THE INTEGUMENTARY SYSTEMThe skin and its accessory structures

FUNCTIONS OF THE INTEGUMENTARY SYSTEM

Protection Regulate body

temperature Cutaneous sensation Synthsize Vitamin D Blood storage Excretion of wastes

(sweat)

THE SKIN A large organ

composed of all 4 tissue types 22 square feet 1-2 mm thick Weight 10 lbs.

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VIDEO The Integumentary System (www.medc

omrn.com) (800) 877-1443.wmv

LAYERS OF SKINEpidermis The superficial portion of the skin Composed of epithelial tissueDermis The deeper layer of the skin Primarily composed of connective tissueHypodermis (subcutaneous

layer) Deep to the dermis Not a part of the skin Consists of areolar and adipose tissue Fat storage, area for blood vessel passage, and an area of pressure sensing nerve endings

OVERVIEW OF EPIDERMIS

Stratified squamous epithelium avascular (contains no blood vessels) 4 types of cells 5 distinct strata (layers) of cells

EPIDERMIS

DERMIS

FOUR PRINCIPLE CELLS OF EPIDERMISKeratinocytes Produce keratin

KERATIN protects skin and underlying tissue from heat, microbes, chemicals

Release lamellar granules which release a lipid waterproof sealantMelanocytes Produce pigment melanin

melanin contributes to skin color and absorbs damaging ultraviolet rays (UV rays)

Langerhans cells Phagocyte cells that participate in immune responseMerkel cells Sensory cells Function in the sensation of touch

5 LAYERS OF THE EPIDERMISFrom deepest to most

superficial (bottom to top) Stratum basale (also called stratum

germinativum) Stratum spinosum Stratum granulosum Stratum lucidum (only in palms and soles) Stratum corneum

STRATUM BASALE (basal layer) Deepest single layer of

epidermis Include all 4 cell types: merkel cells,

melanocytes, keratinocytes & stem

cells Cells divide repeatedly

(MITOSIS) When this portion of the epidermis is destroyed,

new skin cannot regenerate (even with a skin graft).

STRATUM SPINOSUM (prickly layer)

Provides strength and

flexibility to the skin

8 to 10 cell layers

STRATUM GRANULOSUM (granular layer)

Transition between the deeper, metabolically active

strata and the dead cells of the more superficial strata 3-5 layers of flat dying cells that show nuclear

degeneration Contain lamellar granules that release lipid that repels water Contain dark-staining keratohyalin granules keratohyalin converts into keratin

STRATUM LUCIDUM (clear layer)

Present only in the fingers tips, palms of the hands, and soles of the feet.

3 to 5layers of clear, flat, dead cells

Contains precursor of keratin

STRATUM CORNEUM (Horny layer) 25 to 30 layers of flat dead cells filled with keratin and

surrounded by lipids Continuously shed Barrier to light, heat, water, chemicals & bacteria Lamellar granules in this

layer make it water-repellent.

Where callus, an abnormal thickening of the epidermis, is formed

MNEUMONIC DEVICE B S G L C

Every Good Boy Does Fine.

Please Excuse My Dear Aunt

Sally.

King Philip, Come Out For Goodness

Sake!

SKIN STRUCTURE

Figure 4.4

MELANIN Pigment (melanin) produced by melanocytes Color is yellow to brown to black Melanocytes are mostly in the stratum

basale Amount of melanin produced depends upon

genetics and exposure to sunlight Skin with too much melanin is called

hyperpigmented skin. Skin with too little melanin is called

hypopigmented skin.

DERMIS Strong, flexible connective tissue Heavily embedded with collagen,

elastin, reticular fibers Binds the entire body together like a

body stocking. (Like an animal “hide”.) Richly supplied with nerve fibers, blood

vessels, and lymphatic vessels. Contain: hair follicles, oil & sweat

glands

DERMIS Two layers1. Papillary layer (thin, superficial

layer = 20%) Projections called dermal papillae

Pain receptors Capillary loops EPIDERMAL RIDGES form on palms of hands and soles of feet

increase friction and enhance gripping

Form FINGERPRINTS

2. RETICULAR LAYER (80% thickness) Contain; blood vessels, glands, nerve

receptors Bundles of collagen fibers form cleavage lines

(Appear as fine lines on the skin.) Surgery: incisions parallel, not perpendicular No skin gapes; heals faster

Collagen & Elastin: give skin resiliency, flexibility and bind to water to keep skin hydrated.

Flexure lines (deep folds) @ joints (wrists, fingers, soles, toes)

FINGERPRINTSThere are three basic fingerprint

patterns and seven subgroups.

FINGERPRINTS  A fingerprint is an impression of the friction

ridges found on the inner surface of a finger or a thumb. 

Friction ridges are also found on the palms of the hands and on the soles and toes of your feet. Fingerprints are formed while a baby is still in the womb. 

You cannot get rid of your fingerprints – you also cannot change them, unless you do something drastic such as chopping off a finger. 

FINGERPRINTS Every person’s fingerprint is unique. Not even

identical twins have the same fingerprints. No two fingerprints have ever been found to be identical. 

Secretions from the eccrine (sweat) glands can leave impressions on smooth surfaces, such as glass, plastic, and polished wood. 

A special type of powder is used to ‘lift’ fingerprints from such surfaces for purposes of identification. 

FINGERPRINTS A Frenchman, pioneered the use of physical

evidence to solve crimes. The date was 1812.  

Fingerprinting is the most commonly used forensic evidence worldwide. It is claimed to do better than DNA testing to identify murderers, rapists and other serious offenders, especially in countries where DNA testing is not widely used.

TATTOOS

TATTOOS

TATTOOS Tattooing is a permanent coloration of the skin

in which a foreign pigment is injected into the dermis.

When first injected into the skin, tattoo ink spreads from the puncture site to both the epidermis and the dermis. And as your tattoo heals, immune cells or phagocytes in the epidermis engulf the ink and epidermal cells flake off, carrying ink away.

The dermis also contains cells involved in immune responses and that recognize the tattoo ink as foreign. Tattoo ink is trapped in the dermis in a meshwork of fibroblast cells and collagen that form granular tissue.

If a tattoo is done properly, tattoo ink won't reach the hypodermis. As you get much older, the tattoo pigment may migrate deeper into the dermis (that's why your tattoo may fade a bit over time), but for the most part, it remains at the upper portion of the dermis, closer to the epidermis.

SKIN COLOR Melanin

Yellow, brown or black pigments Carotene

Orange-yellow pigment from some vegetables

Hemoglobin Red coloring from blood cells in dermis

capillaries Oxygen content determines the extent of

red coloring

HOMEOSTATIC IMBALANCES• Go to page 156 in your text.• Choose ONE homeostatic imbalance on

page. • Read about it.• Write a short summary in your

notebook, identifying the name, cause, and appearance (if listed).