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8/3/2019 Ch 4 Skinandbodymembranes 090708124657 Phpapp01

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Skin and Body Membranes

Human Anatomy and Physiology

Mr. McCammon


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I. Classification of Body

Membranes Epithelial Membranes include the cutaneous

membrane (skin) and the mucus

membranes, and the serous membranes.

Always combined with an underlying layer

of connective tissue.

Thats why it is considered an organ.


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Membranes Cutaneous Membrane

This is your skin.

Composed of keratinizing stratified squamous

epithelium.

Underlying dermis is dense (fibrous)

connective tissue. Exposed to air and is dry.


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Membranes Mucous membranes (or mucosa)

composed of epithelium (the type varies from

site to site) resting on a loose connective tussemembrane called a lamina propria.

Lines all the cavities that open to the exteriorsuch as respiratory, digestive, urinary, and

reproductive tracts. Always moist because they are continually

bathed in secretions.


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Membranes Serous Membranes (serosa)

Layer of simple squamous epithelium restingon a thin layer of areolar connective tissue.

Line the body cavities that are closed to theexterior (except for the dorsal body cavities and

joint cavities)

Occur in pairsparietal layer lines a specificportion of the wall of the ventral body cavityand folds in on itself to form the viseral layerwith covers the outside of the organs in thatcavity.


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Membranes The serous layers are separated by a clear

fluid called serous fluid.

Important to decrease friction by movingorgans (heart, stomach)

Some serous membranes

Peritoneumabdominal cavity Pleuraaround the lungs

Pericardiumaround the heart


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Membranes Synovial membranes are composed of

connective tissue and contain no epithelialcells at all.

Line the fibrous capsules surrounding jointswhere they provide a smooth surface andsecrete a lubricating fluid.

Contain small sacs of connective tissuecalled bursae and tubelike tendon sheathsboth cushion organs moving against each

other during muscle activity.


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II. The Integumentary System

The Skin

Includes cutaneous membrane, sweat and oil

glands, hairs, and nails

External body covering

Keeps water and other molecules in the body.

Keeps and other things out Pliable yet tough


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II. The Integumentary System Study chart on page 95.

The structure of the skin.

Epidermis

Stratified epitheliumbecomes keratinizing

(hard and tough)

Dermis

Dense connective tissue

Both connected tightly until a burn or

friction causes a blister.


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Deep down in the skin is the subcutaneous

tissue or hypodermis

Basically adipose tissue

Not considered part of this skin, but does

anchor the skin to the underlying organs.

Shock absorber and protected from temperaturechanges.

Makes you curvy


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II. The Integumentary System KNOW THE DIAGRAM ON PAGE 96.

The Epidermis in Detail

5 zones (layers) called strata

In order, basale, spinosum, granulosum, lucidum,

corneum. They are avascular

Most cells are keratinocytes (produce fibrousprotein that makes the epidermis tough.

Deepest layer is stratum basale lies closes to thedermis and contains the only cells that receiveadequate nourishment via diffusion from thedermis.


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Cells from the stratum basale are constantlydividing and pushed up to become part of

the epidermis. Stratum lucidum only occurs where the skin

is hairless and extra thick (palms, feet)

Stratum corneum makes up of our body. Constant replacedNew epidermis every

25-45 days.


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Melaninyellow to brown pigment isproduced by cells called melanocytes foundin the stratum basale.

Sunlight stimulates melanin productioncauses tanning.

Melanin forms a protective shield from

sunlight so it doesnt affect genetic material. Freckles and moles are where melanin is

concentrated in one spot.


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II. Integumentary System

Excessive exposure can lead to skin cancer.

It can cause the elastic fibers to clump and

lead to leathery skin.

Black people seldom have skin cancer

because melanin is an effective shield

against it.


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The Dermis

Your hide strong, stretchy envelope

that helps to hold the body together.Leather goods are just treated dermis ofanimals.

Two regionsPapillary layer

reticular layer


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The Papillary Layer is the upper dermalregion

Uneven with finger like projections calleddermal papillae

Contain capillary loops which nourish theepidermis

Pain receptors touch Meissners corpuscles. On hands and feet papillae are arranged in

patterns to enhance gripping ability.


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Reticular layer

Deepest layer

Contains seat, blood vessels, sweat and oilglands, deep pressure sensors called Paciniancorpuscles

Collagen and elastic fibers make it tough

Restrictions of blood in the dermis results incell death and causes Decubitus ulcers(bedsores)


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Skin Color

The amount and kind of melanin in the dermis

The amount of carotene deposited in thestratum corneum (carotene is an orange yellow

pigment

The amount of oxygen bound to hemoglobin(pigment in red blood cells)


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People with lots of melanin have brown-toned skin.

Light skinned people (caucasian) peoplehave less melanin and have a crimson colordue to oxygen-rich blood.

Then hemoglobin is poorly oxygenated theskin can become blue (cyanosis)commonduring heart failure and breathing disorders


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Skin color Redness or erythemamay indicate

embarrassment (blushing), fever, hypertension,

inflammation, or allergy.

Pallor or blanchingbecoming palefear,

anger, stress, anemia, low blood pressure,

impaired blood flow

Jaundice or yellow castliver problems Bruises or black-and-blue markssites where

blood has escaped from circulation and has

clotted in the tissue spacescalled hematomas


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III. The Appendages of the

Skin Cutaneous glandsall exocrine glands that

release their secretions to the skin surface

via ducts. Two groups

Sebaceous glands

Sweat glands

Form in Stratum basale but push lower intothe dermis


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III. Appendages of the Skin

Sebaceous (oil) glandsfound all over thebody except palms of hands and feet.

Most open onto a hair follicle, but someopen directly onto the skin.

Sebum is the name of the oilmixture ofoil and fragmented cells that keep the hairand skin moist. Kills bacteria

Increase in male hormones increase sebumduring adolescence.


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If a sebaceous glands duct becomes

blocked by sebum a whitehead forms. If the

whitehead dries it becomes a blackhead. Acne is an active infection of the sebaceous

glands

Severe acne results in scarring of the skin.


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Sweat GlandsSudoriferous glands

Can be as many as 2.5 million per person

Two types

Eccrine

Apocrine


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Eccrine glands

More numerous

Produce seat

Water, salt, vitamin C, ammonia, urea, uric acid, and

lactic acid (which attracts mosquitoes)

Sweat is acidic (ph 4-6) which kills bacteria

Reaches the skin by a funnel-shaped pore.

They secrete sweat when the external or body

temperature is high.


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When the sweat evaporates, it carries heatwith it, cooling the body.

On a hot day the body can lose 7 liters ofwater per day.

A few degrees change in body temperaturecan radically alter body chemistry.Maintaining body temp. is very important tohomeostasis.


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Apocrine sweat glands are confined to the

axillary and genital areas

Larger than eccrine glands

Ducts empty into hair follicles

Secretions contain fatty acids, proteins, as

well as all the other stuff secreted by the

eccrine glands.


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III. Appendages of the Skin The secretions can have a milky or

yellowish color.

Odorless until bacterial that live on the skin

use the proteins and fats as nutrients. Thenit produces a musky unpleasant odor.

Begin to function during puberty.

A lot is unknown about these. They havealmost no thermoregulatory function.

Become more active during stress or sexualforeplay.


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There are millions of hairs scatterd all over

the body.

Only a few serve an important function

Hair on head to protect brain from bumps.

Eyelashes shielding the eyes

Nose hairs keep particles from the

respiratory tract.


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Hairs original purpose was to keep the body

warm.

Hair is produced by a hair follicle

Root hair is enclosed in the follicle.

The hair shaft extends out of the follicle.

Hair is formed by a division of the stratum

basale called hair bulb matrix.


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KNOW THE DIAGRAM OF A HAIR ON

PAGE 100

Arrector pili muscles are part of the hairfollicle that make the hair stand up and

makes goose bumps


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Nails are scalelike modifications of theepidermis that corresponds to the hoof or

claw of other animals. Each nail has a free edge, a body (visible

portion), and a root (embedded in the skin)

Each nail has overlapping edges called nailfolds.

Proximal nail fold is called the cuticle.


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Stratum basale of the epidermis extends beneath

the nail as the nail bed.

Nail matrix is responsible for nail growth. The white cresent is called the lunula.

Nail is normally clear. Pink color is due to blood

supply to the stratum basale.

When blood supply is low, nail becomes cyanotic.

KNOW THE DIAGRAM ON PAGE 102.


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IV. Homeostasis The skin has more than 1000 different

ailments.

Athletes foot itchy, red, peeling condition

of the skin between the toes resulting from afungal infection; tinea pedis

Boils and carbunclesinflamation of the

hair follicles and sebaceous glands,common on the dorsal neck. Carbuncles arecaused by bacterial infection (usuallyStaphlococcus aureus)


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IV. Homeostatis

Cold Soresfever blisterssmall fluid-filled

blisters that itch and sting, caused by a herpes

simplex infection. Localized in a cutaneous nerve,where it remains inactive until emotional upset

usually around the lips and oral mucosa

Contact dermatitisitching, redness, and swelling

of the skin, progressing to blistering. Exposure ofthe skin to chemicals the provokes an allergic

response.


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IV. Homeostatis Impetigopink, water-filled, raised lesions

of the mouth and nose that develops a

yellow crust and eventually rupture. Very

contagiouscommon in elementary schoolchildren.

Psoriasischronic condition, characterized

by reddened epidermal lesions, coveredwith dry, silvery scales. Can be disfiguring.

Cause is unknown .

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