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cutaneous membrane
epithelial membrane
Epithelial layer → stratified squamous cells
Connective layer → thick layer of dense connective tissue
Only epithelial membrane is directly exposed to air
mucous membrane
epithelial membrane
Location: lines body cavities that is open to exterior
Epithelial layer varies (not usually adapted or absorb or secretion)
Connective layer: loose connective tissue
wet/moist membrane → bathed in secretion
serous membrane
epithelial membrane
Location: lines interior organ & cavities
Epithelial layer: simple squamous
Connective layer: loose connective tissue (areolar)
wet/moist membrane found in closed ventral body cavities
Named according to site organ it overs
synovial membrane
connective membrane
made of loose areolar connective tissue & contain NO EPITHELIAL LAYER
Line capsule surrounding joints
Secrete fluid that helps lubricate joint
epidermis
epithelial tissue that is stratified squamous (20 layers thick)
stratum corneum
nickname: hornlike/horny layer
20-30 layer
contain many layers of dead keratinocytes
outermost layer → constantly shedding
hands & feet most wear & tear
stratum lucidum
nickname: clear layer
2-3 layer
only found in thick skin (palms & soles)
stratum granulosum
nickname: granular layer
2-4 layers
keralinization occurs (production of keratin) - cell fill w/ protein & cause nucleus to shrivel & cell slowly die
stratum spinosum
nickname: spiny/pricky layer
8-10 layer
finishes process of mitosis that was started in layer below
stratum germinativum/basale
nickname: base/basal layer
1 layer (columnar/cubodial cells)
cells are actively dividing by mitosis to produce cells that will migrate to top
all type of cells are found here
keratinocytes
90%
location: found throughout all epidermis layers
produces keratin
mature keratinocytes at skin surface → all are dead & filled almost entirely of kertain
melanocytes
8%
location: found in stratum basale
makes up color of skin
act as shield to protect from reaching nucleus (tan)
produces melanin
melanin is transferred to keratinocytes
melanin (once inside kerantinocytes) cluster around nucleus on surface side → shield DNA
Langerham cells
1%
location: stratum spinosum & basale
protects alive cells (security guard)
part of immune response in skin, interacts w/ white blood cells to get rid of foreign bodies (ingest foreign bodies)
injury: calls in white blood cells
merkel cell
1%
location: stratum basale
form merkel discs which w/ nerve endings, serve as sensory function
allow you to feel light touch
dermis
largest of the 2 layers of integumentary system
located below epidermis & basement membrane
contain: blood vessels, lymph vessels, appendages (glands, hair, nails), sensory organs & collagen/elastic fibers
papillary layer
top layer (loose areolar tissue
top portion consist of finger-like projections → papillae
increase surface area & help diffuse O2 + nutrients to epidermis
have either blood vessels OR Meissener’s corpuscles
double row → fingerprints
reticular layer
2nd layer, thickest sublayer → hold collagen & elastic fibers
contain: pacinian corpuscles (deep pressure touch sensor), sweat glands, oil glands, blood vessels, lymph vessels, hair follicles & smooth muscle
Meissener’s corpuscles
light touch sensation
Pacinian Corpuscles
deep touch sensation
hypodermis (subdermis)
subcutaneous tissue
NOT part of integumentary system
made of loose connective tissue & adipose
function: help anchor skin & store fat
body temperature regulation
if external temp. less than body temp → skin surface lose heat to air
in normal temp, sweat glands continously secrete unnoticeable amounts of sweat
body temp rise → dermal blood vessels dilate & sweat glands stimulate to secrete more
body temp drop → dermal blood vessels will constrict
allow warm blood to bypass skin & skin temp drop to external environment → heat loss slow down
cutaneous sensation
sensory reception found all over skin & respond to stimuli outside of body → communicate info to nervous system
(ex. meissner’s corpuscles, Pacinian Corpuscles, hair root plexuses & merkel cells)
metabolic functions
in presense of UV light from sun, Vitamin D molescules made from precursor molecules accumulating in skin
too little & too much = not good
blood reservoir
blood supply in dermis can hold relative large amount of blood
working muscle need greater blood supply → dermis blood vessels are constricted & give more blood to needed muscles & organs
how a person’s muscles get bigger
excretion
small amounts of wastes are eliminated from body in sweat (most exit through urine)
sweat is an important revenue for water & salt homeostasis
protection
outerskin surface forms physical barrier to infection/pathogen
contain waterproof layer, barrier to water-soluble substances
protect organs & area below surface
melanin pigments protect us from sun
sebaceous (oil gland)
mostly connected to hair follicle (a few places directly to surface)
absent in palms & soles (thick skin)
function: secrete sebum → coat hair (help it from drying out/ being brittle)
sudoriferous (sweat) glands
3-4 million arond body & they can be divided into 2 main subcategories → eccrine/ merocrine & apocrine
eccrine/ merocrine
location: secreting area in dermis & sweat travel through duct to surface of epidermis to pores on face/ body surface
function: regulate body temp through evaporatiokn
made of: 99% water, electrolytes & waste products
apocrine
location: secrete sweat through hair follicle; mainly through armpit & anogenial areas
function: form of communication
made of: 99% water, electrolytes, waste products, AND lipids & protein
nail
tightly packed, hard, dead keratinized cells → has 3 main parts: free edge, nail body & nail root
most of nail is pink because epidermis is thin & can see blood flowing in dermis
lunula
white because epidermis is thicker in region
free edge
white because there are no longer capillaries under it(has grown passed edge of dermis)
shaft
superficial portion of hair
root
located in dermis/ subcutaneous layer → where new cells/ hair are forming
follicle
surround root
medulla
sometimes lacking in thin hair; normllaly 2-3 layers of cell
cortex
major part of the shoft & root, thickest of the 3 layers
cuticle
outermost layer, a single layer of flat/ heavy keratinized cells →arranged like shingles on a roof
hair follicle
surround the hair root & stans in dermis
contains:
blood vessels
oil/ sebceous glands
hair root plexuses
arrector pili