UNIT 3: INTEGUMENTAR

Y SYSTEMChapter 5

WHAT IS INTEGUMENT? Integument/Integument system:

Debated as to whether or not your skin is an organ or organ system

Accounts for 16% of body weight 2 Major Components:

1-Skin or Cutaneous Membrane Epidermis Dermis Hypodermis

2-Accessory Structures Nails Exocrine glands

FUNCTIONS OF INTEGUMENTARY SYSTEM Protection Excretion (salts, water, organic wastes) Maintenance of body temp Synthesis of vitamin D3 Storage of nutrients (adipocytes) Detection of touch, pressure, pain, etc.

CUTANEOUS MEMBRANE Skin

Epidermis (superficial)DermisHypodermis (deep)

EPIDERMIS Thin skin=made of 4 layers of

stratified Squamous tissueMost of body

Thick skin=made of 5 layers Hands and feet

LAYERS OF EPIDERMISMade of Stratified Squamous epithelium

Stratum Corneum (superficial) Stratum Lucidum Stratum Granulosum Stratum Spinosum Stratum Basale or Germinativum

(deep)Cells eventually pass through all layers

or can eventually be found

STRATUM CORNEUM

Surface skin (most superficial) Highly keratinized: thick, interwoven 15-30 days to get from stratum basale to

stratum corneum Stay at stratum corneum for 2 weeks b/f shed Loose 500 mL (1 pint) water a day through

skin

Blisters: water retention between dermis/epidermis under high stress

STRATUM LUCIDUM Found in thick skin

Glassy, tough Filled with keratin

Fibrous proteins—make up your hair and nailsLayer missing in “thin” areas

STRATUM GRANULOSUM “Grainy Layer”

3-5 layersHave stopped dividing at this timeHigh in keratin

Makes cells flatter and thinner

STRATUM SPINOSUM “Spiny Layer” 8-10 layers Langerhans Cells

=participate in immune response

STRATUM BASALE Innermost Closest to basement membrane Sends projections into dermis (below

basement membrane)Called epidermal ridgesGive skin the whorls of fingertips

Basal cells =stem cells to make more skin Merkel Cells =sense touch where no hair is

present Melanocytes =skin tone

SKIN COLOR Due to interaction of Epidermal

Pigmentation and Dermal Circulation

EPIDERMAL PIGMENTATION 2 Pigments that control your skin

color1-Carotene (orange-yellow)

Found in stratum corneum2-Melanin (brown, yellow-brown,

black)Found in stratum basaleprotects us from UV radiationMelanocytes produce

Dark skin = increased amount of Melanin production not increased amount of individual Melanocytes

DERMAL CIRCULATION Gives pale or flushed look Better circulation =flushed Reduced circulation=pale

STOP

WHY UV-RADIATION IS BAD!

Damages DNA of the cell, causing mutations and promoting cancer development

Read bottom of 147(Melanocytes-Dermal Circulation)

WHY UV-RADIATION IS GOOD! VITAMIN D3

When exposed to sun, epidermal cells make D3, then the liver converts D3, and the kidney makes calcitriol. Calcitriol=ability to absorb calcium and

phosphorous(no calcitriol=impaired bone maintenance and

growth)

EPIDERMAL CONDITIONS Freckles

Areas where melanocytes are producing a higher than normal rate of melanin.

BirthmarksNon-vascular

Overgrowth of melanocytes Tattoo’s

THE DERMIS1. Papillary Layer

Areolar tissue, capillaries, sensory neurons

Supplies epidermis2. Reticular Layer

Collagen and elastic fiber

WRINKLES AND STRETCH MARKS

Collagen fibers=strong, resists stretching BUT bend easily

Elastic fibers=stretch and return=flexible, elastic dermisAging, hormones, and excess UV = weakened

fibers WrinklesExcessive stretching past fibers capabilities lead

to damaged fibers=stretch marks Caused by: pregnancy, major weight loss/gain

SOLUTION: Retin-A from vitamin A increases blood flow to dermis which increases chances for repair

ACCESSORY STRUCTURES-HAIR

5 million hairs 98% not on head

Hair Follicle=organ when hair is grown

Hair Root=anchors hair to skin

Hair Shaft=part you see

ACCESSORY STRUCTURES-HAIR

Is hair living?No-Comprised of non-living

cells Hair follicles are

How is color determined?Pigment produced by

melanocytes The biochemistry of these

structures is affected by DNAHormonal/Environmental

affects

FUNCTIONS OF HAIR Protection (eye lashes, head,

sensory, ears, nose) Root hair plexus=sensory

nerve around each hair follicle

Arrector Pilli-smooth muscle attached to hair follicle=when stimulated, contracts, causes “goose bumps”Stimulated by emotional

states, response to cold

GROWTH AND REPLACEMENT OF HAIR Hair growth cycle=2-5 years .33mm/day Hair loss occurs when the follicle

becomes inactive and shrinks Over time, the connection breaks=hair

loss The old hole sheds, new one forms

HAIR: REAL LIFE APPLICATION Male Pattern Baldness

Decrease in hormones circulating in the blood

Alopecia1 in every 100,000Complete hair loss all over bodyGeneticCauses death of hair follicles

ACCESSORY STRUCTURE-GLANDS IN THE SKIN Sebaceous (Oil Glands-Holocrine)

Share a duct with hair Waxy, oil secretions

Apocrine Sweat Glands (armpits, around the nipples, groin) Odorous, sticky Through hair follicle Begin at puberty

Merocrine Sweat Glands (all other sweat) 2-5 million High numbers in palms/soles

ACCESSORY STRUCTURE-NAILS Provides protection to finger Nail Body cover nail bed Production at nail root Lunala is pale=lack of blood

vessels Is dead, tightly compressed

keratin packed cells

THE HYPODERMIS OR SUBCUTANEOUS Not part of integument but

important for stabilizationAreolar/Adipose tissueElasticArea for injections