Integumentary System- Emerson Brown; Per. 4

Function of the Integumentary System

Body Membranes

Layers (5) of Epidermis

Skin Cancers: most common type of cancer; most important risk factor is UV radiation

Layers of Dermis: strong, connective tissue

Accessory Organs

Infections

Burns: tissue damage enflicted by heat, electricity, radiation, etc. (can lead to renal failure or circulatory shock)

Basal Cell Carcinoma

Squamous cell carcinoma

Melanoma

least malignant and most common

accounts for 80% of cancers

cells proliferate and invade dermis

Second most common type of skin cancer

arises from Keratinocytes

appears as a reddened papule on head, scalp, ears, lip, hands

cancer of melanocytes; most dangerous

1/3 develops from pre-existing moles

key to survival is detection

First Degree

Second Degree

Third Degree

full-thickness burn

nerves are destroyed

critical if 10% of body is third degree burns

only epidermis is damaged

redness, swelling, pain

takes two to three days to heal

damages epidermis and upper region of dermis

causes blistering; partial thickness burn

three to four weeks to heal

rule of nines: a method of computing the extent of burns

Treatment

requires the replenishment of calories through nutrients

preventing infection

removal of burned skin with the replacement of healthy tissue

Protection

Chemical Barriers

Physical Barriers

Biological Barriers

Cutaneous Sensation

Metabolic Functions

Blood Reservior

Excretion

skin is vulnerable to microorganisms, abrasions, temp. extremes, harmful chemicals; UV radiation

three types of barriers

skin secretes melanin

melanin provides a protective shield

skin cells secrete defensins

barrier capacity arises from stratum corneum

glycolipids

mortar

composed of dentric cells of epidermis and macrophages

dentric cells: apart of immune system by engulfing foreign invaders

dispose of viruses and bacteria

cutaneous sensory receptors: apart of nervous system

exteroceptors: a sensory receptor which receives external stimuli

stimuli arising outside the body:

lamellar: corpuscles alert us to bumps or contacts

Hair follicle receptors: report wind blowing

tactile: allows us to feel objects (clothing against skin)

Free nerve endings: senses painful stimuli (chemicals, heat, cold)

when sun bombards skin, cholesterol molecules are converted to vitamin D precursor; calcium cannot be absorbed without vitamin D

"disarms" many cancer causing chemicals

activates steroid hormones

vascular supply can hold about 5% of body's blood volume

nervous system constricts dermal blood vessels

body eliminates nitrogen-containing wastes (ammonia, urea, + uric sweat)

wastes are excreted through urine

profuse sweating is an important avenue water and salt loss

Cells: fibroblast, macrophages, mast, white blood cells,

Function: binds body together; two layers

Papillary

Reticular

aerolar connective tissue; collagen and elastic fibers

allows phagocytes to wander freely as they patrol for bacteria

dermal papille: indent overlaying epidermis; contains capillary loops

friction ridges: enhances ability to grip

80% of thickness of dermis

dense irregular connective tissue

dermal vascular plexus: network of blood vessels

cleavage (tension) lines: formed by separations; run longitudinally in skin of limbs and circular around neck and trunk

flexure lines: dermal folds (occur near joints; dermis is tightly secured to deeper structures

dermis folds and deep skin creases (visible on wrists, fingers, soles, and toes

stratum basale: attached to dermis, single row of cells; rapid division

stratum spinosum (prickly): several layers; does not exist in living cells

stratum granulosum: consists of one to five cell layers; process of keratinization occurs

stratum lucidum: smooth, seemingly translucent layer of the epidermis; dead flattened

stratum corneum: the horny, outer layer of skin

502_Layers_of_epidermis

epidermis: four cell types and five distinct layers

keratinocytes: produce keartin; tied together by derosomes; fpund in stratum basale; dead by the time they reach the skin surface

callus: thickening of dermis

melanocytes: spider-shaped epithelial cells; produces melanin and found in deepest layer.

Dendritic cells: arise from bone marrow and migrate to epidermis; ingest foreign substances; extends among surrounding keratinocytes

Tactile Epithelial: present at epidermal-dermal junction; associated with a dislike nerve ending

Hair

Nails: forms a clear protective coating on the dorsal surface; "tools" to pick up objects

Glands

Vellus hair: children and adult female hair; pale and fine

Terminal hair: coarse, long hair; eyebrows, scalp, etc.

appears in axillary region, chest and face of men

hair grows of 2mm per week

male pattern baldness: most common type of baldness

follicles respond to androgens with shorter growth cycles

nail matrix: responsible for nail growth; thickened proximal portion of nail body

lunule: "little moon"; white crescent matrix part of nail

nail folds: proximal nail fold projects onto the nail body

hyponychium: area below the nail

sweat glands (sudoriferous): distributed all over body (except nipples and genetaila); up to 3 million per person; two types

Eccrine Sweat glands

Apocrine glands

palms, feet, forehead

tubular glands

produces sweat and filtrates blood (sweat is 99% water and 1% salt

prevents body from overheating

heat sweating begins in forehead; emotional sweat begins on palms, soles, and axillary region

lies deep within dermis; ducts empty into hair

begins at puberty, may be the human's version of animal sexual scent glands

two types: ceruminous and mammary

Sebaceous glands: oil glands, alveolar glands

secrete sebum

cells accumulate oily lipids until they become too engorged and burst

develop as outgrowths of hair follicles

sebum softens and lubricates hair and skin

cutaneous

mucous "mucosae"

serous (serosae)

two layers: parietal and visceral: in between the two lies cavities and serous fluid

thin membranes which cover walls

pleurae: line the thoracic wall and cover the lungs

pericardium: encloses the heart

peritoneum: encloses the abdominopelvic viscera

organ system composed of keratinized stratified squamous epithelium (epidermis) firmly attached to a thick layer of connective tissue (dermis)

dry membrane

exposed to air and elements (unlike other body membranes)

line all body cavities that open to the outside of the body

digestive, respiratory, and urogenital tracts

moist membranes bathed by secretion

lamina propia: epithelial sheet lies directly over a layer of areolar connective tissue

adapted for absorption and secretion

many secrete mucous (ex. digestive and respiratory tracts secrete mucus, but that of the urinary tract doesn't

infection is common after skin is burned and it is important for doctors to prevent it

widespread bacterial infection is the leading cause of death in burn victims

skin graft helps prevent mass infection