Functions of Body Membranes

-Line or cover body surfaces

-Protect body surfaces

-Lubricate body surfaces

Cutaneous Membrane (skin)

-dry membrane

-outermost protective boundary

-superficial epidermis

*keratinized stratified squamous epithelium

-underlying dermis

*mostly dense connective tissue

Mucous Membrane

-composed of epithelium resting on a loose connective tissue membrane (lamina propria)

*type depends on site

-lines body cavities that open to the exterior body surface-moist

-often adapted for absorption or secretion

Serous Membranes

-a layer of simple squamous epithelium resting on a thin layer of areolar connective tissue

-lines open body cavities that are closed to the exterior of the body

-serous layers are separated by serous fluid

Specific Serous Membranes

-Peritoneum

*abdominal cavity

-Pleura

*surrounds thelungs

-Pericardium

*around the heart

Synovial Membrane

-soft areolar connective tissue-no epithelial cells

-lines fibrous capsules surrounding joints

-provide a smooth surface and secrete a lubricating fluid

-Bursae-small sacs of connective tissue along with tendon sheaths provide cushion-knee

Integumentary System (skin)

-skin-cutaneous membrane

-integument-covering

-skin derivatives

*sweat glands

*oil

*hair

*nails

Skin Functions-(from table 4.1)

-mechanical damage-bumps and cuts

-chemical damage-acid and base

-bacterial damage-infection

-ultraviolet radiation-sunlight

-thermal damage-heat and cold

-desiccation-drying out

-Aids in heat regulation

-Aids in excretion of urea and uric acid-sweating

-synthesizes vitamin D-molecules of cholesterol modify from sunlight

Epidermis-outer layer

-made up of stratified squamous epithelium-avascular

-often keratinized (hardened by keratin)-hard and tough

-keratinocytes-produce keratin (fibrous protein that makes the epidermis a touch protective layer)

Dermis-underlying layer

-made up of dense connective tissue

-blister-epidermis and dermis separate-fluid fills space

Hypodermis-deep to the dermis

-not part of the skin

-anchors skin to underlying organs

-composed mostly of adipos tissue (fat)

Layers of the Epidermis

-epidermis composed of up to five zones called strata

-from inside out- stratum basale, spinosum,granulosum, lucidum and corneum

Stratum Basale

-deepest cell layer-lies next to the dermis

-contains epidermal cells that receive the most adequate nourishment

-continuously undergoing mitosis

-daughter cells pushed upward away from nourishment to become part of epidermal layers closer to the skin surface

Stratum Spinosum

-becoming flatter and dying

Stratum Granulosum

-becoming flatter and dying

Stratum Lucidum

-only occurs in thick skin, where skin is hairless- palms and soles containing keratin and glycoprotein (water-repellent)

Stratum Corneum-outermost layer

-20-30 cell layers thick (about 3/4 of the epidermal thickness)

-shingle-like dead cells-completely filled with keratin (cornified cells)

-flakes off slowly and is replaced every 25-45 days

Melanin

-a pigment (ranges from yellow to black) produced by melanocytes

-melanocytes found chiefly in the stratum basale

-amount of melanin produced depends upon genetics and exposure to sunlight-exposure causes melanocytes to produce melanin-tanning

-freckles and moles-concentrated melanin in one spot

Dermis-your hide-holds body together

-two layers

*papillary layer

*reticular layer

Papillary Layer-upper dermal layer

-fingerlike projections called dermal papillae

*many furnish nutrients and others house pain receptors and touch receptors

**meissne's corpuscles

-capillary loops-provide nutrients to epidermis

-fingerprints-genetically determined; looped or whorled

Reticular Layer-deepest layer

-contains blood vessels, sweat and oil glands and deep pressure receptors

-nerve receptors-rich in nerves

-deep pressure receptors-pacinian corpuscles

-phagocytes found-protect/kill bacteria

Dermis-found throughout

-collagen

*toughness and hydration

-elastic fibers

*keeps skin young looking

*aging-fiber decrease, losing elasticity and begins to sag and wrinkle

Maintaining Momeostasis-temperature

-blood vessels-temperature is high, capillaries swell with heated blood, skin is redened & warm

-body radiates heat to surface

-temperature is low-reverse effect

Normal Skin Color Determinants-3 pigments

-Melanin-amount and kind

*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

-Emotional Stimuli

*redness or erythema-blushing, fever, hypertension

*pallor or blanching-stress, pale

*jaundice-yellowing-signifies liver disorder, excess bile pigments

Appendages of the Skin

-includes glands, hair, hair follicles, nails

*glands all exocrine-release secretions through ducts

Sabaceous Glands

-produce oil-sebum:everywhere but soles and palms

*sebum-lubricant for the skin

*sebum-contains chemicals that kill bacteria

-ducts usually empty into hair follicles-some empty on the skin surface

-glands are activated at puberty

Sweat Glands-aka suderiferous glands

-widely distributed in the skin-2.5 million per person

-two types: eccrine and apocrine

Eccrine-more numorous and found all over the body

-produce sweat: water salts, vitamin C, metabolic wastes

*acidic (4-6 pH)

-open via duct to pore on skin surface

-heat regulators

Apocrine-larger than eccrine

-ducts empty into hair follicles

Sweat

Composition

-mostly water

-some metabolic wastes

-fatty acids and proteins (apocrine only)

Function

-helps dissipate excess heat

-excretes waste products

-acidic nature inhibits bacteria growth

-odor is from associated bacteria-axillary (pits)

Hair

-safegaurd,sheild,protect from invasion

-produced by hair bulb

-consists of hard keratinized epithelial cells

-melanocytes provide pigment for hair color

Hair Follicle

-dermal and epidermal sheath surround hair root

Arrector Pili

-goosebumps

-smooth muscle

Nails

-scale like modification of the epidermis

*heavily keratinized

-stratum basale extends beneath the nail as the nail bed

*responsible for nail growth

-lack of pigment makes them colorless

Nail Structure

-free edge

-body

-root of nail

-epoychium

*proximial nail fold that projects onto the nail

Skin Homeostatic Imbalances

Infection

-athletes foot-aka tinea pedis

*caused by fungal infection

Boils and Carbuncles

-inflammation of hair follicles and sebaceous glands

*caused by bacterial infection

Cold Sores

-caused by virus-stress,fever,UV light

Infection and Allergies

-contact dermatitus

-exposures cause allergic reaction-poison ivy

Skin Homeostatic Imbalances (cont'd)

Impetigo

-Impet:attack-pink water filled lesions

*caused by bacterial infection-highly contagious

**chicken pox-virus causing

Psoriasis

-overproduction of skin cells-become dry, scaley

*cause is unknown

*triggered by trauma, infection, stress

Burns

-tissue damage & cell death caused by heat, electricity, UV radiation or chemicals

-Associated dangers

*dehydration

*electrolyte imbalance

*circulatory shock- inadequate circulation of blood

Rule of Nines

-way to determine the extent of burns

-body is divided into 11 areas for quick estimation- front and back

*each area represents about 9%

First Degree Burns

-only epidermis is damaged

-skin is red and swollen-sunburn

Second Degree Burns

-epidermis and upper dermis are damaged

-skin is red with blisters-no scarring if cared for properly

Third Degree Burns

-destroys entire skin layer-not painful:no regeneration

-burn is gray-white or black-skin grafting necessary

Critical Burns

-Burns are considered critical if:

*Over 25% of body has second degree burns

*Over 10% of body has third degree burns

*There are third degree burns on the face, hands,or feet

Skin Cancer

-cancer-abnormal cell mass

-Two Types

--Benign

*Doesn not spread (encapsulated)

--Malignant

*Metastasized (moves) to other parts of the body

-skin cancer is the most common type of cancer

Types of Skin Cancers

-Basal Cell Carcinoma

-Squamous Cell Carcinoma

-Malignant melanoma

Basal Cell Carcinoma

-least malignant

-most common type

-arises from stratum basale

Squamous Cell Carcinoma

-common on ears, back of hands, lip, scalp- sun induced

-arises from stratum spinosum

-metastasizes to lymph nodes-if not removed

-early removal allows a good chance of cure

Malignat Melanoma

-pigmented moles

-most deadly of skin cancers-incresing rapidly

-cancer of melanocytes

-metastasizes rapidly to lymph and blood vessels

*survival rate: 50%

-Detection uses ABCD rule

ABCD Rule

-A-Asymmetry

*Two sides of pigmented mole do not match

-B-Border Irregularity

*Borders of mole are not smooth

-C-Color

*different colors in pigmented area

-D-Diameter

*Spot is larger than 6 mm in diameter

Developmental Aspects of Skin

-Lanugo:downy type hair in soon to be born infant 5-6 months of development

-Vernix caseosa-white,cheesy substance

*protects baby's skin while in mother

-Adolescence:acne,puberty

-Old age: subcutaneous tissue decreases

*cold feeling, drying, thinning

*elasticity decreases; saging, wrinkles

*speeded: smoking, UV light

Hair

-loses luster-thinning

-alopecia:balding

*hair follicles degenerate

-graying:follicles degenerate, hari becomes colorless

*delayed reaction gene:activated

*amount of melanin production decreases