Chapter 4 Skin and Body Membranes BODY MEMBRANES

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 mostly 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(w/sites) of epithelial tissue resting on a loose connective tissue called __________ and lines all cavities 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) -in urine w/urinary mucosa Lamina propria

• Epithelium of mucosae is adapted for absorption or secretion/most secrete mucous , but not all

3)Serous membranes(serosa)- • • Areolar connective tissue 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)

• 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 • THINK of balloon analogy! • Serous layers separated by__________-secreted by both membranes Parietal layer Serous fluid Visceral layer

• Serous fluid allows organs to slide against ea. Other and cavity w/o friction, even though membranes are very close to each other

SEROUS NAMES RELATED TO LOCATION peritoneum pleural – ___________covers abdominal cavity – __________-surrounds lungs – ____________surrounds heart pericardium

Connective Tissue membranes/synovial 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-no epithelial tissue Soft areolar connective tissue

II. The Integumentary Sysyem(skin)cutaneous membrane • The Integumentary System(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-modified cholesterol molecules convert to Vitamin D w/sunlight

• 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 keratin Cutaneous sensory receptors

Structure of skin – Epidermis-stratified squamous epithelial capable of keratinizing(hardening) – _____-underneath-mostly dense connective tissue – Epidermis and dermis strongly connected-fairly tear resistant-, but some abuse can cause them to separate—interstitial fluid comes between layers making a _______ – _______(hypodermis)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-also resposible for “curves” Subcutaneous tissue dermis blister

1)Epidermis • • • strata has 5 layers or ________. From inside out they are stratum basale, spinosum, granulosum, lucidum and corneum avascular most cells are _______________which make keratinocytes

• Stratum basale-closest to dermis and connected along a wavy borderline. Contains epidermal cells 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 thickie. 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--tough protein-protects lower cells; dandruff sloughs off from here/very protective • Shed 18 kg(~40 lbs. ) dandruff in a lifetime-food source for dust mites • 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 to make 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 melanosomes freckles

• Melanin affects production of leathery skin and depress immune system-may contribute to herpes simplex and cold sores-more likely after tanning • Epidermal dendritic cells –scattered in epidermis –alert and activate immune system to react to bacterial invasion @ epidermal junction • Merkel cells- associated w/sensory nerve endings and act as touch receptors •

2)dermis-‘hide Papillary layer Dermal papillae – strong, stretchy – dense fibrous connective tissue – __________upper dermal region; _______-peglike projections from superior-indent into epidermis- surface-many containing capillary loops-thus nutrients; some have pain receptors-__________ or touch receptors_________________ Free-nerve endings Meissner’s corpuscles

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

Reticular layer – – – 2)______________(lamellae corpuscles)-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 Pacinian corpuscles

– __________________ happen in bedridden patients not turned regularly-pressure restricts blood supply and redness when pressure is released – Rich nerve supply – Read about Botox-p. 118 Decubitus ulcers

C-Skin Color-3 pigments: • • • 1 -melanin in epidermis 2 -carotene in stratum corneum and subcutaneous tissue-orange/yellow • 3 -O 2 -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: – __________-rednessblushing, 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 bruises jaundice hematomas

D. Appendages of the Skin Cutaneous glands • • • 1 -_________________exocrine glands-release secretions to skin’s surface via ducts***formed by cells of stratum basale and push into deeper into dermis , mostly 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/also kills some bacteria/more active during adolescence sebum

• _______(sudoriferous glands)-many in the skin-2 types: 1)eccrine glands-all over body and make sweat(mostly water, Na. Cl, 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

Apocrine 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

Hair follice 3 -Hair and Hair Follicles • . • 1)Hairs –millions-/minor protective functionfilter and cushion) 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-of hair bulb)-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 • Frizz-cuticle worn away/split-ends • Hair pigments made by melanocytes in hair bulb

• 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 • oval shape yields smooth, silky and wavy 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 actually connective tissue/papilla yield blood supply to matrix in hair bulb • _______________smooth muscle that raise hair in response to temp Errector pilli

Free edge Nail matrix • 3) Nails-scalelike product of dermis(corresponds to hoof • • • lunule or claw) Each nail has a ________, a body(visible and a root(imbedded in skin) Nail folds of skin become cuticle at proximal end 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

E. Homeostatic imbalances of skin 1000’s of different skin ailments • 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 lightusually around lips or oral mucosa – _______________itchy, red, swelling and turns into blistersexposure to chemicals like poison ivy Cold sores Contact dermatitis

– __________-pink, water-filled raised lesions around nose and mouth; w/yellow crust; caused by Staphylococcus/common in children – ___________-chronic overproduction of cells w/ red epidermal lesions—probably autoimmune/triggered often by trauma, infection, hormone changes or stress • 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 (burned skin is sterile for ~ 24 hrs. ) later is a leading cause of death-after 24 hrs. , pathogens invade the area and multiply quickly RULE OF NINES

Classification: • 1 st degree-only epidermis is damaged-red and swollen • 2 nd degree injury to epidermis and upper dermisregrowth will occur/usually w/o scarring • 1 st and 2 nd degree are ______________burns • 3 rd degree-destroys entire thickness of skin(fullthickness burns) Partial-thickness burns

• Critical if a) over 25% covered w/ 2 nd degree b) over 10% 3 rd degree OR c) 3 rd on face , hands or feet/Facial burns particularly dangerous because of respiratory passages-may cause suffocation

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

• 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-inflammation

• 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 can 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