Integumentary system

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INTEGUMENTARY SYSTEM Honors Anatomy & Physiology

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Honors Anatomy & Physiology. Integumentary system. What are the ways skin protects the body?. Essential question. functions: protecting the body helping to regulate body temperature allows you to sense stimuli in your environment stores blood synthesis of vit . D - PowerPoint PPT Presentation

Transcript of Integumentary system

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INTEGUMENTARY SYSTEMHonors Anatomy & Physiology

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ESSENTIAL QUESTION What are the ways skin protects the

body?

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INTEGUMENTARY SYSTEM functions:1. protecting the body2. helping to regulate body temperature3. allows you to sense stimuli in your

environment4. stores blood5. synthesis of vit. D6. excretion & absorption of materials

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STRUCTURE OF THE SKIN skin = cutaneous membrane largest organ of body

in adults: covers ~ 2 m² & weighs ~ 4.5 – 5 kg (10 – 11 lb)

2 parts:1. epidermis 2. dermis3. sub Q below dermis & not technically part

of skin: contains fat (insulation), & blood vessels, nerves that supply the skin

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LAYERS OF THE EPIDERMIS

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EPIDERMIS keratinzed stratified squamous

epithelium 4 main cell types:1. keratinocytes2. melanocytes3. Langerhans cells4. Merkel cells

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KERATINOCYTES ~ 90% of all epidermal cells produce fibrous protein: keratin:

protects skin & underlying tissue from heat microbes chemicals

also release a water-repellant sealant from lamellar granules decreases water entry/loss inhibits entry of foreign materials

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KERATINOCYTES

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MELANOCYTES ~8% of epidermal cells produce melanin keratinocytes

pigment (yellow-red to brown-black) that contributes to skin color

* absorbs UV radiation “covers” nucleus in keratinocyte

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LANGERHANS CELLS arise in red bone marrow then migrate

to epidermis easily damaged by UV radiation function: immune response vs.

microbes that invade

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MERKEL CELLS least numerous of epidermal cells

(>1%) deep in epidermis in contact with Merkel disc (tactile disc) together detect different aspects of

touch

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THIN SKIN covers most of body 4 layers:1. stratum basale2. stratum spinosum3. stratum granulosum4. stratum corneum

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THICK SKIN found in areas where exposure to

friction is the greatest “thick” because has 1 extra layer:

stratum lucidum (between stratgum granulosa & a thicker stratum corneum)

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PSORIASIS

common & chronic skin disorder in which keratinocytes divide & move more quickly than normal from stratum basale stratum corneum make abnl keratin flaky, silvery scales @

skin surface most often over knees, elbows, or scalp

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DERMIS 2nd, deeper layer of skin composed mostly of CT 2 regions:1. papillary region2. reticular region

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PAPILLARY REGION OF DERMIS ~ 1/5th of total dermis surface area greatly increased by

finger-like structures: dermal papillae that project into epidermis contain:

capillary loops tactile receptors: Meissner corpuscles free nerve endings (temp, pain, tickle, itch)

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EPIDERMAL RIDGES develop during 3rd month of fetal

development pattern is genetically determined &

unique to individuals (x identical twins) on finger tips ridges deeper finger

prints allow you to grasp things by increasing

surface area

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RETICULAR REGION OF DERMIS attached to subcutaneous layer

beneath contains:

dense irregular CT hair follicles sebaceous glands sudoriferous (sweat) glands collagen & elastic fibers (gives skin its

elasticity, strength): extreme stretching striae (stretch marks)

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BASIS OF SKIN COLOR 3 pigments contribute:1. Melanin2. Hemoglobin (hgb)3. Carotene

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MELANIN made from a.a. tyrosine using enzyme

tyrosinase then stored in organelle called a melanosome

exposure to UV light increases enzymatic activity & more (& darker) melanin produced

melanin absorbs UV radiation preventing it from damaging DNA which skin cancer

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HEMOGLOBIN in RBCs rosy color to lighter skinned

individuals blushing: due to increased blood flow

(autonomic nervous system at work)

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CAROTENE yellow-orange pigment precursor of vit. A

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ALBINISM inherited inability to produce melanin most due to cell’s inability to produce

tyrosinase

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VITILIGO partial or complete lack of melanocytes

from patches of skin produces irregular white spots

? Immune system malfunction?

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SKIN COLOR AS DIAGNOSTIC CLUE cyanotic: when blood not adequately

oxygenated mucous membranes, nail beds & skin appears bluish

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SKIN COLOR AS DIAGNOSTIC CLUE

jaundice: due to build up of bilirubin (yellow pigment) in skin, sclera; usually indicates liver disease

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SKIN COLOR AS DIAGNOSTIC CLUE

erythema: redness of skin caused by engorgement of capillaries due to: injury, infection, inflammation, allergic reaction

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SKIN COLOR AS DIAGNOSTIC CLUE

pallor: paleness of the skin, seen in shock & anemia

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ACCESSORY STRUCTURES OF THE SKIN

all develop from embryonic epidermis include:

Hair Nails Glands

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HAIR (PILI) present on most skin surfaces x palmar

surfaces of hands, soles & plantar surfaces of feet

genetic & hormonal influences determine the thickness & pattern of distribution of hair

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HAIR functions: protection

scalp, eyebrows, eyelashes: from getting foreign objects in eyes

nose, ear canals: trap foreign objects sensitive to light touch

touch receptors in hair root plexus

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ANATOMY OF A HAIR

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HAIR composed of columns of dead,

keratinized cells bonded together by extracellular proteins

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ANATOMY OF A HAIR shaft: portion of hair that projects from

scalp root: portion below scalp follicle: surrounds root of hair arector pili: smooth muscle extends

from side of hair follicle superficial dermis

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TYPES OF HAIR lanuga: grows on fetus @ ~ 5 months

fetal age; sheds b/4 birth

vellus hair: short, fine hair that grows over baby @~ 2-3 months after birth

terminal hair: coarse hair that develops after puberty

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HAIR GROWTH CYCLE

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HAIR COLOR mostly due to amt & type of melanin in

keratinzed cells dark hair has eumelanin blondes & redheads have pheomelanin gray: loss of melanin white: loss of melanin + air bubbles in

shaft of hair

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SKIN GLANDS exocrine glands ass’c with the skin:1. sebaceous glands2. sudoriferous glands

eccrine sweat glands apocrine sweat glands

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SEBACEOUS GLANDS “oil” glands most connected to hair follicles

rest secrete directly onto surface of skin (lips, eyelids, genitals)

secrete oily substance called sebum onto hair

keeps hair from getting brittle

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ACNE inflammation of sebaceous glands

colonized with bacteria infection cyst which destroys

epidermal cells (cystic acne) acne is not caused by eating chocolate

or fried foods

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SUDORIFEROUS GLANDS sweat glands sweat onto skin surface or hair

follicles

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CERUMINOUS GLANDS modified sweat glands in external ear

canal skin (subQ layer) secrete cerumen (ear wax

provides a sticky barrier that impedes entrance of foreign bodies

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NAILS plates of tightly packed, hard, dead,

keratinized epidermal cells that form a clear, solid covering over the dorsal surfaces of the distal portions of the 20 digits

average growth ~ 0.04 in/wk fingernails grow slightly faster than toe

nails

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FUNCTIONS OF A NAIL help us grasp & manipulate small

objects protect ends of digits allows scratching

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PARTS OF EXTERIOR OF A NAIL

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ANATOMY OF A NAIL

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PARTS OF A NAIL body: visible part root: part buried matrix: where cells divide to produce

growth

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FUNCTIONS OF THE SKIN (#7)1. Thermoregulation

the homeostatic regulation of body temperature

skin achieves this in 2 ways:1. sweating

evaporation of sweat requires nrg (body heat) so body cools down as sweat evaporates

2. adjusting flow of blood in dermis vessels dilate when body too warm vessels constrict when body too cold

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FUNCTIONS OF THE SKIN

2. Blood Reservoir skin carries ~ 8 – 10% of total blood

flow in resting adult

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FUNCTIONS OF THE SKIN3. Protection keratin protects underlying tissues from microbes,

abrasion, heat, & chemicals lipids released retard evaporation of water from

skin surface guarding vs. dehydration & retard water from entering thru skin

sebum moistens skin & has antibacterial properties acidic pH of sweat bacteriostatic melanin protects DNA in skin cells from UV damage Langerhans cells alert immune system if microbes

does attack / macrophages ingest microbes

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FUNCTIONS OF THE SKIN4. Cutaneous Sensations skin contains variety of nerve endings

& receptors touch pressure vibration tickle pain temperature

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FUNCTIONS OF THE SKIN

5. Excretion elimination of wastes from the body only small amt substances excreted from

skin ~400 mL water/day ~200 mL sweat (sedentary adult) small amts salts, CO2, NH3, & urea

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FUNCTIONS OF THE SKIN

6. Absorption passage of materials from external

environment body cells absorption of water-soluble materials

negligible lipid-soluble materials do absorb:

fat-soluble vitamins (A, D, E, K) certain drugs (can be administered transdermally) gases: O2 & CO2 toxins: acetone, CCl4, salts of Hg, Pb, Ar,

substances in poison ivy & poison oak

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FUNCTIONS OF THE SKIN

7. Synthesis of Vitamin D requires activation of a precursor molecule in

the skin by UV rays in sunlight modified by enzymes in liver & kidneys producing calcitriol the most active form of vit. D

calcitriol: aids in absorption of calcium in GI tract

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SKIN WOUND HEALING skin damage sets in motion a sequence

of events that repairs the skin to as normal as it can in both structure & function

depending on depth of wound 1 of 2 processes occur epidemal wound healing deep wound healing

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EPIDERMAL WOUND HEALING abrasion: portion of skin has been

scraped away in response to injury: basal cells of nearby

uninjured skin break contact with bm, enlarge, & migrate across the wound migration continues across wound until meet cells

advancing from other side of wound contact inhibition: cells stop migrating when touch

another cell

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DEEP WOUND HEALING when injury extends deeper than

epidermis repair process more complex & scars form

healing occurs in 4 phases:1. Inflammatory phase2. Migratory phase3. Proliferative phase4. Scar formation

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INFLAMMATORY PHASE blood clot forms

loosely unites edges of wound inflammation develops

vascular response vasodilation & increased permeability of

vessels cellular response

phagocytic WBCs (neutrophils), macrophages fibroblasts

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MIGRATORY PHASE clot scab epithelial cells migrate beneath scab to

bridge wound fibroblasts begin secreting collagen &

glycoproteins scar *tissue filling wound called granulation

tissue

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PROLIFERATIVE PHASE extensive growth of epithelial cells

beneath scab & deposition of collagen in random patterns (fibroblasts)

growth of blood vessels

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SCAR FORMATION aka maturation phase scab falls off epidermis restored collagen fibers become more organized fibroblasts disappear blood vessels restored to normal scar tissue less elastic, fewer blood

vessels, +/- accessory structures of skin

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SCARS fibrosis: process of scar formation 2 types raised scars1. hypertrophic scar

scar remains w/in boundaries of wound2. keloid

extends boundaries of wound site

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SCAR FORMATION aka maturation phase scab falls off epidermis restored collagen fibers become more organized fibroblasts disappear blood vessels restored to normal scar tissue less elastic, fewer blood

vessels, +/- accessory structures of skin

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BURNS tissue damage caused by excessive

heat, electricity, radioactivity, or corrosive chemicals that denature proteins in skin cells

destroy skin’s ability to maintain homeostasis

graded by their severity: 1st & 2nd degree = partial thickness burns; 3rd degree = full thickness

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1ST DEGREE BURNS only epidermis is damaged example: sunburn symptoms:

localized redness, swelling, & pain tx: immediate flushing with cool water

(lessens pain) healing: 3 – 6 days +/- peeling of skin results: normal

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2ND DEGREE BURN epidermis & upper dermis damaged,

some skin function lost, ass’c structures not damaged

symptoms: same as 1st degree + blisters (epidermis

separates from dermis due to accumulation of tissue fluid)

example: any burn with blisters

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2ND DEGREE BURNS tx: if 2° infection: antibiotics lasts: 3 – 4 wks with +/- scarring

AVOID: WEAR SUNSCREEN!

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3RD DEGREE BURNS destroys epidermis, dermis, & subQ no initial edema or pain or sensations

(receptors destroyed) most skin functions lost as healing starts marked edema regeneration: months, + scarring tx: +/- skin grafting

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SYSTEMIC EFFECTS OF A BURN greater threat to life than burn itself include:

1. large loss of water, plasma, plasma proteins

shock2. bacterial infection3. reduced circulation of blood4. decreased urine production5. diminshed immune response

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MAJOR BURNS used to estimate extent & severity of

burns major burn considered a 3° burn that

covers > 10% of body or a 2° burn that covers > 25% of surface area of body or any 3° burn on face, hands, feet, or perineum

if burn > 70% surface area > ½ patients die

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RULE OF 9’S

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SKIN CANCER

3 common forms:1. Basal cell carcinoma2. Squamous cell carcinoma3. Malignant melanoma

1 & 2 50% more common in males

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BASAL CELL CARCINOMA > 78% all skin cancers arises in cells from stratum basale

Sun-exposed areas rarely metastasizes.

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SQUAMOUS CELL CARCINOMA ~20% of all skin cancers arise from squamous cells in epidermis variable tendency to metastasize

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MALIGNANT MELANOMA arise from melanocytes ~2% of all skin cancers deadliest form of skin cancer

spreads rapidly, can die w/in months of dx ~1/50 Americans will develop in their

lifetimes (was 1/500 in 1930’s) increase partly due to hole in ozone layer

(more UV rads) main reason: more people spend more

time in sun &/or tanning beds

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MALIGNANT MELANOMA key to successful tx is early detection early warning signs: ABCD A: asymetrical lesion B: borders are irregular C: color is uneven; may have multiple

coloration D:diameter: ordinary moles <0.25 in

(pencil eraser)

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DEVELOPMENT OF THE INTEGUMENTARY SYSTEM

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