INTEGUMENTARY INTEGUMENTARY SYSTEMSYSTEM

INTRODUCTIONINTRODUCTION

The integumentary system is made up of the The integumentary system is made up of the skin, hair, nails, and various glandsskin, hair, nails, and various glands

- when something goes wrong with your skin, it - when something goes wrong with your skin, it is apparent right awayis apparent right away

- physicians pay attention to the skin because - physicians pay attention to the skin because any changes could be signs of a disorder or any changes could be signs of a disorder or problem with another body systemproblem with another body system

STRUCTURE AND FUNCTIONSTRUCTURE AND FUNCTION

The integument has 2 major components:The integument has 2 major components:

1. CUTANEOUS MEMBRANE- 1. CUTANEOUS MEMBRANE- or skin; an organ or skin; an organ composed of the EPIDERMIS (superficial composed of the EPIDERMIS (superficial epithelium) and underlying connective tissues of epithelium) and underlying connective tissues of the DERMISthe DERMIS

2. ACCESSORY STRUCTURES- include hair, nails, 2. ACCESSORY STRUCTURES- include hair, nails, and a variety of exocrine glandsand a variety of exocrine glands

- below the dermis is the SUBCUTANEOUS LAYER, - below the dermis is the SUBCUTANEOUS LAYER, which attaches integument to deeper structures which attaches integument to deeper structures (muscle and bone)(muscle and bone)

There are 5 major functions of the integument:There are 5 major functions of the integument:

1. Protection- skin protects underlying tissue and 1. Protection- skin protects underlying tissue and organs from impact, chemicals, infection; prevents organs from impact, chemicals, infection; prevents loss of body fluidsloss of body fluids

2. Temperature maintenance- 2. Temperature maintenance- skin regulates heat gain skin regulates heat gain or loss to environmentor loss to environment

3. Making and storing of nutrients- epidermis makes 3. Making and storing of nutrients- epidermis makes vitamin D, which aids in uptake of calcium; dermis vitamin D, which aids in uptake of calcium; dermis contains large amounts of lipids (fats) in adipose contains large amounts of lipids (fats) in adipose tissuetissue

4. Sensory reception- 4. Sensory reception- receptors detect pain, receptors detect pain, pressure, and temperature stimuli and relay pressure, and temperature stimuli and relay that info. to the nervous systemthat info. to the nervous system

5. Excretion and secretion- excretes salts, water, 5. Excretion and secretion- excretes salts, water, organic wastes; produces milkorganic wastes; produces milk

EPIDERMISEPIDERMIS

The EPIDERMIS consists of stratified squamous The EPIDERMIS consists of stratified squamous epitheliumepithelium

- WHAT DOES STRATIFIED MEAN?- WHAT DOES STRATIFIED MEAN?

- in THICK SKIN (palms of hands and soles of - in THICK SKIN (palms of hands and soles of feet) there are feet) there are 5 layers5 layers

- - in THIN SKIN (covers rest of body) there in THIN SKIN (covers rest of body) there are only 4 layersare only 4 layers

STRATA OF EPIDERMISSTRATA OF EPIDERMIS

STRATA IS ANOTHER NAME FOR LAYERSSTRATA IS ANOTHER NAME FOR LAYERS

In order from the basement membrane toward In order from the basement membrane toward the surface are:the surface are:

Stratum germinativumStratum germinativum

Intermediate strata (3 layers)Intermediate strata (3 layers)

Stratum corneumStratum corneum

STRATUM GERMINATIVUMSTRATUM GERMINATIVUM

- - deepest epidermal layerdeepest epidermal layer

- attached to basement membrane by a type of - attached to basement membrane by a type of desmosomedesmosome

- - basement membrane separates the epidermis basement membrane separates the epidermis from the dermisfrom the dermis

- this layer forms EPIDERMAL RIDGES which - this layer forms EPIDERMAL RIDGES which extend into the dermis, increasing area of contact extend into the dermis, increasing area of contact between the 2 regionsbetween the 2 regions

- - contours of the skin follow these ridge contours of the skin follow these ridge patternspatterns

- these ridges in the palms and soles increase - these ridges in the palms and soles increase surface area of the skin, and help ensure gripsurface area of the skin, and help ensure grip

Ridge patterns are GENETICALLY Ridge patterns are GENETICALLY DETERMINED, and do not change over a DETERMINED, and do not change over a lifetimelifetime

FINGERPRINTS!FINGERPRINTS!

You also find large stem cells (germinative cells) in You also find large stem cells (germinative cells) in the stratum germinativum, so this is the layer the stratum germinativum, so this is the layer where new cells are generated and begin to growwhere new cells are generated and begin to grow

- - these cells replace those lost or shed at the these cells replace those lost or shed at the surfacesurface

- also contains MELANOCYTES- receptors provide - also contains MELANOCYTES- receptors provide info. about objects touching the skin; make info. about objects touching the skin; make MELANIN- MELANIN- a pigment that colors the epidermisa pigment that colors the epidermis

INTERMEDIATE STRATAINTERMEDIATE STRATA

- made up of 3 layers; each becoming specialized - made up of 3 layers; each becoming specialized to form outer protective covering of skinto form outer protective covering of skin

- find the protein KERATIN here:- find the protein KERATIN here:

* extremely durable and water-resistant* extremely durable and water-resistant

* * coats the surface of the skin, forms basic coats the surface of the skin, forms basic

structure of hair, calluses, and nailsstructure of hair, calluses, and nails

STRATUM CORNEUMSTRATUM CORNEUM

- - outermost layeroutermost layer

- consists of 15-30 layers of flattened, dead - consists of 15-30 layers of flattened, dead epithelial cells that have large amounts of epithelial cells that have large amounts of keratin keratin these cells are said to be these cells are said to be KERATINIZEDKERATINIZED

- dead cells in each layer are tightly connected by - dead cells in each layer are tightly connected by desmosomes desmosomes are usually shed in sheets are usually shed in sheets rather than individuallyrather than individually

TIMELINETIMELINE

It takes about 2-4 weeks for a cell to move from the It takes about 2-4 weeks for a cell to move from the stratum germinativum to the stratum corneumstratum germinativum to the stratum corneum

- cell is removed from its oxygen and nutrient - cell is removed from its oxygen and nutrient supply, is filled with keratin, and finally diessupply, is filled with keratin, and finally dies

- - dead cells usually remain in the stratum dead cells usually remain in the stratum corneum for about 2 weeks before they are shedcorneum for about 2 weeks before they are shed

- as these layers are lost, they are replaced from - as these layers are lost, they are replaced from belowbelow

SKIN COLORSKIN COLOR

Skin color is caused by interaction between:Skin color is caused by interaction between:

1. 1. epidermal pigmentsepidermal pigments

2. 2. dermal blood supplydermal blood supply

PIGMENTATIONPIGMENTATION

The epidermis has varying amounts of the two The epidermis has varying amounts of the two pigments CAROTENE and MELANINpigments CAROTENE and MELANIN

CAROTENE- CAROTENE- orange-yellow pigment that orange-yellow pigment that normally accumulates in dermal cellsnormally accumulates in dermal cells

- these pigments are found in vegetables such as - these pigments are found in vegetables such as carrots (eating a large amount of carrots can carrots (eating a large amount of carrots can turn your skin orange!)turn your skin orange!)

- can be converted to vitamin A which is - can be converted to vitamin A which is required for normal maintenance of epithelial required for normal maintenance of epithelial tissuetissue

MELANIN- MELANIN- brown, yellow-brown, or black brown, yellow-brown, or black pigment produced by melanocytespigment produced by melanocytes

- melanocytes make and store melanin and inject - melanocytes make and store melanin and inject it into the epithelial cells of the stratum it into the epithelial cells of the stratum germinativum and intermediate stratagerminativum and intermediate strata

- - this colors the entire epidermisthis colors the entire epidermis

Melanocyte activity increases after sunlight Melanocyte activity increases after sunlight exposureexposure

FRECKLES- represent areas of larger-than-FRECKLES- represent areas of larger-than-average melanin productionaverage melanin production

- - most abundant on surfaces exposed to sunmost abundant on surfaces exposed to sun

ULTRAVIOLET (UV) ULTRAVIOLET (UV) RADIATIONRADIATION

A small amount of UV radiation is beneficial A small amount of UV radiation is beneficial because it stimulates the making of vitamin Dbecause it stimulates the making of vitamin D33

- - too much UV radiation produces burnstoo much UV radiation produces burns

- melanin helps to prevent skin damage by - melanin helps to prevent skin damage by absorbing UV radiation before it can reach the absorbing UV radiation before it can reach the deep layers of the integumentdeep layers of the integument

- - despite this protection, long-term damage can despite this protection, long-term damage can result, even in individuals with dark skinresult, even in individuals with dark skin

EFFECTS OF UV EXPOSURE:EFFECTS OF UV EXPOSURE:

- alterations in underlying connective tissue can cause - alterations in underlying connective tissue can cause premature wrinklingpremature wrinkling

- skin cancers can result from chromosomal damage to - skin cancers can result from chromosomal damage to stem cellsstem cells

* * one major consequence of depletion of the ozone one major consequence of depletion of the ozone layer has been an increase in rates of skin cancerlayer has been an increase in rates of skin cancer

* WEAR SPF OF AT LEAST 15; HIGHER FOR * WEAR SPF OF AT LEAST 15; HIGHER FOR BLONDES AND REDHEADSBLONDES AND REDHEADS

DIFFERENCES IN SKIN DIFFERENCES IN SKIN COLORCOLOR

Differences in skin color between individuals is not Differences in skin color between individuals is not due to the due to the number of melanocytes, number of melanocytes, but to the but to the different levels of melanin productiondifferent levels of melanin production

- - in the inherited condition albinism melanin is not in the inherited condition albinism melanin is not produced by melanocytesproduced by melanocytes

DERMAL CIRCULATIONDERMAL CIRCULATION

- Blood having a lot of oxygen is bright red, and blood - Blood having a lot of oxygen is bright red, and blood vessels in the dermis give the skin a reddish tint that vessels in the dermis give the skin a reddish tint that is most obvious in light-skinned individualsis most obvious in light-skinned individuals

- - when vessels are dilated (during when vessels are dilated (during inflammation), red tones become more inflammation), red tones become more pronouncedpronounced

- when vessels are constricted (frightened), skin - when vessels are constricted (frightened), skin becomes palebecomes pale

- during a prolonged reduction in circulation, - during a prolonged reduction in circulation, blood loses oxygen and becomes dark red, blood loses oxygen and becomes dark red, then blue then blue CYANOSISCYANOSIS

VITAMIN DVITAMIN D33

Limited exposure to the sun is beneficial:Limited exposure to the sun is beneficial:

- - epidermal cells in stratum germinativum and epidermal cells in stratum germinativum and intermediate strata convert a steroid into intermediate strata convert a steroid into VITAMIN DVITAMIN D33

- this is modified and converted into a hormone called - this is modified and converted into a hormone called CALCITRIOL which is essential for the absorption CALCITRIOL which is essential for the absorption of calcium and phosphorus by the small intestineof calcium and phosphorus by the small intestine

- - deficiency of vitamin Ddeficiency of vitamin D33 causes abnormal bone causes abnormal bone

growthgrowth

SKIN CANCERSKIN CANCER

BASAL CELL CARCINOMA- malignant BASAL CELL CARCINOMA- malignant cancer that originates in the stratum cancer that originates in the stratum germinativumgerminativum

- - most common typemost common type

SQUAMOUS CELL CARCINOMAS- less SQUAMOUS CELL CARCINOMAS- less commoncommon

- - metastasis seldom occurs in either; survival metastasis seldom occurs in either; survival is goodis good

MELANOMAS- seldom-occurring and life-threateningMELANOMAS- seldom-occurring and life-threatening

- usually begin from moles, but may appear anywhere - usually begin from moles, but may appear anywhere in the bodyin the body

- - can grow rapidly and metastasize through the can grow rapidly and metastasize through the lymphatic systemlymphatic system

- survival depends on when condition is detected and - survival depends on when condition is detected and treated treated

- - AVOIDING UV RADIATION CAN PREVENT AVOIDING UV RADIATION CAN PREVENT ALL 3 TYPES OF CANCERALL 3 TYPES OF CANCER

The DermisThe Dermis

The DermisThe Dermis

The dermis lies below the epidermis and has 2 The dermis lies below the epidermis and has 2 main components:main components:

Papillary layerPapillary layer

Reticular layerReticular layer

PAPILLARY LAYERPAPILLARY LAYER

- consists of loose connective tissue that supports - consists of loose connective tissue that supports and nourishes the epidermisand nourishes the epidermis

- - contains capillaries and nerves supplying the contains capillaries and nerves supplying the surface of the skinsurface of the skin

RETICULAR LAYERRETICULAR LAYER

- deeper layer- deeper layer

- consists of interwoven meshwork of dense, - consists of interwoven meshwork of dense, irregular connective tissueirregular connective tissue

- - boundary between reticular and papillary layers boundary between reticular and papillary layers is indistinctis indistinct

- collagen fibers of reticular layer extend into the - collagen fibers of reticular layer extend into the subcutaneous layersubcutaneous layer

- - reticular layer provides support and attachment reticular layer provides support and attachment for dermis while allowing flexibilityfor dermis while allowing flexibility

OTHER DERMAL OTHER DERMAL COMPONENTSCOMPONENTS

The dermis contains all of the cells found in The dermis contains all of the cells found in connective tissue proper (macrophages, connective tissue proper (macrophages, fibroblasts, etc)fibroblasts, etc)

- accessory organs such as hair follicles and sweat - accessory organs such as hair follicles and sweat glands extend into the dermisglands extend into the dermis

- other systems communicate with the skin - other systems communicate with the skin through the dermisthrough the dermis

Ex: reticular and papillary layers contain blood Ex: reticular and papillary layers contain blood vessels, lymph vessels, and nerve fibersvessels, lymph vessels, and nerve fibers

- - blood vessels provide nutrients and blood vessels provide nutrients and oxygen, and remove COoxygen, and remove CO22 and wastes and wastes

- blood and lymph vessels help local - blood and lymph vessels help local tissues defend and repair themselves after tissues defend and repair themselves after injury or infectioninjury or infection

- nerve fibers control blood flow, adjust gland - nerve fibers control blood flow, adjust gland secretion rates, and monitor nerve receptorssecretion rates, and monitor nerve receptors

The Subcutaneous LayerThe Subcutaneous Layer

Subcutaneous FatSubcutaneous Fat

The dermis is connected to the subcutaneous The dermis is connected to the subcutaneous layer by an extensive network of connective layer by an extensive network of connective tissue fiberstissue fibers

- the subcutaneous layer is not actually part of - the subcutaneous layer is not actually part of the integument, but is important in stabilizing the integument, but is important in stabilizing position of the skin in relation to underlying position of the skin in relation to underlying tissuetissue

- this layer contains many fat cells (adipose) - this layer contains many fat cells (adipose)

- - these adipose cells provide infants and small these adipose cells provide infants and small children with a layer of “baby fat” which reduces children with a layer of “baby fat” which reduces heat loss, and acts as a shock absorber to prevent heat loss, and acts as a shock absorber to prevent injuryinjury

- as we age, we accumulate this fat in different places:- as we age, we accumulate this fat in different places:

* Men- around neck, upper arms, lower back, buttocks* Men- around neck, upper arms, lower back, buttocks

* Women- breasts, buttocks, hips, thighs* Women- breasts, buttocks, hips, thighs

* * Both accumulate in abdominal areaBoth accumulate in abdominal area

- the subcutaneous layer is very elastic, has large - the subcutaneous layer is very elastic, has large blood vessels, and contains no vital organsblood vessels, and contains no vital organs

Accessory StructuresAccessory Structures

HAIR FOLLICLESHAIR FOLLICLES

Hair covers the body almost everywhere EXCEPT:Hair covers the body almost everywhere EXCEPT:

Sides and soles of feetSides and soles of feet

PalmsPalms

Sides of fingers and toesSides of fingers and toes

LipsLips

STRUCTURE OF HAIRSTRUCTURE OF HAIR

- hair follicles project into the dermis and often - hair follicles project into the dermis and often into the subcutaneous layerinto the subcutaneous layer

- walls of each follicle contain all the cell layers - walls of each follicle contain all the cell layers found in epidermisfound in epidermis

- the epithelium at the base of a follicle - the epithelium at the base of a follicle surrounds the HAIR PAPILLA- surrounds the HAIR PAPILLA- a peg of a peg of connective tissue containing capillaries and connective tissue containing capillaries and nervesnerves

- hair is formed by the repeated divisions of - hair is formed by the repeated divisions of epithelial stem cells surrounding the papillaepithelial stem cells surrounding the papilla

- as daughter cells are pushed to the surface, the - as daughter cells are pushed to the surface, the hair lengthens and the cells become hair lengthens and the cells become keratinized and diekeratinized and die

- - the point at which this occurs marks the the point at which this occurs marks the boundary of the HAIR ROOT and HAIR boundary of the HAIR ROOT and HAIR SHAFTSHAFT

- hairs grow and are shed according to a - hairs grow and are shed according to a HAIR HAIR GROWTH CYCLEGROWTH CYCLE based on the activity of based on the activity of hair follicleshair follicles

- generally, a hair in the scalp grows from 2 to 5 - generally, a hair in the scalp grows from 2 to 5 years at a rate of about 0.3 mm per day, and years at a rate of about 0.3 mm per day, and then its follicle may become inactive for some then its follicle may become inactive for some timetime

- - when another growth cycle begins, the old when another growth cycle begins, the old hair is pushed toward the surface to be shedhair is pushed toward the surface to be shed

- differences in hair length between individuals - differences in hair length between individuals depends on variations in growth rate and in the depends on variations in growth rate and in the length of the hair growth cyclelength of the hair growth cycle

- other differences in hair appearance result from - other differences in hair appearance result from size of follicles and shape of hairssize of follicles and shape of hairs

FUNCTIONS OF HAIRFUNCTIONS OF HAIR

- there are approximately 5 million hairs on the - there are approximately 5 million hairs on the human bodyhuman body

- - the 100,000 hairs on the head protect the the 100,000 hairs on the head protect the scalp from UV light, cushion a light blow to scalp from UV light, cushion a light blow to the head, and insulate the skullthe head, and insulate the skull

- hairs guarding the entrance to the nostrils and ears, as - hairs guarding the entrance to the nostrils and ears, as well as the eyelashes, defend against entry of foreign well as the eyelashes, defend against entry of foreign particles and insectsparticles and insects

- each hair follicle as a sensory nerve associated with it - each hair follicle as a sensory nerve associated with it you can feel a single hair move : early warning you can feel a single hair move : early warning systemsystem

- smooth muscles called ARRECTOR PILI MUSCLES - smooth muscles called ARRECTOR PILI MUSCLES are connected to the hair follicleare connected to the hair follicle

- when stimulated, they pull on follicle and cause hair - when stimulated, they pull on follicle and cause hair to stand up- to stand up- “goose bumps”“goose bumps”

HAIR COLORHAIR COLOR

- hair color depends on differences in type and - hair color depends on differences in type and amount of pigment produced by melanocytes in amount of pigment produced by melanocytes in the papillathe papilla

- - color is genetically determinedcolor is genetically determined

- color may also be influenced by hormonal or - color may also be influenced by hormonal or environmental changesenvironmental changes

Ex: pigment production decreases with age, and Ex: pigment production decreases with age, and color of hair lightenscolor of hair lightens

- - white hair results from lack of white hair results from lack of pigment, and the presence of air bubbles in pigment, and the presence of air bubbles in the hair shaftthe hair shaft

- as number of white hairs increases, - as number of white hairs increases, individual’s color is described as GRAYindividual’s color is described as GRAY

- - on average, about 50 hairs are lost from the on average, about 50 hairs are lost from the head per dayhead per day

SEBACEOUS GLANDSSEBACEOUS GLANDS

Sebaceous glands are a type of exocrine gland Sebaceous glands are a type of exocrine gland that discharge a waxy secretion into hair that discharge a waxy secretion into hair follicles and onto the skinfollicles and onto the skin

- contraction of arrector pili muscles squeezes - contraction of arrector pili muscles squeezes the sebaceous glands, forcing the secretions the sebaceous glands, forcing the secretions into the hair follicles and onto the surrounding into the hair follicles and onto the surrounding skinskin

- - the secretion is called SEBUM- it lubricates the secretion is called SEBUM- it lubricates the hair and inhibits growth of bacteriathe hair and inhibits growth of bacteria

Sebaceous glands are very sensitive to changes Sebaceous glands are very sensitive to changes in concentrations of sex hormonesin concentrations of sex hormones

- secretions increase at puberty- secretions increase at puberty

- - an individual with large sebaceous glands an individual with large sebaceous glands may be prone to ACNEmay be prone to ACNE

- in acne, sebaceous glands become blocked and - in acne, sebaceous glands become blocked and secretions accumulate causing pimples to formsecretions accumulate causing pimples to form

SWEAT GLANDSSWEAT GLANDS

The skin contains 2 types of sweat glands:The skin contains 2 types of sweat glands:

Apocrine sweat glandsApocrine sweat glands

Merocrine sweat glandsMerocrine sweat glands

APOCRINE GLANDSAPOCRINE GLANDS

- - secrete their products into hair follicles in the secrete their products into hair follicles in the armpits, around the nipples, and in the groinarmpits, around the nipples, and in the groin

- at puberty, these glands begin discharging a sticky, - at puberty, these glands begin discharging a sticky, cloudy secretion that becomes odorous when broken cloudy secretion that becomes odorous when broken down by bacteriadown by bacteria

- - antiperspirant works by contracting the antiperspirant works by contracting the sweat gland openings and decreasing the sweat gland openings and decreasing the quantity of secretionsquantity of secretions

MEROCRINE GLANDSMEROCRINE GLANDS

- far more numerous than apocrine glands- far more numerous than apocrine glands

- the skin of an adult contains 2-5 million - the skin of an adult contains 2-5 million merocrine glandsmerocrine glands

- - palms and soles have the highest numberpalms and soles have the highest number

- merocrine glands are coiled tubular glands that - merocrine glands are coiled tubular glands that discharge their secretions directly onto the surface discharge their secretions directly onto the surface of the skinof the skin

- - secretions are called PERSPIRATION- cool the secretions are called PERSPIRATION- cool the surface of the skin and reduce body temperaturesurface of the skin and reduce body temperature

When a person sweats in the hot sun, all When a person sweats in the hot sun, all merocrine glands are working together:merocrine glands are working together:

- blood vessels beneath the epidermis are flushed - blood vessels beneath the epidermis are flushed with blood- skin becomes redwith blood- skin becomes red

- - skin surface is warm and wet, and as the skin surface is warm and wet, and as the moisture evaporates, the skin coolsmoisture evaporates, the skin cools

- if body temperature falls too low, perspiration - if body temperature falls too low, perspiration stops, blood flow to the skin decreases, and the stops, blood flow to the skin decreases, and the cool, dry surfaces release little heat to the cool, dry surfaces release little heat to the environmentenvironment

SWEAT IS 99% WATERSWEAT IS 99% WATER

- but also contains salts, organic nutrients, and - but also contains salts, organic nutrients, and waste products such as ureawaste products such as urea

- - is what gives sweat a salty tasteis what gives sweat a salty taste

- when all merocrine glands are working together, - when all merocrine glands are working together, perspiration can exceed 1 gallon per hourperspiration can exceed 1 gallon per hour

- you must drink fluids to replenish this loss- you must drink fluids to replenish this loss

OTHER TYPES OF SWEAT GLANDS:OTHER TYPES OF SWEAT GLANDS:

- mammary glands produce milk- mammary glands produce milk

- - ceruminous glands in the ear produce ear waxceruminous glands in the ear produce ear wax

NAILSNAILS

Nails form on dorsal surface of fingers and toes, Nails form on dorsal surface of fingers and toes, and protect the exposed tips and help limit and protect the exposed tips and help limit their distortion when they are subjected to their distortion when they are subjected to mechanical stressmechanical stress

STRUCTURESTRUCTURE

- visible NAIL BODY made up of a mass of - visible NAIL BODY made up of a mass of dead, keratinized cellsdead, keratinized cells

- - it extends below the surrounding epitheliumit extends below the surrounding epithelium

- nail body covers an area of epidermis called the - nail body covers an area of epidermis called the NAIL BEDNAIL BED

- nail production occurs at the NAIL ROOT- - nail production occurs at the NAIL ROOT- an an epithelial fold that you cannot see from the epithelial fold that you cannot see from the surfacesurface

- a portion of the stratum corneum extends over the - a portion of the stratum corneum extends over the exposed nail nearest the root, forming the exposed nail nearest the root, forming the CUTICLECUTICLE

- underlying blood vessels give nails their pink color- underlying blood vessels give nails their pink color

- vessels may be obscured near the root, vessels may be obscured near the root, leaving a pale crescent known as the leaving a pale crescent known as the LUNULALUNULA

- nail structurenail structure

CONTROL OF CONTROL OF HOMEOSTASISHOMEOSTASIS

The integumentary system can respond directly The integumentary system can respond directly and indirectly to many local influences or and indirectly to many local influences or stimulistimuli

Ex: when skin is subjected to mechanical Ex: when skin is subjected to mechanical stresses, stem cells in the stratum stresses, stem cells in the stratum germinativum divide more rapidly to increase germinativum divide more rapidly to increase the thickness of the epithelium the thickness of the epithelium CALLUSES FORMCALLUSES FORM

INJURY AND REPAIRINJURY AND REPAIR

Skin can regenerate because stem cells are present Skin can regenerate because stem cells are present in epithelial and connective tissue componentsin epithelial and connective tissue components

- speed and effectiveness of skin repair depends - speed and effectiveness of skin repair depends on the type of woundon the type of wound

* * an INCISION (slender, straight cut) may an INCISION (slender, straight cut) may heal quicklyheal quickly

* * an ABRASION (scrape) may take longer to an ABRASION (scrape) may take longer to heal because it involves a greater areaheal because it involves a greater area

4 STAGES OF SKIN 4 STAGES OF SKIN REGENERATIONREGENERATION

1. When damage extends though epidermis and 1. When damage extends though epidermis and into the dermis, bleeding occursinto the dermis, bleeding occurs

2. 2. Blood clot or SCAB that forms temporarily Blood clot or SCAB that forms temporarily restricts the entry of additional restricts the entry of additional microorganismsmicroorganisms

- clot is made up of protein called FIBRIN- clot is made up of protein called FIBRIN

- cells of stratum germinativum rapidly divide and - cells of stratum germinativum rapidly divide and migrate along sides of the wound to replace migrate along sides of the wound to replace missing epidermal cellsmissing epidermal cells

- - phagocytes patrol damaged area and clear phagocytes patrol damaged area and clear away debris and pathogensaway debris and pathogens

3. Dermal repairs must occur before epithelial 3. Dermal repairs must occur before epithelial cells can cover the surfacecells can cover the surface

- fibroblasts and connective tissue stem cells - fibroblasts and connective tissue stem cells divide to produce mobile cells that invade divide to produce mobile cells that invade deeper areas of injurydeeper areas of injury

- capillaries follow the fibroblasts, providing a - capillaries follow the fibroblasts, providing a circulatory supplycirculatory supply

- combination of blood clots, fibroblasts, and - combination of blood clots, fibroblasts, and capillary network is called GRANULATION capillary network is called GRANULATION TISSUETISSUE

- - over time, the clot dissolves and number of over time, the clot dissolves and number of capillaries decreasescapillaries decreases

- fibroblast activity leads to formation of - fibroblast activity leads to formation of collagen fibers and ground substancecollagen fibers and ground substance

4. Scar tissue is formed4. Scar tissue is formed

- dermis will contain many collagen fibers and - dermis will contain many collagen fibers and few blood vesselsfew blood vessels

- - damaged hair follicles, glands, muscle cells, damaged hair follicles, glands, muscle cells, and nerves are seldom repairedand nerves are seldom repaired

BURNSBURNSBurns result from exposure of skin to heat, radiation, Burns result from exposure of skin to heat, radiation,

electrical shock, or strong chemical agentselectrical shock, or strong chemical agents

- severity reflects depth of penetration and total area - severity reflects depth of penetration and total area affected affected

FIRST-DEGREE BURNFIRST-DEGREE BURN

- - superficial cells of epithelium are killedsuperficial cells of epithelium are killed

- deeper areas of the epidermis and papillary dermis - deeper areas of the epidermis and papillary dermis are injuredare injured

- - area appears inflamed and is tenderarea appears inflamed and is tender

SECOND-DEGREE BURNSECOND-DEGREE BURN

- - superficial and deeper cells of epidermis are superficial and deeper cells of epidermis are killed; dermis may be affectedkilled; dermis may be affected

- reticular layer of epidermis may be injured, but - reticular layer of epidermis may be injured, but most accessory structures are unaffectedmost accessory structures are unaffected

- blisters are present; very painful- blisters are present; very painful

THIRD-DEGREE BURNTHIRD-DEGREE BURN

- all epidermal and dermal cells are killed- all epidermal and dermal cells are killed

- subcutaneous layer and deeper tissues and - subcutaneous layer and deeper tissues and organs are injuredorgans are injured

- - skin is charred; individual has no sensation skin is charred; individual has no sensation at allat all

AGINGAGING

SOME CHANGES THAT OCCUR WITH SOME CHANGES THAT OCCUR WITH AGING:AGING:

1. Skin injuries and infections become more 1. Skin injuries and infections become more common- common- epidermis thinsepidermis thins

2. Sensitivity of immune system reduced- 2. Sensitivity of immune system reduced- immune cells are decreasing in numberimmune cells are decreasing in number

3. Muscles become weaker, bone strength 3. Muscles become weaker, bone strength decreases- decline in vitamin Ddecreases- decline in vitamin D33 production production

4. Sensitivity to sun exposure increases- 4. Sensitivity to sun exposure increases- less less melanin producedmelanin produced

5. Skin becomes dry and scaly- 5. Skin becomes dry and scaly- sebum and sebum and perspiration production decreasesperspiration production decreases

6. Hair thins and color changes- follicles stop 6. Hair thins and color changes- follicles stop functioning; again decreased melanin productionfunctioning; again decreased melanin production

7. Sagging and wrinkling of skin- 7. Sagging and wrinkling of skin- dermis becomes dermis becomes thinner and elastic fiber network decreasesthinner and elastic fiber network decreases

8. Ability to lose heat decreases- blood supply to 8. Ability to lose heat decreases- blood supply to dermis is reduced; sweat glands become less dermis is reduced; sweat glands become less activeactive

- - more prone to overheatingmore prone to overheating

9. Skin repairs slowly9. Skin repairs slowly