INTEGUMENTARY SYSTEM

The skin (including sweat and oil glands), hair and nails

Integumentary System

Integument = coveringIncludes

Skin including sweat and oil glandsHairNails

Integumentary System Functions

1. Protection—protects underlying tissues and organs

Three types of barriers Chemical barrier—skin secretions, melanin (protects from

sun), acid mantle of skin decreases bacterial growth

(sebum kills bacteria) Physical or mechanical barrier—continuous surface of skin

(hard-fairly impermeable to disease) Biological barrier—Langerhan’s cells and phagocytes (all

work against disease)

Functions continued

2. Excretion—excrete salts, H2O, organic wastes through sweat

3. Body temperature regulation If air temp. is cold, then blood vessels in

dermis constrict which reduces heat loss through skin

If body temp. is hot, then blood vessels in dermis dilate bringing blood to skin surface where it is cooled

4. Touch reception- nerves in the dermis give us lots of info about our environment- touch, pressure pain, hot and cold

5. Vitamin D production- when skin is exposed to UV radiation it makes vitamin D

Regions

1. EpidermisSurface—many layers of epithelial

cellsFunction—protection

2. DermisUnder epidermis—thicker layermost of skin is dermisConnective tissue with blood vessels

3. Subcutaneous layer (hypodermis or superficial fascia)

Loose (fatty) connective tissueConnects skin to underlying organs

Epidermis Surface of skin Stratified squamous epithelium 4 cell types:

1. Keratinocytes—most common, make keratin(protein that makes skin strong, flexible and water resistant

Keratin is the basic component of hair, calluses and nails

When keratinocytes reach the skin surface, they’re dead cells which get worn off

Totally new epidermis every 35-45 days!

Epidermis

4 types of cells (cont.)2. Merkel’s cells- touch reception3. Melanocytes- produce the pigment

melanin4. Langerhan’s cells- part of body’s defense

against disease

Strata of the EpidermisStratum (singular) = layer 5 layers starting with the deepest

1. Stratum germinativum (stratum basale)—attached to basement membrane, cells are specialized for division. One cell layer thick.

2. Stratum spinosum (spiny layer)—several cell layers thick, spiny projections hold cells together

3. Stratum granulosum (grainy layer)—2 or 3 layers of flattened cells, keratin formation begins here

Strata of the Epidermis

4. Stratum lucidum (clear layer)—found in thick skin (palms and soles)cells flattened and densely packed

5. Stratum corneum (cornu = horn)—20-30 cell layers thick. Dead cells filled with keratin (organelles die as keratin fills cells). Lets skin surface be a protective ‘overcoat’ for the body

Dermis

Strong, flexible, connective tissue region of the skin with lots of nerve fibers, blood vessels, lymphatic vessels

Dermis

2 layers:1. Papillary—loose connective tissue

with dermal papillae that push into the epidermis. Patterns created by dermal papillae create fingerprints and line patterns on feet.

Dermis2. Reticular—dense irregular connective

tissue can tolerate stress from many directions because fibers run

in many directions.Lines of cleavage bundles of interlocking

collagen fibers that form patterns: surgical lines are often made parallel to lines of cleavage so that skin gapes less, heals more quickly, has less obvious scarring

Dermis (continued)

Flexure lines—folds in skin that allow joint movement

Stretch marks—tears in dermis caused by excessive skin stretching. Silvery scars = striae

Stratum Germinativum

Stratum corneum

Stratum lucidum

Stratum granulosum

Stratum spinosum

Subcutaneous layer

Sweat gland

Dermis

Adipose tissuePacinian corpuscle

Pore

Meisner’s corpuscle

Hair shaft

Dermal papillae

Sebaceous gland

Arrector pili muscle

Hair follicle

Hair root

Vein

Artery

Skin Color (3 Pigments)

1. Melanin—yellow to orange to brown made by melanocytes and transferred into

keratinocytes (keratin cells) Skin color varies by the amount and kind of

melanin made NOT by number of melanocytes(everyone has the same number of melanocytes)

Black and brown skinned people make more and darker melanin than lighter skinned people

Freckles and dark moles show local accumulations of melanin

Skin Color (3 Pigments)

Sun exposure leads to a build up of melanin providing some protection from the sun

Excessive sun exposure damages skin (elastic fibers clump leading to leathery, wrinkled skin and damage to the immune system) and can change DNA in cells leading to skin cancer

Melanin is a natural sunscreen Some antibiotics and antihistamines increase the

skin’s sensitivity to the sun-> rashes, blisters and skin peeling

Skin Color (3 Pigments) continued

2. Carotene—yellow/orange pigment Found in stratum corneum and subcutaneous

adipose tissue Shows most in palms and soles Found in fruits and vegetables Asian skin color is the result of a combination of

carotene and melanin

Carotene and keratin sound alike- what’s the difference?

3. Hemoglobin—red pigment from well oxygenated blood

Shows in pinkish color of caucasians (transparent epidermis) so hemoglobin from the capillaries in the dermis shows through

Too little oxygen causes skin to look blue (cyanosis). Can be seen in mucous membranes and nail beds of dark skinned people.

This can be caused by heart failure and severe respiratory disorders.

Skin Color Changes

Changes can be caused by emotional states and/or disease

Erythema—redness (embarrassment, fever) Pallor—paleness (fear, anemia) Jaundice—yellowing (liver disease) Bronzing—metallic appearance (Addison’s

disease) Bruises—blood escapes from vessels and

clots in tissues (hematoma). May be result of too little vitamin C or a bleeding disorder.

Hair Structure

Shape of shaft determines whether hair is curly or straight

Flat shaft=curlyOval shaft=wavyRound shaft= straight

3 layers of hair

Medulla

Cortex

Cuticle

Accessory Structures

Hair and hair folliclesFunctions of hair:

Protects head-from sun, heat

loss, and physical traumaShields eyes (lashes)Helps keep dust and

particles out of respiratory tract (nose hairs)

Hair Structure

Produced and contained in hair follicleMade of keratinShaft—part of hair above skin surfaceRoot—part of hair beneath skin surface

Hair Color

Melanocytes at base of hair send melanin into cells of cortex—combinations of yellow, brown & black melanin produce all hair colors

White or gray hair caused by decreased melanin production causing air bubbles to replace melanin in the hair shaft.

Cuticle

Cortex

Medulla

Melanocyte

Bulb

Hair Growth

Growing part of hair is at the root (in the bulb)Hair follicles begin deep in the dermis,

sometimes even in the subcutaneous layerOther structures connected with hair:

Nerve endings around bulbSebaceous (oil) glands lubricate hairArrector pili muscles--smooth muscle in dermis

Pull on hair follicle to make it stand up—goose bumps

Activated by cold, fright, or other strong emotion

Hair Growth (continued)

100,000 hairs in scalp, 30,000 in beardWhere on your body do you have no

hairs?3 types

Vellus—fine body hair of women and kidsTerminal—coarser, longer hair of scalp,

eyebrows, pubic and axillary areas as well as face and chest of men

Intermediate—all hair that doesn’t fit into other categories

Hair Growth (continued)

Nutrition and hormones affect hair growthPoor nutrition (esp. low

protein) Increased blood flow Testosterone Other factors that reduce hair growth:

high fever, surgery, emotional trauma, drugs

Hirsutism

Hair Growth

Hirsutism- excessive hair growth especially male pattern hair growth in women (often caused by adrenal gland tumor)

Hair Growth (continued)

Growth averages 1.5-2.2 mm per week Growth is fastest from teens – age 40 Hair thins with age because hairs are not

replaced as fast as they’re lost Growth cycle—active phase followed by

resting (inactive or dormant) phase Scalp follicles active for years, then inactive for

a few months (shed 50-90 a day) Eyebrow follicles active for 3-4 months Alopecia = baldness

Hair Growth

Alopecia=baldnessUsually starts at anterior hairline and

progresses posteriorlyTerminal hairs are replaced by vellus hairsMale patterned baldness- hereditary, sex-

linked. Growth cycles become super shortMedicine or hair transplant

Accessory StructuresNailsSimilar in structure to

hoof or claw in animalsHave free edge (visible) and root

(beneath skin)Pink because of blood supply in dermisStructure:

Lunula—white crescent at baseCuticle—thickened fold of skin at baseNail bed—stratum germinativum under

entire nail

Accessory StructuresSudoriferous Glands Sudoriferous Glands = Sweat Glands (2 types) 3 million over body EXCEPT: lips, nipples and

parts of external genitalia 1. Eccrine (merocrine) sweat glands

Most abundant type especially on palms, soles and forehead

Ducts go to pores on skin surface Secretion = sweat—99% water with salts and

wastes. Function: maintain body temp.

Sudoriferous Glands (continued)

2. Apocrine sweat glands Found mostly in axillae and genital-rectal areas Ducts end in hair follicles Apocrine sweat has same elements as eccrine

sweat plus fatty acids and proteins. Bacterial action on fatty acids and proteins is what

creates odor Begin to function at puberty.

Ceruminous glands—specialized apocrine glands that produce cerumin (ear wax)in the ear canal

Accessory StructuresSebaceous Glands

Sebaceous Glands = Oil Glands Found all over body except palms and soles Larger on face, neck and upper chest Sebum = oily secretion—usually travels

through duct to hair follicle, sometimes to pore on skin surface

Functions—sebumSoftens and lubricates hair and skinPrevents water loss from skinKills bacteria

Sebaceous Glands (continued)

Sex hormones cause sebaceous glands to become active at puberty

Clinical terms:Whitehead—blocked sebaceous glandBlackhead—sebum dries and darkensAcne—inflammation of sebaceous gland

usually due to bacterial infectionSeborrhea—over activity of sebaceous

glands. Causes oily scales that come off.

Skin Disorders

Albinism—(albino) melanocytes can’t make melanin Absence of pigmentation in skin, hair, eyes.

Athlete’s foot—fungus infection leads to itchy, red, peeling skin between toes

Boils—inflammation of hair follicles and sebaceous glands (cause: bacterial infection)

Cold sores—herpes virus infection. Causes blisters filled with fluid around lips and mouth

Contact dermatitis—caused by exposure to chemicals that create allergic response

Albino & Athletes Foot

Boils & Cold Sores

Contact Dermatitis & Decubitus Ulcer

Skin Disorders (continued) Decubitus ulcers—bed sores/pressure sores Impetigo—contagious rash Mongolian spots—bruised looking area at sacrum

—birth mark Psoriasis—chronic, hereditary condition.

Reddened spot covered with scales. Vitiligo—loss of pigment in patches of skin Genital Warts—caused by

HPV

Burns

Tissue damage caused by heat, electricity, chemicals, radiation

Burns are a major cause of death for those <40

Burns

Immediate threat to life—fluid lossFluids contain proteins and electrolytes,

fluid loss->dehydration and electrolyte imbalance->kidney failure and decreased blood circulation

Lost Fluids need to be replaced immediatelyNutrient needs are very high in burn

patients.

Burns

After immediate crisis—infection is biggest threat to lifeBarrier destroyed Immune system function decreases

Burns Only epidermis is

damaged—redness, swelling, pain. Heal in

2-3 days Epidermis and upper part

of dermis—1st degree S&S plus blisters. Skin regeneration. Heal 3-4 weeks if no infection.

Full thickness—burned areas look gray-white or black. Nerve endings destroyed(no pain). Skin grafting needed

Rule of Nines

Method for estimating how much of skin surface is burned.

Body is divided into areas that amount to 9% of skin surface.

Critical Burns

3 classes of critical burns30% of body has 2nd degree burnsMore than 10% has 3rd degree burnsAny 3rd degree burn on face, hands or

feet

Skin Cancer

3 types:1. Basal Cell Carcinoma

Starts in stratum germinativumMost common, least malignantFull cure with surgical removal in 99%Found on surfaces exposed to the sunStart as shiny, raised area and develop into

central ulcer surrounded by “pearly” edge

Skin Cancer Types (continued)

2. Squamous cell carcinomaStarts in stratum spinosumScaly reddened bump—grows rapidlySun exposureMetastasis rare

Skin Cancer Types (continued)

3. Malignant MelanomaCancer of melanocytesRarer than other types, but deadlyMelanomas often have irregular borders,

multiple colors, rapid growth, and bleed easily.

ABCD Rule for Melanoma Be on the look out and notify your doctor about any of the

following changes to a mole or birthmark:

A is for ASYMMETRY: One half of a mole or birthmark does not match the other.

B is for BORDER: The edges are irregular, ragged, notched, or blurred.

C is for COLOR: The color is not the same all over, but may have different shades of brown or black, sometimes with patches of red, white, or blue.

D is for DIAMETER: The area is larger than 6 millimeters (about ¼ inch -- the size of a pencil eraser) or is growing larger.

The most important warning sign for skin cancer is a spot on the skin that changes in size, shape, or color.

Development

Embryonic developmentBy 4th month—skin well formed5th and 6th month—lanugo7th month vellus hairs appearAt birth—vernix caseosa (produced by

sebaceous glandsNewborn skin thin and often covered by

milia (sebaceous secretion) on nose and cheeks—goes away by 3-4 weeks after birth

Development (continued)

AdolescenceSkin and hair oilerAcne usually goes away in early adulthoodSkin usually looks its best in 20s and 30s

DevelopmentOld Age

Changes caused by continued exposure over time Epidermal cells have slower mitosis—skin thins Sebaceous and sweat glands less active—skin gets drier

and itchy Collagen and elastic fibers fewer and stiffer Subcutaneous fat layer decreases leading to decreased

tolerance to cold Melanocytes less active—decreased protection from sun Light skinned, light haired people tend to show signs of

age sooner To reduce aging changes—decrease sun exposure, eat

well, get lots of fluids

Integumentary System Effect on other Systems

Entire skin is only as thick as a paper towel! When the skin is damaged almost every body

system reacts Each system gets something from the

integumentary system and gives something to the integumentary system.

What examples can you think of?