein | sebum |
glands functional from puberty on | apocrine glands |
secrete cerumen (wax) | ceruminous glands |
produce milk | mammary glands |
widely distributed glands, develop from hair follicles, secrete sebum | sebaceous/oil glands |
dead keratinized cells | hair |
hair pigments | melanins |
sensory nerve endings around each hair bulb, stimulated by bending hair | hair follicle receptor (root hair plexus) |
smooth muscle attached to follicle, responsible for goose bumps | arrector pili |