The IntegumentaryThe IntegumentarySystemSystem

Skin = Integument = Cutaneous Skin = Integument = Cutaneous MembraneMembrane

Seven Functions of the Seven Functions of the skin…skin…

1.1. Protective coveringProtective covering2.2. Regulates body Regulates body

temperaturetemperature3.3. Manufactures Vitamin Manufactures Vitamin

DD4.4. Sensory FunctionSensory Function5.5. Temporary storage of Temporary storage of

fat, glucose, water and fat, glucose, water and saltssalts

6.6. Screens out harmful Screens out harmful ultraviolet radiationultraviolet radiation

7.7. Absorbs certain drugsAbsorbs certain drugs

Structure of the SkinStructure of the Skin

Epidermis Epidermis Outermost covering Outermost covering Epithelial cellsEpithelial cells AvascularAvascular

DermisDermis True skin True skin Connective tissueConnective tissue VascularVascular

EpidermisEpidermis 2 (of 3) 2 (of 3)

epidermal layers epidermal layers are:are:

Stratum corneumStratum corneum Stratum Stratum

germinativumgerminativum

Stratum CorneumStratum Corneum Outer most layer.Outer most layer. In cells, cytoplasm In cells, cytoplasm

replaced by Keratin-replaced by Keratin-making them making them waterproof.waterproof.

Flat and scale-like Flat and scale-like cells that flake off.cells that flake off.

First line of defense First line of defense against surface against surface bacteria.bacteria.

Thickest on palms of Thickest on palms of hands, soles of feet.hands, soles of feet.

Stratum GerminativumStratum Germinativum Innermost epidermal Innermost epidermal

layer.layer. Reproductive layer- cells Reproductive layer- cells

form and push their way form and push their way up, become keratinized, up, become keratinized, and replace the top and replace the top layer.layer.

Contains Contains MELANOCYTES cells MELANOCYTES cells that contain a pigment = that contain a pigment = MELANINMELANIN

Black, brown, or has Black, brown, or has a yellow tint-a yellow tint-depending on racial depending on racial origin.origin.

The more melanin, The more melanin, the darker the skin.the darker the skin.

Caucasians don’t Caucasians don’t have much melanin have much melanin in their melanocytesin their melanocytes

Freckles = patches of Freckles = patches of melaninmelanin

Albinism = no Albinism = no melaninmelanin

Melanin

TanningTanning Sunlight stimulates Sunlight stimulates

melanocytes to make melanocytes to make more melaninmore melanin

Tanning produced by Tanning produced by UV raysUV rays

Prolonged Prolonged exposure may lead to exposure may lead to skin cancer!skin cancer!

PapillaePapillae Ridges in stratum Ridges in stratum

germinativum that arise germinativum that arise from dermisfrom dermis

Create permanent Create permanent ridges in fingers, palms, ridges in fingers, palms, and soles of feetand soles of feet

These “friction ridges” These “friction ridges” help with griphelp with grip

Cause “fingerprints”Cause “fingerprints”

DermisDermis Thicker inner layer that contains:Thicker inner layer that contains: Connective tissue Connective tissue □□ Hair folliclesHair follicles Blood pressureBlood pressure □ □ Oil and sweat glandsOil and sweat glands Nerve endingsNerve endings □ □ Fat cellsFat cells MusclesMuscles

Nerve Receptors in Nerve Receptors in DermisDermis

Sensory nerves – Sensory nerves – heat, cold, touch, heat, cold, touch, pain and pressurepain and pressure

Touch receptors Touch receptors close to the surfaceclose to the surface

Pressure receptors Pressure receptors are deeperare deeper

Subcutaneous Layer- Subcutaneous Layer- Adipose tissueAdipose tissue

Lies under the Lies under the dermis (not really dermis (not really part of integumentary part of integumentary system).system).

Made up of loose. Made up of loose. connective tissue.connective tissue.

Contains half of the Contains half of the body’s stored fat.body’s stored fat.

Appendages of the SkinAppendages of the SkinHAIRHAIR

Almost everywhere on the Almost everywhere on the bodybody

Length, thickness, type and Length, thickness, type and color varies.color varies.

Outer layer = CORTEXOuter layer = CORTEX Inner layer = MEDULLAInner layer = MEDULLA Part under the skin = ROOTPart under the skin = ROOT Part outside the skin = Part outside the skin =

SHAFTSHAFT FOLLICLE = pocket in FOLLICLE = pocket in

epidermis, hair inside.epidermis, hair inside. PAPILLA = tuft of tissue in PAPILLA = tuft of tissue in

root, contains, capillaries.root, contains, capillaries.

Arrector Pili MuscleArrector Pili Muscle APM = smooth muscle APM = smooth muscle

attached to follicle. How attached to follicle. How does this muscle cause does this muscle cause goose bumps?goose bumps?

NailsNails Nail is formed in the nail Nail is formed in the nail

bed or MATRIX.bed or MATRIX. Epidermal cells fused Epidermal cells fused

together and fill with together and fill with keratin.keratin.

Sweat GlandsSweat Glands Perspiration is 99% water.Perspiration is 99% water. SUDORIFEROUS GLANDS.SUDORIFEROUS GLANDS. Distributed over the entire Distributed over the entire

skin surface.skin surface. Large numbers under the Large numbers under the

arms, palms of hands, soles arms, palms of hands, soles of feet and forehead.of feet and forehead.

Duct extends to form a pore Duct extends to form a pore in the skin, perspiration in the skin, perspiration excreted through the pores.excreted through the pores.

May be activated by heat, May be activated by heat, pain, fever and nervousness.pain, fever and nervousness.

Average fluid loss in 500 ml Average fluid loss in 500 ml per day.per day.

Sebaceous GlandsSebaceous Glands Secret Oil (SEBUM) Secret Oil (SEBUM)

that protects and that protects and lubricates the skin.lubricates the skin.

Skin and MicroorganismsSkin and Microorganisms Intact skin = best protection against Intact skin = best protection against

pathogens, toxins and water loss.pathogens, toxins and water loss. Skin generally too dry for microbial growth – Skin generally too dry for microbial growth –

they do grow in moist areas.they do grow in moist areas. Most skin bacteria associated with hair follicles Most skin bacteria associated with hair follicles

or sweat glands.or sweat glands. Underarm perspiration odor caused by Underarm perspiration odor caused by

bacteria and perspiration.bacteria and perspiration.

THE BEST WAY TO PREVENT THE SPREAD OF DISEASE IS BY HAND

WASHING!