honorsPHYSIOLOGYintegumentary

8/14/2019 honorsPHYSIOLOGYintegumentary

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4 TYPES OF MEMBRANES

1) serous membranes: line body cavities that

dont open to the outside

location: thorax,abdomen & the organswithin

made of: simplesquamous epithelium +loose CT


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1) serous membranes: Pleura = serosa lining the

thoracic wall & lungs

Pericardium = serosa enclosingthe heart

Peritoneum = serosa lining

abdominopelvic cavity + viscera


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2) mucous membranes: line cavities & tubes that open to the

outside

location: oral & nasal cavities, tubesof the digestive, respiratory, urinary, &reproductive systems

made of: epithelium w/ gobletcells + loose CT

secrete: mucus


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3) synovial membranes

location: the inner linings of synovial

joint cavities made of: dense CT + loose CT +

adipose tissue

secrete: synovial fluid tolubricate joints


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4) cutaneous membranes:

Skin

Dry because it is exposed to air


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INTRODUCTION

integumentary system = skin +

accessory organs (hair, nails, sweat & oil

glands)

hyperhidrosis = a condition of profuse,

uncontrollable, unpredictable sweating


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SKIN & ITS TISSUES

skin is a large organ vital to maintaininghomeostasis

Skin stats: Surface area = 1.2 to 2.2 square meters

Weight = 9 to 11 pounds

Accounts for 7% of an adults total body

weight 1.5 to 4 mm thick in various parts of the body

Integument = covering


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functions of skin:

Protection: chemical, physical, biological

regulates body temperature

Insulation + fat storage

prevents water loss from deeper tissues


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functions of skin:

houses sensory receptors sensitive to

pain, temperature, touch, pressure

makes biochemicals such as vitamin D

excretes some waste

Blood reservoir has an extensive

vascular supply


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2 layers of skin:

epidermis = outer layer made of stratifiedsquamous epithelium


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2 layers of skin:

dermis = thicker inner layer made ofconnective & epithelial tissue, smooth

muscle, nervous tissue, blood


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2 layers of skin:

the 2 layers are separated by thebasement membrane


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a subcutaneous layer (hypodermis) made

of loose CT & adipose tissue binds the

skin to the organs under it


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EPIDERMIS:

4 layers on most of the body: stratum basale = base layer

stratum spinosum = prickly layer,keratinocytes are flatter and appear spiny

stratum granulosum = granular layer,granules form keratin in the upper layers

and provide waterproofing


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EPIDERMIS:

4 layers on most of the body: stratum corneum = horny layer

A 5th layer on only thick skin:- stratum lucidum = clear layer, can only be

found on palms & soles (thick skin), a row of

thin, flat, dead keratinocytes


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EPIDERMIS:

epidermal cells undergo keratinization asthey mature & are pushed toward thesurface

the outermost layer, the stratum corneum(horny layer), is made of dead epidermalcells which are eventually shed

40 pounds in an average lifetime! Cornu = horn

Totally new epidermis in 25-45 days!


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EPIDERMIS:

the rate of cell division increases where

skin is rubbed off regularly forming

calluses & corns

the epidermis protects underlying tissues

against water loss, injury, & the effects of

harmful chemicals


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EPIDERMIS:

melanin protects cells from the effects ofUV light

melanocytes (cells that make melanin)

transfer melanin to epidermal cells whichdetermines skin color


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SKIN COLOR:

genetically determined

varies based on the kind & amount of

melanin produced, since all people have

about the same number of melanocytes


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SKIN COLOR:

influenced by environment (exposure tosun), chemically inducedphotosensitivity (some meds, perfumes,

detergents, limes, celery) influenced by physiological factors

(blood color, diet, chemicals such asbilirubin)

3 pigments affecting skin color =melanin, carotene, hemoglobin


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DERMIS:

Composed of strong, flexible c.t.

Corresponds to animal hides used to

make leather

dermis binds the epidermis to underlying

tissues

has 2 layers: Papillary

reticular


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DERMIS:

fingerprints result from epidermal ridges

projecting inward & dermal papillae

projecting upward

genetically determined

increase friction & enhance gripping ability


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DERMIS:

dermal blood vessels supply nutrients to

all skin cells & help regulate body

temperature (vasoconstriction,

vasodilation)

the dermis also contains hair follicles,

sweat glands, & sebaceous (oil) glands


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DERMIS:

nerve fibers are scattered throughout the

dermis

some carry impulses to muscles & glands

some are associated with sensory receptors

in the skin, & they carry impulses to the brain

& spinal cord


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DERMIS:


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SUBCUTANEOUS LAYER:

made of loose CT + adipose tissues

it helps supply the skin with blood

the adipose tissue helps conserve bodyheat


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ACCESSORY

ORGANS OF THE

SKIN

hair

hairs develop in the follicles

new cells push older cells closer to the

surface where they become keratinized & die

hair color is genetically determined

an arrector pili muscle attaches to each hair

follicle & this pulls the hair erect when

stimulated = goose bumps


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Functions of hair

To sense insects on skin

Guards against physical

trauma, heat loss, sunlight

Eyelashes shield eyes nose hairs filter large particles from air


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ACCESSORY ORGANS OF THE

SKIN

sebaceous glands

holocrine glands that secrete sebum = a mix

of oil & cellular debris

sebum keeps skin & hair soft, pliable, &waterproof

acts as a

bactericide- function begins

at puberty


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ACCESSORY ORGANS OF THE

SKIN

sweat glands = sudoriferous glands

exocrine glands which consist of a coiled tube

eccrine / merocrine sweat glands respond to

elevated body temp.

apocrine sweat glands respond to pain or

emotional stress, function begins at puberty

modified sweat glands include mammaryglands & ceruminous glands in the outer ear

canal

2.5 million, most in palms, soles, forehead


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ACCESSORY

ORGANS OF THESKIN

nails protective coverings for fingers & toes

each nail consists of a nail bed + nail plate

the white moon-shaped lunula at the base ofthe nail plate is the area where cells are most

actively dividing

again, cells become keratinized & die as they

age


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Apocrine sweat gland eccrine sweat gland


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REGULATION OF BODY

TEMPERATURE

vital because heat affects the rate of

metabolic reactions heat is a product of metabolism

skin constantly loses heat to the air


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REGULATION OF BODY

TEMPERATURE

If temp is too high:

dermal blood vessels dilate

sweat glands secrete sweat

if temp is too low:

dermal blood vessels constrict

sweat glands deactivate

skeletal muscles contract involuntarily =

shivering


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HEALING OF WOUNDS

skin injuries trigger inflammation (red,warm, swollen, tender)

dividing epithelial cells fill in shallow cuts

clots close deeper cuts


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HEALING OF WOUNDS

scabs = clots + dried tissue

scars result from connective tissue

replacing skin

granulations form in large open wounds


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Wound healing


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HEALING OF WOUNDS

Wound healing can be differentiated into three majorphases Inflammatory phase (1)

The wound is rinsed by blood and filled with blood-

collagen and fibrin constituents.

Proliferative phase (2)

Resorption of blood-collagen and reepithelialization.

The reepithelialization is a movement of thesurrounding epithelial cells to close the wound.

Maturation and remodeling phase (3)

Growth of new epithelial cells.


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Homeostatic imbalances of skin:

Skin cancer

Basal cell carcinoma = least malignant & most

common 30% of all white people get it

Squamous cell carcinoma - often on scalp &hands, grows rapidly and metastasizes

Melanoma = cancer of melanocytes, most

dangerous type ABCD rule:

Asymmetry, border irregularity, color, diameter


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Burns

1st degree = epidermis is damaged

ex. sunburn

2nd degree = epidermis + part of the dermisare damaged, blisters occur

3rd degree = epidermis + dermis + hypodermis

are all damaged, nerve endings are destroyed Evaluated by the rule of nines


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Effects of aging:

1) Skin thins

2) Lubricating substances become deficient,so skin gets dry & itchy

3) Elastic fibers clump, skin loses elasticity4) Sub Q fat layer diminishes, often cold

3 & 4 cause wrinkles

5) Less melanocytes & Langerhans cellsenhance the risk of skin cancer

6) Hair thins due to fewer active hair follicles

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