Anatomy CH 5 Integument System

• 1. Protection - cushions and insulates the deeper organs & protects body from bumps, scrapes, cuts, chemicals, & invading microorganisms
• 2. Temperature regulation - the skin's rich capillary network & sweat glands regulate the loss of heat from the body, helping to control body temperature
• 3. Excretion - acts as a miniature excretory system when urea, salts, & water are lost through sweat
• 4. Production of Vitamin D (metabolic function) - epidermal cells use UV radiation to synthesize vitamin D
• 5. Sensory Reception (cutaneous sensory organ) - by sensing touch, pressure, temperature, & pain, these receptors keep us aware of conditions at the body surface
• 6. blood reservoir
• 7. water proofing - does not dissolve in water
• 8. insulation - maintain certain body temperature

• - a keratinized stratified squamous epithelium
• - the superficial region that is a thick epithelial tissue
• - avascular
• - depends on the diffusion of these materials from the underlying dermis
• - responds to pressure or injury to the skin

• - produce keratin, a tough fibrous protein that gives the epidermis its protective properties
• - also produce antibiotics & enzymes that detoxify the harmful chemicals to which our skin is exposed
• - arise at lower part of epidermis & are pushed up as new ones are created. as they reach the top they flatten out & then filled with keratin & have died.
• - we get a new epidermis every month

• - make melanin (dark pigment) which is transferred to keratinocytes
• - protects DNA from UV ray damage
• - production is increased as a result of UV exposure
• - made in membrane-walled granules & then transferred through the cell procfesses
• (spider-legs) to nearby keratinocytes

touch receptor associated with a sensory nerve ending

• star shape cells that form part of immune system & use receptor mediated endocytosis to engulf foreign substances
• - alarm

• thick skin - covers palms & soles & consist of 5 layers (or strata-bed sheets)
• thin skin - covers the rest of the body with only 4 strata present

• - deepest epidermal layer
• - consists of a single row of cells, mostly stem cells representing the youngest keratinocytes
• - mitosis occurs (high rate)
• - contains living cells
• - gives rise to newly formed keratinocytes & melanocytes

• - a spiny layer with several cell layers thick
• - cells of this layer contain thick bundles of intermediate filaments, which consist of a tension-resisting protein pre-keratin
• - contains living cells
• - also has langerhans cells
• - a layer of mature keratinocytes that have formed tonofilaments (prekeratin intermediate filaments)

• -a granular layer that is thin
• - consists of three to five layers of flattened keratinocytes that change to become waterproof and keratinized
• - contains living cells
• - has many tonofilaments, granules of keratohyalin (forms keratin), & lamellaeted granules (waterproofing glycolipids)
• - plasma membrane also thickens

• - a clear layer occuring in thick skin only (not thin skin)
• - consists of a few rows of flat, dead keratinocytes
• - too far from capillaries & since the cells do not get any nutrients, they die

• - a horny layer that is the most external part of the epidermis many cells thick (thicker in thick skin than in thin skin)
• - a layer of dead cells that can still perform so many functions
• - both the keratin and the thickened plasma membranes of cells in the stratum corneum protect the skin against abrasion & penetration
• - glycolipid between its cells keeps this layer waterproof
• - cells of this layer are shed regularly (dandruff from scalp & flakes from skin)
• - protects against abrasions & entrry of foreign substances

• - a fibrous connective tissue
• - has two layers: papillary & reticular layer
• - collagen fibers of dermis give skin its strength & resilience

• - makes up the top 20% of the dermis
• - is areolar connective tissue containing very thin collagen & elastic fibers
• - forms the dermal papillae (nipples) that are fingerlike projections that extend into the overlying epidermis
• -

• - makes up the second half of the dermis (80% of the thickness)
• - contains dense irregular connective tissue high in collegan
• - named for its networks of collagen fibers
• - reticular fibers give skin its elasticity and collagen makes it strong & resilient

• - fatty hypodermis with two other names..superfricial fascia and subcataneous layer
• - consists of both areolar & adipose connective tissue
• - stores fat
• - anchors skin to underlying structures
• - an insulator (helps prevent heat loss from the body) due to adipose tissue

• *Melanin - ranges from yellow to reddish to brown to black and variations in skin color in humans result from differences in both the amount & type of melanin produced. areas of concentrated melanin storage are known as mole, freckles, and birth marks
• *carotene - yellow-orange pigment that the body obtains from vegatable sources
• *hemoglobin - when oxygenated it is red & gives skin a pinkish to red tone seen in skin low in melanin. Also in bruising hemoglobin & red blood cell break down to create blue and yellow tones

• - corresponds to the hoof or claw of other mammals
• - enable us to pick up small objects & scratch the skin when it itches
• - made up of dead, keratinized cells
• - has a distal free edge, a body, and a root

• - where the nail rests on
• - contains only the deeper layers of the epidermis

• formed by the nail bed when the bed thickens at the root & the proximal end of the nail body
• - the actively growing region

• - lunule means "little moon"
• - is white crescent
• - located under the nail's proximal region

the lateral & proximal borders of the nail are overlapped by skin folds

• - another name for "cuticle"
• - proximal nail fold projects onto nail body

• - flexible strand made of dead cells filled with hard keratin
• - to sense things that lightly touch the skin
• - hair on the scalp protects head against direct sunlight in the summer & against heat loss on cold days
• - eyelashes shield the eyes
• - nose hairs filter large particles such as insects & lint from inhaled air

the part embedded in the skin

• - the part that projects above the skin surface
• - composed of three layers: cuticle, cortex, & medulla
• - shape of the shaft determines the type of hair

• - the root of the hair
• - extend from epidermal surface into the dermis
• - deep end of follicle is expanded, forming a hair bulb, a knot of sensory nerve endings wraps around each ahir bulb to form root hair plexus
• - associated with sebaceous gloands & arrector pili muscle

where the deep end of the follicle is expanded

a knot of sensory nerve endings wraps around each hair bulb

• - a bundle of smooth muscle cells
• - a raiser of the hair

• - greasy
• - skin's oil glands
• - occur over entire body except palms and soles
• - simple alveolar glands with several alveoli opening into a single duct
• - sebum (animal fat) collects dirt, softens & lubricates hair and skin, prevents hair from becoming brittle, and keeps the epidermis from cracking
• - these glands of sebaceous glands are influenced by sex hormones
• - has holocrine secretion: this excretory gland releases the sebum when the glandular cells become too full of product and burst

• - another name for sudoriferous glands
• - sweating prevents overheating of the body because sweat cools the skin as it evaporates
• - a filtrate of blood that passes through the secretory cells of the sweat glands & is released by exocytosis
• - sweat is 99% water & acidic (retards growth of bacteria on the skin)
• - contains 2 types of sweat glands:P eccrine & aprocine

• -secreting glands
• - produce true sweat
• - opens at a pore

• - produce a special kind of sweat consisting of fatty substances & proteins
• - causes body odor, respond to hormones, foreplay, & menstrual cycle changes

Aprocrine & Eccrine Glands

• - waxy
• - modified aprocrine glands in the lining of the external ear canal

modified to secrete milk

tissue damage inflicted by heat, electrcity, radiation, extreme friction, or certain harmful chemicals

• - only the epidermis is damaged
• - symptoms include redness, swelling, & pain
• - inflamattion results
• - heal in a few days without special attention
• - example: sunburn is usually a 1st degree burn

• - involve injury to the epidermis & upper part of the dermis
• - inflammation occurs, blisters appear
• - symptoms: blisters appearing as fluid accumulates, redness, swelling, pain
• - skin regenerates with little or no scarring in 3-4 weeks if care is taken to prevent infection

• - consume the entire thickness of the skin
• - appears white, red, or blackened
• - because of fluid loss and infection, should not wait for the skin to regenerate on its own. A skin graft is used on the burn area to treat it.

• least malignant and most common of skin cancer of the stratum basale, slow growing, & rarely undergoes metastasis.
• - appears as nodule with a central ulcer & a pearly edge

• arises from the keratinocytes of the stratum spinosum, grows rapidly, metastasizes
• - a chance of complete cure is 99% good
• - appears as reddened papule

• a deadly cancer of melanocytes and most dangerous kind of skin cancer
• - often arises from existing moles, metastasizes quickly, and is resistant to chemotherapy

• *infants: born coated with a layer of vernix caseosa (an oily waterproofing substance)
• *adolscence: onset of puberty activates sebacceous glands & increases acne. skin is at its best form in 20's and 30's, the skin damage becomes evident
• *middle age: skin becomes dry & itchy because lubricating glands are not as productive, oily skin ages better