Integumentary System
Skin & its appendages (hair, nails, skin glands)
Integument = skin, principle organ of integumentary system
Functions of Skin (cutaneous membrane)
Protection
1st line of defense vs microbes. Tough cells of stratum corneum (thick skin b/c stratified squamous epi’s) protects vs. tears, cuts
Keratin (protein) H2O proof protects vs fluid loss,
keeps fluids in Melanin in pigment layer prevents UV rays from penetrating body
Vit D manufactured in skin w/ sunlight (uvB Rays)helps Ca/P absorption strong bones
Temp Regulation
Regulates sweat secretions sweat evaporates heat lost
Regulates flow of blood close to body surface Blood vessels dilate close to surface heat lost by radiation
Blood vessels constrict heat conserved
Sense Organ
Millions of nerve endings, receivers for body, keep it informed of environmental changes, react to stimuli (pain, pressure, temp, etc)
Structure of the skin Skin is cutaneous membrane: sheetlike organ composed of 2 layers of distinct tissue
Epidermis: Outermost skin layer Thin sheet of stratified squamous epi’s
Dermis: Deeper layer Thicker than epidermis Consists of mostly connective tissue
Subcutaneous Tissue
Loose connective tissue & fat
Not part of skin itself
Carries major blood vessels & nerves to skin above
Rapid, painfree absorption of injected material
Spongy, porous layer
Stratum Basale
EpidermisStratum corneum
Dead, flat cells full of keratinKeratin is waterproof proteinCells are shed/sloughed
Stratum lucidum (lucid = clear↑ apparent in thick skin
3-5 layers of clear cells“Thicker” areasSoles of feet, palms prints
Stratum granulosum3-5 layers Keratinization begins hereCytoplasm replaced w/ tough, H2O proof proteinCells beginning to die
Stratum spinosum 8-10 layers Keratinocytes take in keratin
Stratum basale (stratum germinativum)Single layer of cuboidal to columnar cellsStem cells that produce keratinocytesMelanocytes - # the same for all races
Melanin produced in a melanosomeBasal cell to surface – about 2-4 weeks
Increased [melanocyte] deeper skin color
Sun ↑ melanocytes w/ melanin tan
↑ sun exposure ↑melanin deposits in dermis
[melanin] in relation to blood vol or [O2]
blood flow to skin pink, flush, blush
blood flow to skin bluish gray - cyanosis
*Notice above more w/ less w/ [melanin]
When skin cells deprived of O2 Decubitus UlcerBed SoresTissue breaks down Decubitus Ulcer of Elbow
Cells of epidermis pkd tightly & held together by “spot welds”
(junctions btwn membranes of adjacent cells. If weakened/destroyed skin falls apart) Burns, friction, irritant exposure blisters (top layer raised fluid filled)
Fx in immune response, damaged by UV radiationContains
melanin skin color, absorbs UV radiation
90% of epidermis
Merkel cells in deep in epidermis hairless areas ? Fx in touch sensation
*Merkel cell in deepest layer of hairless skin ? Fx in touch sensation
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Dermal-Epidermal Junction: junction between thin epidermal layer of skin above and thicker dermal layer below
2. Dermis: Deeper of 2 primary layers Much thicker, Made mostly of connective tissue Cells scattered w/ fibers in between, not pkd like Epidermis
Fibers: some tough & strong others stretchable, elastic
Upper Dermis: Dermal Papillae // rows of peglike projections
Important part of dermal-epidermal junction helps bind 2 skin layers together
Forms ridges & grooves fingerprinting/ID Epidermis follows contours of dermal papillae Develop before birth, unique, individual, never changes but to grow larger fingerprints & footprints (+ ID)
Deeper area of dermis filled w/ dense network of interlacing fibers collagenous giving toughness to skin
Elastic fibers also present stretchable, elasticity Age, ↓ # of elastic fibers in dermis, amt fat stored in subcutaneous tissue wrinkles…loss of elasticity, sags, pliant
(botox, collagen injections, retinol, ↑ collagenous fibers ↓ wrinkles!
Appendages of the skin
Hair: human body covered w/ hair
At birth, most follicles required for hair growth present
Lanugo: newborn hair, fine & soft, lost & replaced w/ new, stronger & more pigmented hair
Lips, palms, soles hairless
Most body hair invisible
Most visible on scalp, eyelids, eyebrows
Pubic & Axillary (under arm) hairs develops w/ puberty (result of hormone secretions)
Cells of epidermis grow ↓ into Dermis forming hair follicle (sm tube)
Hair growth begins from cluster of cellsHair Papilla located at follicle base
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Papillanourished by a dermal blood vesselRoot hidden in follicleShaft (dead cells)visible part of hair
As long as cells in Papilla alive, newHair replaces pluckedNeither makes hair Grow faster of effects epithelial cellsThat form hairs b/c they’re embedded in dermis
Depilliatories destroy protein in hair shaft (Ex. Nair)
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Arrector Pili(Errects hair)Smooth/involuntarymusclesAttached at base of dermal papillaabove & to side of follicle Frightened or cold contract
Each muscle pulls on 2 points of attachmentup on hair follicle,down on part of skin goose bumps
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Sensory Receptors: allows body surface to act as sense organ Relays messages to brain, sensations of pain, temp, pressure Meissners Corpuscle: dermis surface, light touch Pacinian Corpuscle: deep dermis, detects pressure
Thermoreceptors: temp receptors in skin (detect stimulus & send impulse to hypothalamus (control center) in brain (Uses – feedback loop, like thermostat)
Nails: accessory organs of skin, produced by cells in epidermis. Epidermal cells over terminal ends of fingers/toes fill w/ keratin (protein) hard, plate like
Nail Plate/Body: visible part of nail Root: lies in groove, hidden by fold (cuticle)Luna: (little moon) crescent shaped white area near rootNail Bed: under nail, thin layer of epithelium has blood vessels pink & translucent blood (O2) cyanosis blue nail bed free edge
Skin Glands
Sweat / Sudoriferous Glands: most numerous
eccrine sweat glands (most) sm. distributed all over body surface produce perspiration/sweat eliminates wastes (NH3, UA, maintains BT) 1 sq inch = 3000 eccrine glands pores (outlets of small ducts)
apocrine sweat glands 10 in armpit & pigmented skin @ genitals. (scent glands)Lgr vs eccrine & secrete thicker, milky secretions,
odor from contamination & decomposition of secretion by skin bacteria. Enlarge / function @ puberty
Most numerous
Armpits, pigmented areas, genital areas
Oil glands, secrete sebum, ↑’s after puberty (opens to hair follicles)
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Sebum ↑ during adolescence, stimulated by ↑ blood levels of sex hormones
Sebum accumulates, enlarges duct of sebaceous gland white pimples darkens blackhead
Acne Adolescence overactive secretion of sebaceous glands w/ blockage & inflammation of ducts Ages 10-19…5x sebum secretion sebaceous gland ducts get plugged w/ skin cells & sebum w/ bacteria comedo (pus filled pimples from 20 infection w/in or beneath epidermis in hair follicle or sweat pore
Sebaceous Glands: Secrete oil (sebum) for hair & skin, Found wherever hair grows Tiny ducts open to hair follicles
Secretion: Sebum, lubricates hair/skin
Milia: sm white bumps on newborn, accumulation of sebaceous gland material Vernix Caeseosa: oily substance produced by fetus’s sebaceous glands
Burns fire, heat, UV light, chemicals, electrical
Burns, treatment & recovery depend on: Total area involved Severity of burn … determined by depth of injury & amt of body surface affected
*Treatment Prevent fluid loss & infection Skin Grafts cultured
Estimating Body Surface: (% body surface burned)
Rule of 9’s to determine extent of burn injury
Body divided into 11 areas of 9% each + 1% genitals Total = 100%Head front 4.5% back 4.5%
Arms front 4.5% (x2) 9.0 back 4.5% (x2) 9.0
Torso front 18% back 18%
Legs front 9% (x2) 18.0 back 9% (x2) 18.0
genitals 1%
Burn Classification:
Based on # of tissue layers involved
1st degree: Sunburn, minor discomfort, skin red surface layers of epidermis may peel 1-3d No blistering Minimal tissue destruction
2nd degree: Involves deep epidermal layers Always causes injury to upper layer of dermis Damage sweat glands, hair follicles, sebaceous glands, BUT NOT complete dermis destruction Blisters, severe pain, swelling, fluid loss, scarring common
3rd degree: Complete destruction of epidermis/dermis, tissue death extends below 10 skin layers into subcutaneous tissue, muscle & bone. Insensitive to pain (destruction of nerve endings) serious scarring
Types of Body Membranes
Membrane: Thin, sheet-like structure
Cover & protect body surfaceLine body cavitiesCover inner surfaces of organs (dig, reprod, resp) Anchor organs to each other or bonesCover internal organsSome membranes secrete lubricating fluids to ↓ friction during organ movements (Ex. heart beating, lung expansion/contraction, in joints between bone)
2 Main Types of Body Membranes Epithelial Membranes Connective Membranes
Cutaneous membranes Synovial membranesSkin (Integumentary)
Serous membranes
Mucous membranes
Epithelial Membranes
a. Cutaneous membranes: (Epidermis/Dermis) skin
10 organ of integumentary system
skin outer epidermis composed of stratified squamous epithelial cells
underlying epidermis is dermis made of connective tissue
subcutaneous
Epithelial Membranes cont’db. serous membranes: 2 distinct tissue layers
(secrete thin watery fluid helps ↓ friction lubricant)
1. epithelial sheet: thin layer simple squamous epi’s
2. connective tissue layer: basement membrane supports epi’s
2 Types of serous membranes Parietal lines walls of body cavities Visceral covers surface of organs in cavities
Pleura: Serous membrane of thoracic cavity
Peritoneum: Serous membrane of abdominal cavity
(lines cavities) (covers organs)parietal & visceral pleura (of thoracic cavity)parietal & visceral peritoneum (of abdominal cavity)
pleurisy: inflammation of serous membranes (pleura) lining chest cavity (parietal) and covering lungs (visceral)
pain friction of lungs rubbing vs. walls of chest cavity
peritonitis: inflammation of serous membranes lining abdominal cavity (parietal) and covering abdominal organs (visceral) Sometimes from infected appendix
Epithelial Membranes cont’dc. Mucous Membranes: Line body surfaces open to outside Structure depends on location Most secrete mucus moist, lubricate, protect keeps soft
Respiratory: Ciliated simple columnar epi’s mucus Digestive: Esophagus: stratified epi’s resist abrasion Intestines: simple columnar epi’s Urinary/Excretory: simple cuboidal absorption Reproductory
Connective Tissue Membranes
No Epithelial component
Synovial Membranes: Line joint spaces between bone
Smooth, slick
Secrete synovial fluid
Line bursae sacs (cushion)
between moving parts
↓ friction between joints
Now, Brain Storm
and think of as many examples of how structure dictates function
as you can,then explain them!