Integumentary System (CH 6) Cutaneous Membrane (skin)

contains the following tissues

Stratified squamous epithelium Glandular epithelium Dense irregular connective Adipose connective Smooth muscle Nervous

7 FUNCTIONS 1. Protection

from water loss, injury, chemicals, and microorganisms pH level of 5­6 to prevent microorganism growth

Langerhans cells (epidermis) Type of white blood cell; assimilates, processes, and carries antigens(a

toxin/foreign substance) to nearest lymph node for further immune system processing

Macrophages and mast cells (dermis) Immune system

2. Excretion urea + uric acid through sweat

3. Regulation of body temp. (negative feedback mechanism) stimulus → receptors(receive) → control center → effectors (exit) → response

Hyperthermia → abnormally high Hypothermia → abnormally low

4. Sensory reception Light touch = Meissner's corpuscles

dermal papillae concentrated in fingertips, palms, soles, eyelids, tip of the tongue

and genitals Pressure detection = Pacinian corpuscles

dermis and subcutaneous region 5. Contains immune system cells

Keratinocytes → stimulates white blood cell production Langerhans cells + macrophages Interacts with T­helper cells (suppress/stimulation of immune system)

6. Synthesizes vitamin D

needed for bone/tooth development 7. Acts as a blood reservoir

dermis houses 10% of body’s blood vessels skin requires 1­2% of body’s blood

AGED SKIN Skin becomes scaly Age spots appear Epidermis thins Dermis reduces Loss of fat Wrinkling Sagging Sebaceous glands secrete less oil Melanin production slows Hair thins Number of hair follicles decrease Nail growth becomes impaired Sensory receptors decline Body temp. unable to be controlled Diminished ability to activate Vitamin D

2 LAYERS OF SKIN

1. Epidermis Keratinized (dead/fibrously structured cells) stratified squamous epithelium Avascular Melanocytes (produce melanin = skin color) Thickest on palm + soles (most friction ­ 0.8­1.4 mm)

Layers of the Epidermis Characteristics

Stratum Corneum Many layers of keratinized epithelial cells (flattened

with no nucleus b/c dead)

Stratum Lucidum Cells appear clear; nuclei, organelles and cell membrane are no longer visible

Stratum Granulosum 3­5 layers of flattened granular cells; contain shrunken fibers of keratin and shriveled nuclei

Stratum Spinosum Many layers of cells w/ centrally located large, oval nuclei + developing fibers of keratin; cells become flattened

Stratum Basale single row of cuboidal/ columnar cells (dividing and growing) + melanocytes

2. Dermis

1­2mm thick on average FUNCTIONS → bind epidermis + underlying tissue & nourish the epidermis muscle cells, sensory receptors, blood vessels, hair follicles, and glands

Layers of Dermis Characteristics

Papillary 20% loose connective tissue + papillae (finger­like projections EX: forms fingerprints) + Meissner corpuscles

Reticular 80% dense connective tissue + bundles of collagen, elastic, and reticular fibers (gives skin strength + resilience) + Pacinian corpuscles

Accessory Structures

Hair follicles epidermal cells tube­like depression extends into dermis hair root + shaft + papilla dead epidermal cells melanin arrector pili muscle

Nails

nail plate + bed + lunula

Sebaceous glands (oil)

usually associated with hair follicles holocrine glands + sebum secretion NONE on palms and soles

Sudoriferous Glands (sweat)

widespread on skin originates in deeper dermis or hypodermis eccrine + apocrine +ceruminous + mammary

SUBCUTANEOUS LAYER/ HYPODERMIS (Beneath the Skin)

loose connective + adipose insulates contains major blood vessels

SKIN COLOR

Genetic Factors varying amounts of melanin + granules (thicker/ bigger = darker) albinos have no melanin

Environmental Factors sunlight + UV light + X rays = darker melanin

Physiological Factors dilation of dermal blood vessels constriction of dermal blood vessels accumulation of carotene Jaundice (yellowing)

HEALING CUTS

CLINICAL APPLICATION

Epidermolysis Bullosa hereditary (two recessive genes from each parent make it) children born with inability to produce collagen­7 protein

lacking glue that binds inner and outer layer of skin together skin just tears apart (like velcro failure)

Acne Vulgaris MOST COMMON SKIN DISORDER sebum + epithelial cells clog glands anaerobic bacteria trigger inflammation

whiteheads + blackheads hormonally induced androgens stimulate sebum production treatment → antibiotics, topical creams, or birth control pills

Athlete’s Foot (moist environments + spread by contact) fungal infection

skin + toes + soles Ringworm (moist environments + spread by contact)

fungal infection ring pattern

Birthmark (Nevus) over 80% babies have one 2 TYPES

Vascular Pigmented

common types are café au lait spots, moles, port­wine stains, Mongolian spots, and hemangiomas

rare = tumor growth or disfigurement

Boil = bacterial infection of skin Carbuncles = bacterial infection spread into subcutaneous tissue Eczema

non­contagious blistering, crusting, bleeding, scaling, oozing, and itching some are hereditary

Psoriasis skin growth of abnormally high rate

red patches + silvery scales related to immune system can be hereditary

Cancer (skin) Carcinomas

MOST COMMON TYPE OF SKIN CANCER epithelial cells squamous/basal types treatment → surgical removal

Melanomas melanocytes harder to treat tanning bed increase = increase in last 20 yrs

Rule of Nine (burns)

1st degree (superficial partial­thickness burn) only epidermis

edema (swelling) +shedding area = red heal w/ no scar

2nd degree (deep partial­thickness burn) epidermis + dermis

fluid escapes from capillaries and collects in epidermal cells = blistering area = red/ waxy white usually heals w/o scarring

3rd degree (full­thickness burn) epidermis + dermis + accessory structures

area = leathery/red/black/white skin grafts often necessary (autograft or homograft) scarring will occur