2 groups of body membranes
1.) epithelial membrane - cutaneous, mucous, & serous membranes.
2.) connective tissue membrane - synovial membrane
• aka. covering & lining membrane.
• contain epithelial sheet always combined with underlying layer of connective tissue.
• superficial epidermis - keratinizing stratified squamous epithelium
• underlying dermis - dense fibrous connective tissue layer
• exposed to air (dry membrane)
• composed of epithelium resting on lamina propria
• lines all body cavities open to exterior
• "wet," moist membrane that is continuously bathed in secretions.
• adapted to secretions or absorption.
• composed of simple squamous epithelium resting on thin layer of areolar connective tissue.
• occurs in pairs
• has serous fluid
• thin, clear fluid that separate serous layers.
• allows organs to slide easily across the cavity wall & one another without friction as they carry routine functions.
• soft areolar connective tissue & contain no epithelial cells.
• line fibrous capsules surrounding joints.
- provides smooth surface & secrete a lubricating fluid.
• line bursae
• small sacs of connective tissue & tendon sheaths.
• cushions organs moving against each other during muscle activity.
• "covering the skin"
• keeps water & other molecules in the body.
• insulates & cushions the deeper body organs.
• protects entire body.
• regulates heat loss from body surface.
• acts as mini-excretory system
• manufactures proteins important for immunity & synthesizes Vitamin D.
Integument protection of the body
• Mechanical damage - bumps & cuts.
• Chemical damage - acids & bases.
• Thermal damage - hot & cold
• Ultraviolet radiation - sunlight
cutaneous sensory receptors
include touch, pressure, temperature, & pain receptors about external environment.
• made up of stratified squamous epithelium.
• capable of keratinizing, or becoming hard & tough.
subcutaneous tissue (hypodermis)
• deep to dermis
• adipose tissue
• not part of skin, but anchors the skin underlying organs.
• serves as shock absorber.
• insulates deeper tissues from extreme temperature changes occurring outside the body.
5 layers of epidermis (from inside out)
1.) stratum basale
2.) stratum spinosum
3.) stratum granulosum
4.) stratum lucidum
5.) stratum corneum
• deepest cell layer of epidermis.
• lies closest to the dermis.
• contains epidermal cells that receive adequate nourishment via diffusion of nutrients from dermis.
• aka. stratum germinativum.
• always undergoing cell division.
• move away from source of nutrition towards the surface of the epidermal layers.
- move through stratum spinosum --> stratum granulosum --> finally die, forming stratum lucidum.
• not present in all skin regions.
• occurs only where skin is hairless & extra thick.
- palms of hands & soles of feet.
• unable to get O2 & nutrients.
stratum lucidum unable to get O2 & nutrients
• full of keratin
• secretes H20-repelent glycolipid in extracellular space.
• distant from blind supply.
• outermost layer
• 20-30 cell layers thick (3/4 epidermal thickness)
• durable "overcoat" for body.
• sheds dandruff
stratum corneum "overcoat"
protects deeper cells from hostile external environment, water loss & helps resist biological, chemical, & physical assaults.
• spider-shaped cells
• found in stratum basale.
• stimulated by sunlight to produce melanin pigment (tanning).
• produce keratin
• contains melanin that shields DNA from damaging effects of U.V. radiation in sunlight.
• fibrous protein that makes epidermis a tough protective layer
• uppermost layer of the skin.
• helps prevent water loss from body surface.
• strong, stretchy envelope that helps hold body together.
• dense (fibrous) connective tissue.
• 2 major regions
• uneven & has peg-like projections from its superior surface.
• indent the epidermis above.
• contain capillary loops - furnish nutrients to the epidermis.
• deepest skin layer
• contains blood vessels, sweat & oil glands, & Pacinian corpuscles.
• have phagocytes
• responsible for toughness of the dermis.
• attract & bind water & help keep skin hydrated.
increased body temperature
• capillaries of dermis becomes engorged, or swollen, with heated blood.
- skin becomes reddened or warm.
decreased body temperature
• body conserves heat.
• blood bypasses dermis capillaries, keeping body temperature high.
decubitus ulcers (skin ulcer)
• occurs in bedridden patients who are not turned regularly or who are dragged or pulled across the bed repeatedly.
• pressure on body restricts blood supply & skin becomes pale or blanched.
• permanent damage eventually results in degeneration & ulceration of skin.
3 pigments of skin color
1.) amount & kind (yellow, reddish brown, or black) of melanin in the epidermis.
2.) amount of carotene deposited in the stratum corneum & subcutaneous tissue.
3.) amount of oxygen-rich hemoglobin in dermal blood vessels.
• skin appearing blue because hemoglobin is poorly oxygenated.
• common during heart failure & severe breathing disorders.
• black people's skin masks the effects of melanin but is apparent in mucous membranes & nail beds.
skin color influenced by emotion
• redness, or erythema
• pallor, or blanching
• Jaundice, or yellow cast.
• Brusies, or black-&-blue marks.
indicates embarrassment (blushing), fever, hypertension, inflammation, or allergy.
• people become pale under certain types of emotional stress.
• can signify anemia, low blood pressure, or impaired blood flow to area.
Jaundice (yellow cast)
• yellow skin tone usually signifying liver disorder in which excess bile pigments are absorbed into blood, circulated throughout the body, & deposited in body tissues.
Bruises (black-or-blue marks)
• sites where blood has escaped from circulation & has clotted in the tissue spaces.
• hematomas - masses of blood clots.
• cutaneous glands, hair & hair follicles, & nails.
• arises from epidermis & play unique role in maintaining body homeostasis.
sebaceous (oil) glands
• found all over skin except on palms of hands & soles of feet.
• ducts empty into a hair follicle.
• produces sebum.
• mixture of oily substances & fragmented cells.
• lubricant that keeps skin soft & moist.
• prevents hair from becoming brittle.
• contains chemicals that kill bacteria & prevent bacteria on skin surface from invading skin regions.
• aka "cradle cap"
• found on infants.
• overactivity of sebaceous glands
• begins on scalp as pink, raised lesions that gradually from a yellow to brown crust that sloughs off oily scales.
• more numerous & found all over the body.
• supplied with never endings that cause then to secrete sweat when external temperature or body temperature is high.
• clear secretion that is primarily water + salts (sodium chloride), vitamin C, metabolic wastes (ammonia, urea, uric acid), & lactic acid.
• acidic (pH 4-6) - inhibits growth of bacteria.
• body can lose up to 7 liters of water.
• confined to axillary & gential areas.
• larger than eccrine glands.
• secretion contains fatty acids + proteins + eccrine secretions.
• begin to function during puberty under influence of androgens (male sex hormones).
apocrine gland secretion
• milky or yellowish color.
• secretion is odorless but when bacteria that live on skin use its proteins & fats as nutrient source for growth, takes on musky unpleasant odor.
minor protective functions of hair
• guard head against bumps.
• shield eyes (eyelashes)
• keep foreign particles out of respiratory tract (nose hairs)
growth zone in hair bulb from stratum basale epithelial cells, growing further away from region until keratinized and die.
• surrounds the cortex.
• single layer of cells that overlap one another like shingles on a roof.
- keeps hair apart & from matting.
• most heavily keratinized region.
• cuticle is most subject to abrasions - tends to wear away at tip of shaft, allowing keratin fibers in the inner hair regions to frizz out.
• aka. "raiser of hair"
• connect each side of the hair follicle to the dermal tissue.
• arrector pili pulls hair upright, dimpling the skin surface.
• more useful on animals than on humans.
scale-like modification of the epidermis that corresponds to the hoof or claw of other animals.
• aka. tinea pedis.
• itchy, red, peeling condition of the skin between the toes, resulting from fungus infection.
cold sores (fever blisters)
• small fluid-filled blisters that itch and sting.
• caused by herpes simplex infection.
• virus localizes in a cutaneous nerve - remains dormant until activated by emotional upset, fever, or UV radiation.
• usually occur around the lips and in oral mucosa of mouth.
• itching, redness, and swelling of the skin, progressing to blistering.
• caused by exposure of skin to chemicals (poison ivy) that provoke allergic responses in sensitive individuals.
• pink, water-filled, raised lesions that develop a yellow crust and eventually rupture.
• commonly around the mouth and nose.
• caused by highly contagious staphyloccus infection
• common in elementary school-aged children.
• chronic condition, characterized by overproduction of skin cells that results in reddened epidermal lesions covered with dry, silvery scales that itch, burn, crack, and sometimes bleed.
• tissue damage and cell death caused by intense heat, electricity, UV radiation (sunburn), or certain chemicals (acids).
• body loses fluids of containing proteins & electrolytes.
- can lead to kidney failure and circulatory shock.
rule of nines
• determines how much of the body surface is burned.
• divides body into 11 areas --> 9% each area + 1% (around genitals).
• only epidermis is damaged.
• area becomes red and swollen.
• not usually serious & generally heal in 2-3 days without any special attention
• Ex: sunburn.
• injury to the epidermis and upper region of the dermis.
• skin is red and painful, & blisters appear.
• regrowth (regeneration) of epithelium can occur
• no scaring if taken care of to prevent infection.
• aka full-thickness burns
• destroy entire thickness of skin
• burned area appears blanched (gray-white) or blackened.
• never endings are destroyed so burn area is not painful.
• regeneration is not possible.
conditions of critical burns
1.) Over 25% of body has second-degree burns.
2.) Over 10% of the body has third-degree burns, or
3.) There are third-degree burns of the face, hands, or feet.
Basal Cell Carcinoma
• least malignant and most common skin cancer.
• stratum basale altered so keratin is not formed.
• cancer lesions occur most often on sun-exposed area of the face - appear as shiny, dome-shaped nodules that later develop a ulcer with "pearly" beaded edge.
• slow-growing, metastasis occurs before noticed.
• full cure - 99% of lesions removed surgically
Squamous Cell Carcinoma
• arises from stratum spinosum.
• lesions appear scaly, reddened papule - form shallow ulcer with firm, raised border.
• appears most often on scalp, ears, dorsum of hands, & lower lip.
• grows rapidly & metastasizes to adjacent lymph nodes if not removed.
• believed to be sun-induced.
• cure - removed surgically by radiation therapy.
• cancer of melanocytes
• arises from accumulated DNA damage in skin cell
• appears as spreading brown to black patch.
• metastasizes rapidly surround lymph & blood vessels.
• 50% survival rate.
• for recognizing melanoma
• (A) Asymmetry
• (B) Border irregularity
• (C) Color.
• (D) Diameter
Color (ABCD rule)
Pigmented spot contains areas of different colors (blacks, browns, tans, & sometimes blues and reds).
• downy type of hair covered on soon-to-be-born infants.
• hairy cloak usually shed by birth.
• white, cheesy-looking substance covering skin of newborn.
• produced by sebaceous glands
• protects baby's skin while floating in water-filled sac inside mother.
• small white spots on baby's nose & forehead due to accumulations in the sebaceous glands.
• normally disappear by the third week after birth.