Chapter 4

Skin and Body Membranes

BODY MEMBRANES

• _________________________cover surfaces,line body cavities and forms protective-sometimes lubricating –sheets around organs

I.Classification of Body Membranes

• A) EPITHELIAL MEMBRANES– Covering and lining membranes– All have an underlying sheet of connective

tissue

• 1) Cutaneous Membranes= skin• Superficial epidermis

is____________________________________• Underlying dermis is dense(fibrous) connective

tissue.The superficial tissue is exposed to air and is a ________________________________

Composed of keratinizing stratified squamous epithelial

Dry membrane

• 2) Mucous Membranes-made of varying types of epithelial tissue resting on a loose connective tissue called ____________________ and lines all membranes that open to the exterior(hallow organs of respiratory tract,digestive,urinary and reproductive…

• Mucosa refers to location,not cellular makeup….But most mucosa are stratified squamous (mouth and esophagus) epithelium or simple columnar (rest of digestive tract)----all wet and bathed in secretions)

Lamina propria

3)Serous membranes(serosa)-

• Has a layer of simple squamous epithelium on a thin layer of ________________________________

• Serosa are closed to the exterior (except for dorsal body cavities and joint cavities)

Areolar connective tissue

• Occur in pairs…The __________________lines a specific portion of the ventral body cavity

• Parietal layer folds in itself to form ________________-covers outside of the organs in that cavity

• Serous layers separated by___________________-secreted by both membranes

Parietal layerSerous fluid

Visceral layer

• Serous fluid allows organs to slide against ea. Other and cavity w/o friction

SEROUS NAMES RELATED TO LOCATION

– ______________________covers abdominal cavity

– ____________________-surrounds lungs– _______________________surrounds heart

peritoneum

pleural

pericardium

Connective Tissue membranes

• Composed of ______________________and has NO epithelial cells-line capsules surrounding joints

• Line small sacs of connective tissue called bursae and the tubelike tendon sheath----all cushioning organs against each other and tendon across bone

Soft areolar connective tissue

II.The Integumentary Sysyem(skin)-cutaneous membrane

• The Integumentary Sysyem(skin)-cutaneous membrane

• functions –most importantly protective….against mechanical damage,chemical damage,

• bacterial damage,• UV effects,thermal effects and

dessication(drying out)• ---also aids in controlling body heat• ---aids in excretion of urea and uric acid• ----synthesizes Vitamin D

• The uppermost layer is full of _____________-and is cornified or hardened-help prevent water loss

• Capillaries and sweat glands work on thermal control

• ____________sense touch,pressure,temperature and pain

keratinCutaneous sensory receptors

Structure of skin

– Epidermis-stratified squamous epithelial capable of keratinizing(hardening)

– _________-underneath-mostly dense connective tissue

– Epidermis and dermis strongly connected,but some abuse can cause them to separate—interstitial fluid comes between layers making a _____________

– _____________is below dermis and mostly adipose----not actually considered part of skin,but attaches skin to organs beneath---works as “shock absorber” and insulates from extreme temperatures

dermis blisterSubcutaneous tissue

1)Epidermis-• has 5 layers or _______________.From inside

out they are stratum basale,spinosum,granulosum,lucidum and corneum

• avascular• most cells are

______________________________which make keratin

strata

keratinocytes

• Stratum basale-closest to dermis and connected along a wavy borderline.Contains epidermal cells that that get the most nourishment by diffusion from dermis;constant cell division-MILLIONS OF NEW CELLS DAILY(also called stratum germanitivum),daughter cells pushed upward

• Stratum Spinosum and stratum granulosum become flatter and increasingly full of keratin

• When the previous cells die,they form the clear _________________________________-not in all skin regions-only where skin is hairless and extra thick-ie.palms and soles;it secretes a water repellent glycolipid into extracellular space;distant from blood supply,so little nutrients-doomed cells

Stratum lucidum

• OUTERMOST Stratum corneum—20-30 cells layers thick and is ¾ of epidermal thickness;cornified,shinglelike dad cells,filled w/ keratin;protects lower cells;dandruff sloughs off from here

• We have a totally new epidermis every 25-45 days• ___________________pigment that ranges in color

from yellow to brown to black produced by melanocytes(in stratum basale).When skin is exposed to sun,this stimulates these cells tomake more of the pigment---THUS tanning

melanin

• Melanin accumulates in membrane bound granules called __________________.They move to the end of the melanocytes and taken up by keratinocytes .THERE,melanin froms a pigment umbrella over superficial side of nuclei-shielding DNA from UV

• _______________and moles are where melanin are concentrated in one spot

melanosomesfreckles

2)dermis-‘hide

– strong,stretchy– dense fibrous connective tissue– ___________________upper dermal

region;______________-peglike projections from superior surface-many containing capillary loops-thus nutrients;some have pain receptors-___________________ or touch receptors-_________________________________

Papillary layer

Dermal papillae

Free-nerve endings

Meissner’s corpuscles

• Has whorled rings on soles and palms,increasing friction and gripping ability----genetically determined…..sweat pores provide for fingerprints

– 2)_______________________________deepest skin layer w/blood vessels,sweat and oil glands and _______________________________deep pressure receptors;phagocytes act here at reticular layer

– Collagen and elastic fibers found in dermis.collagen gives toughness and attract water for hydration.Elasisic fibers give elasticity that declines w/age

– Many blood vessels help w/ body temp.homeostasis.skin is red when hot due to engorging of blood

Reticular layer

Pacinian corpuscles

– ___________________________________ happen in bedridden patients not turned regularily-pressure restricts blood supply and redness when pressure is released

– Rich nerve supply

Decubitus ulcers

C-Skin Color-3 pigments:

• 1-melanin in epidermis• 2-carotene in stratum corneum and

subcutaneous tissue• 3-O2-rich hemoglobin in dermis

• ----varying amounts of thr above create the numerous skin colors.Which is showing up more in Caucasians?_________________________

• ________________________hemoglobin is poorly oxygenated---can happen during heart failure and severe bleeding

hemoglobin cyanosis

What else affects skin color?:

• Emotions and various disease states:– ___________________-redness-

blushing,hypertension,inflammation,allergy– ___________________-blanching-pale—fear,anger

also anemia,low blood pressure,impaired blood flow

– ___________________-yellowness-liver disorder– ____________-sites wher blood has escaped and

clotted in tissue spaces;can happen w/disese or vitamin C deficiency

• _________________-clotted blood mass

erythema pallor jaundice

bruiseshematomas

D.Appendages of the Skin

• 1-__________________________________-exocrine glands-release secretions to skin’s surface via ducts

• a)Sebaceous glands-oil glands-excepts on palms and soles—some open into hair follicle and some to surface

• ________________-is product-clump of oil and cells;keeps skin moist and prevents hair from drying out

Cutaneous glands

sebum

• ______________(sudoriferous glands)-many in the skin-2 types: 1)eccrine glands-all over body and make sweat(mostly water,NaCl,vitamin C and tarces of metabolic wastes(ammonia, urea,uric acid and lactic acid.It is acidic and inhibits bacteria….sweat comes through a poer(not same as facial pores);helps regulate temp.(37 C

Sweat glands

• 2)_____________________________-mostly at axillary and genital areas;ducts empty into hair follicles;contains fatty acids and proteins—giving milky/yellowish color.It is odorless,but that changes whe bacteria use it as food:function at onset of puberty regulated by androgens(male sex hormones)----have been connected to sexual foreplay

Apocrine glands

3-Hair and Hair Follicles

• . • 1)Hairs made by hair follicles and is flexible

epithelial structure;root in ________________and shaft protrudes It is formed by mitosis of stratum basale epithelial cells in matrix(growth zone)-become keratinized and die as pushed forward---mostly hair contains protein

• Hair has central core called a medulla surrounded by a cortex.This is covered by a cuticle(most keratinized region)-gives strength

• Hair pigments made by melanocytes in hair bulb

Hair follice

• Variety of shapes and sizes(eyebrows v. head then skin hair).If shaft is flat and ribbonlike-hair curly or kinky.If shaft is round-straight or coarse hair

• Hair all over except soles,palms,nipples and lips• Fastest growing tissue in body• Have hormonal control

• 2) hair follicles-contain inner epidermal sheath that forms hair/outer dermal sheath is connective tissue/papilla yield blood supply to matrix in hair bulb

• ______________________________smooth muscle that raise hair in response to temp

Errector pilli

• 3) Nails-scalelike product of dermis(corresponds to hoof or nail)

• Each nail has a _______________,a body(visible and a root(imbedded in skin)

• Nail bed in stratum basale and inner ____________________,responsible for growth-cells become keratinized and die

• Part appears pink due to vascularization in dermis• ___________________ appears white

Free edge Nail matrix

lunule

E.Homeostatic imbalances of skin

• 1) Infections and Allergies– ___________________________-fungal,itchy

red ,peeling skin(tinea pedis)

– Boils and Carbuncles-inflammation of hair follicles and sebaceous glands—often dorsal neck.Carbuncles are caused by bacteria-esp. Staphylococcus aureus

Athlete’s foot

– _____________________-small fluid filled(fever blisters)-itch and sting –caused by a herpes simplex virus-can be activated from dormancy from emotions,fever,UV light-usually around lips or oral mucosa

– _____________________________-itchy,red,swelling and turns into blisters-exposure to chemicals like poison ivy

Cold sores Contact dermatitis

– ___________________-pink,water-filled raised lesions around nose and mouth;w/yellow crust;caused by Staphylococcus

– _____________________-chronic overproduction of cells w/ red epidermal lesions—probably autoimmune

impetigo psoriasis

2-burns-tissue damage and cell death caused intense heat,electricity,UV light or certain chemicals---This can

have a domino effect on several organ systems

• destroys cells• Life threatening from 1) loss of fluids as they seep

from burned surface-dehydrating and fluid imbalance-could shut down kidneys and cause circulatory shock

• ___________________________-divides body into 11 areas,ea. 9% of total body surface area+ area around

genitals-determines % burned

• 2) infection later is a leading cause of death-after 24 hrs.,pathogens invade the area and multiply quickly

RULE OF NINES

Classification:

• 1st degree-only epidermis is damaged-red and swollen

• 2nd degree injury to epidermis and upper dermis-regrowth will occur

• 1st and 2nd degree are ___________________________burns

• 3rd degree-destroys entire thickness of skin(full-thickness burns)

Partial-thickness burns

• Critical if a) over 25% covered w/ 2nd degree b) over 10% 3rd degree OR c) 3rd on face ,hands or feet

3-Skin Cancer

– Most neoplasms benign(ex-wart)– Affect 1/5 americans– _________________________________-least

malignant and most common-affects stratum basal so cannot form keratin;boundary between epidermis and dermis lost;fairly slow growing

– _______________________________-from stratum spinosum-scalp,ears,hands-grows rapidly,but if caught early,prognosis is good

Basal cell carcinoma

Squamous cell carcinoma

– ____________________-cancer of melanocytes(5%of skin cancers)-happen where ever there is pigment and often deadly-50% survival w/early detection

– ABCD RULE_• a)asymmetry• b)border irregularity• c)color-areas of different color• d)diameter-larger than 6 mm

Malignant melanoma

Take notes p. 127 on developmental aspects:

• Lanugo-downy hair covering on infant –shed by birth

• Newborn has vernix caeosa-white and cheesy and made by sebaceous glands-protection while in womb

• Newborn skin thin-milia-accumulations in sebaceous glands(nose and forehead)

• Skin and hair more oily during adolescence-acne occurs

• Dermatitis-inplammation

• During old age- subcutaneous tissue decreases-less tolerance to cold/also drier due to less oil/decreasing elasticity/thinning of skin and more bruising

• Good nutrition,fluids and cleanliness csn slow loss of elasticity-aggravated by sun and smoking

• Hair loses luster and less hair follicles

• ALOPECIA-hair thinning and baldness

• Male pattern baldness-has light vellus hairs

• Graying hair

• Genetic factor-as gene is expressed,melanin in hair decreases

• Also genetic factor in baldness