chapter 5. integument/integument system: debated as to whether or not your skin is an organ or...
TRANSCRIPT
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