The Integumentary System

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