Chpt. 4 Notes

Body membranes

covers surfaces, line body cavities, and form protective sheets around organs

body membranes groups

epithelial and connective tissue

epithelial membranes

cutaneous, mucous, serous

connective tissue membrane

synovial

cutaneous membrane

skin; keratinizing stratified squamous epithelium and dense connective tissue (dermis); dry membrane

mucous membrane

epithelium tissue on loose connective tissue; lines cavities open to exterior; refers to only location of membrane not cellular make-up; either stratified squamous or simple columnar; wet membrane to protect and lubricate

serous membrane (serosa)

Thin, double-layered membranes; covers ventral body cavity and organs; simple squamous on areolar; lines closed body cavities; occur in pairs of parietal layer and visceral layer; separated by serous fluid; names depend on location

parietal layer

lines a specific portion of the wall of the ventral body cavity for serous membrane

visceral layer

covers the outside of the organs in that cavity for serous membrane

serous fluid

allows organs to slide easily without friction

peritoneum serous membrane

lining of the abdominal cavity/organs

pleura serous membrane

lines the lungs

pericardium serous membrane

lines the heart

synovial membrane

soft areolar tissue; lines fibrous capsules around joints,, bursae, and tendon sheaths; provides smooth surface and secretes lubrication and cushions organs during activity

integumentary system

includes skin and derivatives to make up a complex set of organs that have served many functions but mainly protection

Skin

tough and pliable allowing it to take constant punishment; keeps water/molecules in or out of body

skin functions

insulates/cushions, protects from damage/radiation/desiccation, heat loss regulation, mini-excretory system, Vitamin D synthesis, and cutaneous sensory receptors.

skin structure

epidermis (outer) and dermis (inner) layers connected by basement membrane

epidermis

outer layer, stratified squamous epithelium, can become keratinized

dermis

underlying layer of dense connective tissue

subcutaneous layer

deep to dermis, adipose, anchor of skin; functions as shock absorber and insolation from extreme temps

4 cells types of epidermis

keratinocytes, melanocytes, merkel cells, langerhans cells

keratinocytes

majority of cells in epidermis; produces keratin; areas of great friction have increased cell and keratin production; persistent friction causes epidermis thickening

keratin

fibrous protein that gives epidermis protective properties

melanocytes

spider-shaped epithelial cells; produce melanin; melanin granules form on sunny side of cell to protect nucleus

langerhans cells

star shaped cells arises from bone marrow; called epidermal dendritic cells; are macrophages aiding in activating immune system; 1st line of defense after pathogens enter the skin

merkel cells

present at epidermal/dermal junction; spiky shaped hemisphere; works closely with disk-like sensory ending; combination known as a merkel disk and functions as sensory receptor for touch

layers of epidermis

varies in thickness; stratum basale, stratum spinosum, stratum granulosom, stratum lucidum, stratum corneum

thick epidermis

covers palms, feet soles, and finger tips

thin epidermis

covers rest of body; stratum lucid is absent and other stratum are thinner

stratum basale

deepest epidermal layer; closest to dermis and cells get nutrients from dermis diffusion; single row of cells represents youngest keratinocytes; also known as stratum germinativum bc it's constantly doing cell division

stratum spinosum

several layers thick, keratinocytes flatten and appear irregular in shape causing it to be named prickle cells; langerhans cells are most abundant; aids in activating immune system to protect basal layer

stratum granulosum

keratinocytes change drastically, flattening and begin to disintegrate; accumulate lamellate granules; keratinocytes toughen up with plasma membranes thickening and lipids coat external surface

lamellate granules

contain waterproofing glycolipid and major factor in slowing water loss across epidermis

why do keratinocytes toughen up?

it makes them more resistant to destruction making the outer strata the strongest skin region

stratum lucidum

only occurs where skin is hairless and extra thick; cells are dead because of constant accumulation of water repellant keratin and is unable to get nutrients and o2 as they move farther from dermis/blood supply

stratum corneum

outermost layer (20-30 cell layer thick); shingle like cell remnants of layer completely filled with keratin; often called horny cells; abundance of keratin allows durable body overcoat

durable body overcoat

protect deeper cells from hostile external environment (air), from water-loss, and helps body resist from bio/chem/physical assaults.

melanin

pigment that ranges in color from yellow to brown to black; produced by melanocytes in stratum basale; exposure to sunlight stimulates melanin production; stratum basale cells phagocytize the pigment as it accumulates within the cells forming protective umbrella around nucleus to keep away UV rays

Dermis

your "hide" (corresponds to animal hides), strong stretch envelope (weird way to say covering but ok...) that helps hold body together, varies in thickness, sages and wrinkles with age bc of decrease in fibers

thick dermis

palms of hands, soles of feet, fingertips

thinest dermis

eyelids

major 2 layers of dermis

papillary and reticular

papillary layer

upper dermal region, uneven with dermal papillae which indent epidermis

dermal papillae

fingerlike projections of dermis, may contain capillary loops to furnish nutrients to epidermis, has pain and touch receptors, functions on thick areas to increase friction and enhance gripping. Creates our fingerprint.

Reticular layer

deepest skin layer (80%), contains blood vessels, sweat/oil glands, and deep pressure receptors, numerous phagocytes found in layer to prevent bacteria going deeper into the body

3 functions of the dermis

toughness, hydration and elasticity

skin color is determined by

amount/kind of melanin, amount of carotene in stratumcorneum/subcutaneous tissue, and amount of 02 going to hemoglobin

carotene

orange-yellow pigment found in carrots and other leafy green/orange-yellow veggies

hemoglobin

pigment found in RBC in dermal blood vessels

cyanosis

bluish color of skin due to poor 02 in blood

redness/erythema

indicators of embarrassment, fever, hypertension, or allergy reaction

Pallor (blanching)

certain emotional stress can cause paleness, or signify anemia, low BP, or impaired blood flow to area

Jaundice (yellow cast)

abnormal yellow skin tone caused by liver disorder where yellow bile pigments build up in blood and goes into the tissue

Bruises

reveals sights where blood has escaped circulation and clotted in tissue spaces, clotted masses known as hematomas

4 appendages of skin

sweat glands, oil glands, hair and fair follicles, nails

cutaneous glands

all exocrine, found in dermis

2 types of cutaneous glands

oil glands (sebaceous) and sweat glands (sudoriferous)

sebaceous (oil) glands

found everywhere except for palms and soles, secretes sebum substance

sebum (oil)

a mix of oil and cell fragments

sebum functions

soften/lubricates hair and skin, prevents brittle hair, impedes water loss from skin, acts as bacteria killing agent.

Sweat (sudoriferous) glands

everywhere on skin except for nipples and some external genitalia parts, over 2.5 million sweat glands per person

2 types of sweat glands

eccrine and apocrine

eccrine glands

produce sweat, which is 99% water and the rest are salts, vitamin c, metabolic wastes, and lactic acid, found all over the body, helps with body heat regulation, and secretes sweat when in a hot environment or internal temp it high

appocrine glands

mostly in axillary and genital areas, larger than eccrine glands and empty into hair follicles, secrete true sweat, fatty acids and proteins. Secretion is odorless until skin bacteria decomposes protein and fatty acids causing BO (stinky odor)

hair and hair follicles minor protective functions

prevents head trauma, eyelashes shields eyes, nose hair keeps dust/particles out of upper respiratory tract

structure of hair

flexible, produced by hair follicles with hard, fused keratinized epithelial cells

2 regions of hair

shaft and root

hair shaft

projects from skin

hair root

impeded in skin

Hair bulb matrix

well nourished epithelial cells where mitosis occurs allowing hair growth

hair color/pigment

comes from hair melanocytes and varies from different melanin types to create hair color

hair texture

determined by hair shaft shape

flat and ribbon like hair shaft

kinky hair

oval hair shaft

wavy hair

perfectly round hair shaft

straight hair

hair follicle layer

inner epidermal sheath and outer dermal sheath

hair follicles

2 distinct layers, papillae gives blood to matrix, is slanted

arrector pili muscle

small, smooth muscle cells that connect hair follicle to dermal issue, when contracted it pulls follicle into upright position, dimpling skin and creates goosebumps

Distribution/growth of hair

scattered everywhere but lips, nipples, parts of external genitalia, and thick skin area

nails

Scale like modifications of the epidermis, provides clear and protective covering on distal parts of fingers/toes, appears pink because of rich capillary beds in dermis

]free edge, body, root, nail folds, eponychium (cuticle), root

Homeostatic Imbalances of Skin

most common come from allergies, bacteria, viral or fungal infections, less common and more damaging are burns and skin cancer

athlete's foot (tinea pedis)

itchy, red, peeling condition of the skin between the toes, resulting from fungal infection

boils and carbuncles

inflammation of hair follicles and sebaceous glands on neck

cold sores (fever blisters)

Fluid filled blisters that itch and sting caused by herpes simplex infection, localized in cutaneous nerve and is dormant until activation by upset, fever, or UV radiation, occurs around lips and in mouth

contact dermatitis

itching, redness, and swelling of skin leading to blisters, caused by skin exposure to chemicals provoking allergic responses

impetigo

pink, water-filled, raised lesions that develop a yellow crust and eventually rupture, caused by highly contagious staph infection

psoriasis

chronic condition characterized by reddened epidermal lesions covered with dry, silvery scales, cause is unknown

burns

tissue damage and cell death caused by heat, electricity, UV radiation, or chemicals

2 life threatening problems with burns

1. loss of body fluids (dehydration)
2. microbial infections

Dehydration

leads to electrolyte imbalance causing shutdown of kidneys and circulatory sock

microbial infections

bacteria and fungi multiply rapidly on dead tissues and immune system becomes depressed within 1-2 days after severe burn

1st degree burn

only epidermis is damaged, area is red and swollen, heals within 2-3 days, ex. sunburn (classified as partial-thickness burns)

2nd degree burn

epidermis and upper dermis is damaged, skin is red, painful and has blisters, epithelium can regrow (classified as partial-thickness burns)

3rd degree burn

entire thickness of the skin is damaged, burned areas is blanched or blackened, not painful due to nerve endings being destroyed, regeneration isn't possible and requires skin grafts. (classified as full-thickness burns)

burns considered critical if

- Over 25% of body has 2nd degree burns
- Over 10% of body has 3rd degree burns
- There are 3rd degree burns on face, hands or feet

Facial burns are extremely dangerous because

Respiratory passages could swell cause breathing problems

rules of nines

indirectly estimated volume of fluid loss by determining total body surface burned

skin cancer

most skin tumors are benign and don't spread, some are malignant and do spread, is the most common type of cancer in humans, cause is unknown but risk factor is overexposure to UV rays.