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Integumentary System

A & P

Charles C. Cook, MD

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Integumentary System

• Integument: An outer protective covering such as the skin.

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Integumentary System

• The skin together with certain accessory organs

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MEMBRANE

• Thin sheet-like structure

• Covers & protects body surfaces

• Lines cavities

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Membranes

• Lines the internal surfaces of hollow organs i.e. mouth, lungs, bladder

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4 MAJOR TYPES4 MAJOR TYPES OF OF

MEMBRANES MEMBRANES(see page 109)(see page 109)

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SEROUSSEROUS MUCOUSMUCOUS CUTANEOUSCUTANEOUS SYNOVIALSYNOVIAL

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Serous MembranesSerous Membranes Line cavities that lack Line cavities that lack

openings to outsideopenings to outside Secrete serous fluid Secrete serous fluid Two classificationsTwo classifications

–parietalparietal–visceralvisceral

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• When you hear parietal think wall or the surroundings.

• When you hear visceral think guts or organs.

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Parietal MembraneParietal MembraneLines the walls of Lines the walls of

cavities (examples: cavities (examples: parietal pleura, parietal pleura, parietal peritoneum)parietal peritoneum)

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Visceral MembraneVisceral MembraneCovers surface of Covers surface of

organs (ex. visceral organs (ex. visceral pleura, visceral pleura, visceral peritoneum)peritoneum)

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Visceral & Parietal Membranes

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Mucous MembranesMucous Membranes–Line cavities and Line cavities and tubes that open to tubes that open to the outside of the the outside of the body.body.

–Respiratory, GI, Respiratory, GI, Urinary and Reprod.Urinary and Reprod.

–Goblet cells secrete Goblet cells secrete mucusmucus

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Cutaneous Cutaneous MembraneMembrane–External body covering External body covering (skin)(skin)

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Synovial Synovial MembraneMembrane– Lines joint cavities of Lines joint cavities of

movable jointsmovable joints– Synovial fluidSynovial fluid

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Skin and It’s Skin and It’s TissuesTissues

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Composed of Composed of epithelium, epithelium, connective tissue; connective tissue; together w/certain together w/certain accessory organs accessory organs (glands, hair, nails & (glands, hair, nails & special receptors)special receptors)

SkinSkin

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INTEGUMENTARY SYSTEMINTEGUMENTARY SYSTEM

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ProtectionProtection Body temp. regulationBody temp. regulation Water loss reductionWater loss reduction Houses sensory receptorsHouses sensory receptors Vitamin D synthesisVitamin D synthesis ExcretionExcretion

Function of the Skin

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Protection• Protects underlying tissue

– Keratinization i.e. callus

• Bacterial/Antigen invasion– Acidic pH– Naturally occurring antibiotic– Langerhan’s cells—activate immune sys.– Macrophages

• Ultraviolet radiation

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Body temperature regulation

• Radiation – thermal energy moving from warmer to cooler environment.

• Conduction – objects in contact with one another transferring heat from warmer to cooler environment.

• Convection – warm air rises and cool air falls.

• Evaporation – sweat absorbs heat from body then heat lost in evaporation.

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Body temperature regulation

• Vasodilation—blood vessels increase in diameter

• Vasoconstriction—blood vessels decrease in diameter

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Body temperature regulation

• Body temperature too high– Vasodilation– Increase sweating

• Body temperature too low– Vasoconstriction– Decreased sweating

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Water Loss Reduction

• Average water loss due to sweat is 300-500 ml/day (depends on environment and activity level)

• Stratum corneum provides barrier against excessive water loss

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Houses Sensory Receptors

• Sensory nerve endings that detect stimuli related to temperature, touch, pressure and pain

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Vitamin D Synthesis

• Vitamin D needed to absorb calcium in the gut.

• Modified cholesterol molecules in the skin are activated by UV light and form Vitamin D.

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Excretion

• Sweat– Primarily water– Small amounts of urea, uric acid, ammonia– pH is acidic—Why?

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The skin is composed of The skin is composed of 3 3 distinct layers:*distinct layers:*– EpidermisEpidermis– DermisDermis– Subcutaneous Subcutaneous

(hypodermis or SubQ)(hypodermis or SubQ)

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Epidermis- Outer Epidermis- Outer layerlayer –protective function: protective function:

water losswater lossmechanical injurymechanical injuryharmful chemicalsharmful chemicalsharmful microorganismsharmful microorganisms

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The epidermis is The epidermis is composed of composed of stratified squamous stratified squamous epithelial tissueepithelial tissue

Epidermis

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OutermostOutermost layer dead layer dead cells,cells, innermostinnermost livingliving

Lacks blood vesselsLacks blood vesselsRemember this for nails Remember this for nails

and hairand hair

Epidermis

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The deepest layerThe deepest layer contains cells contains cells undergoing mitosisundergoing mitosis–nourished by dermal nourished by dermal blood vesselsblood vessels

Stratum Basale

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Stratum Corneum

• Outermost layer of the epidermis

• Epidermal cells that have undergone keratinization

• Skin cells migrate toward the surface

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During keratinization the During keratinization the cytoplasm develops cytoplasm develops tough, fibrous, tough, fibrous, waterproof protein called waterproof protein called keratinkeratin and the cells die and the cells die (2-4 wks)(2-4 wks)

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Produce melanin (all Produce melanin (all humans have about the humans have about the same number same number of of melanocytes, regardless melanocytes, regardless of racial origin)of racial origin)

Protection from U.V. Protection from U.V. lightlight

Melanocytes

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Melanocytes

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Skin colorSkin color– largely due to melanin largely due to melanin

and size of the pigment and size of the pigment granulesgranules

– environ., physiological, environ., physiological, and genetic factorsand genetic factors

– Oxygen depleted blood, Oxygen depleted blood, darker color and gives darker color and gives off a bluish hue off a bluish hue (cyanosis)(cyanosis)

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Fibrous connective tissueFibrous connective tissue Living throughout Living throughout Blood vessels nourish and Blood vessels nourish and

regulate temp. regulate temp. Nerve fibers scattered Nerve fibers scattered

throughout the dermisthroughout the dermis

Dermis- Thick Inner layerDermis- Thick Inner layer

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Dermis

Contained in the dermis

1. Nerves

2. Hair follicles

3. Sweat glands

4. Sebaceous glands

5. Blood vessels

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Subcutaneous Subcutaneous LayerLayer

(hypodermis)*(hypodermis)*

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Loose connective tissue, Loose connective tissue, adipose tissueadipose tissue

Conserves heat, stores Conserves heat, stores energyenergy

Blood vessels supply Blood vessels supply adipose tissueadipose tissue

Resist heat exchangeResist heat exchange

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ACCESSORY ORGANSACCESSORY ORGANS

• Hair

• Nails

• Oil glands

• Sweat glands

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Hair

• All body surfaces except palms, soles,lips, nipples, and some of the external repro. organs

• Dead epidermal cells

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Develops from Develops from epidermal cells at base epidermal cells at base of hair follicleof hair follicle

Older cells pushed to Older cells pushed to the surface, keratinize the surface, keratinize and dieand die

Visible portion is called Visible portion is called the shaftthe shaft

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Arrector piliArrector pili muscle muscle contracts to contracts to straighten and raise straighten and raise hairhair

Hair color is Hair color is determined by determined by geneticsgenetics

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When Hair Goes Bad

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- rigid plates covering - rigid plates covering tips of digitstips of digits– produced by produced by

epidermal cells that epidermal cells that undergo undergo keratinizationkeratinization

– harder than the harder than the keratin produced in keratin produced in the rest of the skin the rest of the skin

Nails

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SebaceousSebaceous GlandsGlands

Generally associated Generally associated with hair follicleswith hair follicles

Secrete sebum, Secrete sebum, keeping skin and hair keeping skin and hair soft and pliablesoft and pliable

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SebumSebum composed of composed of fatty material and fatty material and cellular debriscellular debris

NoNo sebaceous glands sebaceous glands in in palms or solespalms or soles– responsible for acneresponsible for acne

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– consist of a coiled tubeconsist of a coiled tube– primarily water, but primarily water, but

contains salt and wastecontains salt and waste– two types: apocrine and two types: apocrine and

eccrineeccrine

SweatSweat (sudoriferous)(sudoriferous) glandsglands

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Apocrine glandsApocrine glands–respond to respond to emotional stressemotional stress

–begin to function begin to function at pubertyat puberty

–located in the located in the groin and armpitsgroin and armpits

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Eccrine sweat glandsEccrine sweat glands– respond to elevated body respond to elevated body

temperaturetemperature– environmental heat or environmental heat or

exerciseexercise NOTE: Hair follicles and NOTE: Hair follicles and

Sweat glands are lined Sweat glands are lined w/epidermal cellsw/epidermal cells

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Free Nerve Endings

• Common in epithelial tissues

• Distal part of the neuron

• Sensitive to tissue damage and pressure

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Meissner’s Corpuscles

• Masses of connective tissue cells

• Abundant in the hairless portions of the skin– Lips, palms, soles, external genitalia and

nipples

• Responds to light touch

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Pacinian Corpuscles

• Relatively large structures

• Composed of connective tissue fibers and cells

• In the deeper dermis and subcutaneous tissues, tendons and ligaments

• Respond to heavy pressure and associated with the sensation of deep pressure

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Body Temperature Body Temperature RegulationRegulation– Temp. above normal, Temp. above normal,

blood vessels dilate, blood vessels dilate, sudoriferous glands sudoriferous glands secretesecrete

– Temp. below normal, Temp. below normal, blood vessels constrict, blood vessels constrict, inactivityinactivity

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– Excessive heat loss Excessive heat loss causes skeletal causes skeletal muscles to contract muscles to contract involuntarilyinvoluntarily (shivering)**(shivering)**

– Circulatory and Circulatory and respiratory systems systems also help to control also help to control body temperature.body temperature.

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Langer’s Lines

• Tension lines in the skin

• Incisions made along these lines are under less tension when closed and therefore heal with better scar results

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Wound Healing

• Shallow wound – epithelial cells at the margin of the wound reproduce more rapidly to fill the gap.

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Wound Healing

• Wound extends into dermis or sub-q– Escaping blood forms clot– Fibroblasts migrate into area– Phagocytic cells engulf dead cells and debris– Damaged tissue is replaced and scab falls off

• Large open wounds –granulations form

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Wound Closure

• If edges can be approximated better end results occur (less infiltration of fibroblasts)

• Only clean wounds should be closed (primary intention)

• Dirty wounds should be debrided and irrigated with copious amounts of saline and possibly left open for 2-3 days (delayed closure)

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Wound Closure

• Bite wounds (especially human and cat bites) should not be closed primarily

• Severely contaminated wounds (blast wounds, perforated viscous, etc.) are often left open to granulate in (secondary intention)

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QUQUESTESTIOIONS?NS?? ?

NOW WHAT WAS NOW WHAT WAS HE TALKING HE TALKING ABOUT AGAIN?!?!?ABOUT AGAIN?!?!?

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Question

• List the protective properties of the skin.

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Answer

• Protection

• Body temp reg.

• Water loss reduction

• Houses sensory receptors

• Vitamin D synthesis

• Excretion

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Question

• Sudoriferous gland is another name for what?

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Answer

• A sweat gland.

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Question

• If all races have approximately the same number of melanocytes, what accounts for the difference in skin color?

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Answer

• Although all races have approximately the same number of melanocytes the amount of the pigment melanin in each melanocyte varies.

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Question

• True or false

• The mammary gland is a type of sweat gland.

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Answer

• True The mammary gland is a modified sweat gland that belongs to the integumentary system although it is frequently grouped with the reproductive system.

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Question

• The epidermis contains both _________ and ___________ cells.

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Answer

• Living and non-living

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Question

• In what layer of the skin will you find hair follicles, sweat glands and sebaceous glands?

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Answer

• Dermis

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Question

• Describe how the skin regulates body temperature.

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Answer

• Excess heat- vasodilatation and sweat production.

• Body temperature low – vasoconstriction to keep core warmer, sweat glands become inactive

• Excessive heat loss or hypothalamus dysfunction – shivering occurs

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Question

• Apocrine sweat glands respond to ______ ________ while eccrine sweat glands respond to _________ ______ ________.

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Answer

• Emotional stress; elevated body temperature

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Question

• What do epidermal skin development, nail growth and hair growth have in common?

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Answer

• Epidermal cells develop deeper where they are closer to nutrients; they slowly migrate to the surface slowly dying and becoming more compacted; they undergo keratinization and become skin, nails or hair.

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