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!