Chapter 4Skin &

Body Membranes

2. Aids in heat regulation3. Aids in excretion of uric acid4. Synthesizes vitamin D

Skin Functions1.Protects deeper tissues

from:Mechanical damageChemical damageBacterial damageThermal damageUltraviolet radiationDesiccation

Integumentary SystemSkin (cutaneous membrane)Skin derivatives

-Sweat glands-Oil glands-Hairs-Nails

Skin StructureThe skin is composed of three layers:

1. Epidermis- (outer layer) composed of stratified squamous epithelium which is keratinized

2. Dermis- (middle layer) composed of dense irregular connective tissue

-accessory organs: hair follicles, eccrine and apocrine glands (sweat glands), sebaceous glands (oil glands), blood vessels, nerve endings, arrector pili muscles, and capillary beds.

3. Hypodermis – (lower layer or subcutaneous layer) composed of adipose tissue contains arteries, veins, and large nerves

Layer of Epidermis

Stratum basaleCells undergoing mitosisLies next to dermiscontains cells called melanocytes

Stratum spinosumStratum granulosumStratum lucidum

Occurs only in thick skin (soles of feet and palms of hands)

Stratum corneumShingle-like dead cells

Stratum basale

Stratum granulosum

Stratum spinosum

Stratum lucidum

Stratum corneum

Identify the layers of the thick skin tissue sample.

X - RayNQ

MelaninPigment produced by melanocytesMelanocytes are mostly in the stratum basaleAmount of melanin produced depends upon genetics and exposure to sunlight-"tanning effect"

Normal Skin Color DeterminantsMelanin

Yellow, brown or black pigmentsCarotene

Orange-yellow pigment from some vegetablesHemoglobin

Red coloring from blood cells in dermis capillariesOxygen content determines the extent of red coloring

Put the layers of the skin in order from outer most to inner most.

dermis

stratum corneum

epidermisstratum lucidum

stratum granulosumhypodermisstratum basale

stratum spinosum

Quanecia's Integument Rythym

DermisTwo layers

1. Papillary layerŸProjections called dermal papillae (responsible for fingerprints) ŸPain receptorsŸCapillary loops

2. Reticular layerŸBlood vesselsŸGlandsŸNerve receptors

Appendages of the SkinSebaceous glands

Produce oilLubricant for skinKills bacteria

Ducts that empty into hair folliclesGlands are activated at puberty

Sweat glands: produce sweatTwo types: a. Eccrine: produce watery sweat,

found all over body - empty out on the epidermis

surfaceb. Apocrine: produce sweat, fatty

substances, and protein - Located in the axillary and pubic

regions - Become active during puberty - body odor due to bacteria - empty into hair follicles.

Modified apocrine glands:Ceruminous glands: ear, produce

cerumen or ear wax Mammary glands: breasts, produce

and secrete milk

Function Helps dissipate excess heatExcretes waste productsAcidic nature inhibits bacteria growth

Hair AnatomyCentral medullaCortex surrounds medullaCuticle on outside of cortex

Appendages of the SkinHair

-Produced by hair bulb-Hard dead keratinized epithelial cells-Melanocytes provide pigment for hair color

Associated Hair StructuresHair follicleArrector pilli

Smooth muscleSebaceous glandSudoriforous gland

Appendages of the SkinNails

Scale-like modifications of the epidermisHeavily keratinizedStratum basale beneath the nail bed is responsible for growth

Lack of pigment makes them colorless

Nail StructuresFree edgeBodyRoot of nailEponychium – proximal nail fold that projects onto the nail body

LanulaCuticle

Body of nailNail matrixNail root Cuticle

Nail bedFree edgeBody of nail

Label the fingers!

Nerve receptors: The skin has receptors for pressure (Pacinian and Meissner’s corpuscles), pain, and temperature. Meissner’s corpuscles are located just below the surface of the epidermis and are sensitive to light pressure or touch, these are associated with “tickling sensations”.Pacinian Corpuscles are located deep in the dermis and are associated with strong touch and pressure.

Root hair plexus are associated with each hair follicle and is responsible for the pain when your hair is pulled.Free nerve endings are scattered throughout the dermis and are specialized for the reception of heat, cold, or pain.

Appendages of the Skin

Temperature Regulation

• Your skin acts similar to a radiator on a car to disseminate heat that is produced by cellular activity in your body and muscular contraction.

• This process is under the control of the hypothalamus in the brain.

• Negative feedback mechanism

Temperature Regulation• body temperature goes above the

set homeostatic value• the blood vessels in the dermis dilate and

increase blood supply to the capillary beds located there

• eccrine glands begin to secrete sweat which moves to the surface of your epidermis

• heat is transferred from the blood in your capillaries, through the dermis and epidermis, to the surface of the epidermis and is absorbed by the water in the sweat and vaporizes or evaporates it

• The blood has now lost heat and is at a lower temperature and returns to the inner body away form the surface to cool the inner body structures

Temperature Regulation• When the body’s temperature falls below the set

homeostatic value• The arterioles constrict, forcing blood toward the interior organs • The pili arrector muscles contract, generating heat, and raising the

hair trapping an insulating layer of air around the skin

Hair shaft

Meissner's corpuscle

Pacinian corpuscle

Sebaceous gland

arrector pili muscle

Hair follicle

Hair root

Eccrine sweat gland

Root hair plexus

Adipose tissue

vein

artery

Free nerve ending

Eccrine sweat gland

Sweat poreEpidermis

Dermis

Hypodermis

Label the diagram!

A, D

A, DE

HBA

H

B

G

Melanin

Keratin

TCorneum

ShaftDermis

CortexMedullaCuticle Cuticle

MedullaCortex

epidermisdermis

hypodermis

hair follicle

sebaceous gland

hair shaft

arrector pili

adipose

sweat gland

stratum corneum

dermal papillae

nerves

hair bulb

Skin Homeostatic ImbalancesInfections

1. Athletes footFungal infection

2. Boils and carbunclesBacterial infection

3. Cold soresViral

Infections and allergies4. Contact dermatitis

Exposures cause allergic reaction5. Impetigo

Bacterial infection6. Psoriasis

Cause is unknownTriggered by trauma, infection, stress

Diseases and Disorders of the SkinImmunological

• Acne vulgaris: Due to formation of sebum plugs (white heads or black heads) which block the sebaceous gland and often trap bacteria within the gland.

– Can become inflamed which can lead to the secondary infections of sweat gland or hair follicle forming pustules or pimples

Diseases and Disorders of the SkinImmunological

• Chicken pox: due to a viral infection (Herpes zoster) of the skin which affects the nerve ending

– results in the formation of blisters that itch

Diseases and Disorders of the SkinImmunological

• Tinea: Ring worm, Athlete’s foot, and Jock itch are all the result of a fungal infection of the skin.

– results in scaling, erythema (reddening), and occasional cracking of the skin that burns or itches

Diseases and Disorders of the SkinImmunological

• Warts: due to infection by the human papilloma virus.

– causes abnormal growth of the epidermal layer

– Normally warts are benign but some forms can transform and become malignant (cervical cancer)

– transmitted by direct contact from one person to another

Diseases and Disorders of the SkinImmunological

• Impetigo: caused by an infection of the epidermis by Staphlococcus or Streptococcus bacteria

– results in erythema, formation of weeping blisters, that form a yellow crusting on their surface

– highly contagious and common in children

Diseases and Disorders of the SkinImmunological

• Contact dermatitis: due to an allergic reaction with materials which the skin has made contact

– characterized by erythema, edema, blistering and scaling of the skin

– Itching is usually associated with the area affected

– Poison Ivy is an example of this disorder

Diseases and Disorders of the SkinImmunological

• MRSA infection is caused by Staphylococcus aureus bacteria — often called "staph." MRSA stands for methicillin-resistant Staphylococcus aureus (resistant to antibiotics)

– can be fatal. – Most MRSA infections occur in

hospitals or nursing homes and dialysis centers.

– community-associated MRSA: responsible for serious skin and soft tissue infections and for a serious form of pneumonia.

Matching1. Characterized by dry cracked skin with burning and itching, usually between the toes.

2. Caused by the human papillomavirus.3. A red itchy rash sometimes caused by poison ivy.

4. A bacterial infection that usually occurs in children, characterized by crusty or oozing blisters.

WartsImpetigo

Dermatitis

Tinea

MRSA

5. A serious staph infection.

Athlete's foot Dermatitis

Impetigo

AcneMRSA (boil)Psoriasis

Warts

Chicken poxHerpes

Boil

Skin Homeostatic Imbalances

BurnsTissue damage and cell death caused by heat, electricity, UV radiation, or chemicalsAssociated dangers

Dehydration & infection Electrolyte imbalance Circulatory shock

Rule of Nines

Determines the extent of burnsBody is divided into 11 areas-

-for quick estimationEach area represents about 9%

Severity of Burns• 1st Degree burns: – epidermis only – result in redness and swelling (edema)– Usually no scarring of tissue• 2nd Degree burns: – epidermis and dermis, some damage to

accessory organs– blistering but usually little scarring.• 3rd Degree burns: – epidermis, dermis, and hypodermis– destruction of dermal accessory organs, burn

is raw or blackened in appearance– Severe scarring occurs, long healing period,

usually involving skin grafting

Critical BurnsBurns are considered critical if:

Over 25% of body has second degree burnsOver 10% of the body has third degree burnsThere are third degree burns of the face, or feet

What degree of burn is shown in the pictures?

Skin Cancer

Cancer – abnormal cell massTwo types

BenignDoes not spread (encapsulated)

MalignantMetastasized (moves) to other parts of the body

Skin cancer is the most common type of cancer

Skin Cancer Types

Basal cell carcinomaLeast malignantMost common typeArises from statum basale

Squamous cell carcinomaMetastasizes to lymph nodesEarly removal allows a good chance of cure

Skin Cancer Types

Malignant melanomaMost deadly of skin cancersCancer of melanocytesMetastasizes rapidly to lymph and blood vesselsDetection uses ABCD rule

ABCD RuleA = Asymmetry

Two sides of pigmented mole do not matchB = Border irregularity

Borders of mole are not smoothC = Color

Different colors in pigmented areaD = Diameter

Spot is larger then 6 mm in diameter