Ch 4 Skinandbodymembranes 090708124657 Phpapp01
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Transcript of 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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I. Classification of Body
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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I. Classification of Body
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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I. Classification of Body
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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I. Classification of Body
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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I. Classification of Body
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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II. The Integumentary System
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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II. The Integumentary System
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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II. The Integumentary System
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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II. The Integumentary System
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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II. The Integumentary System
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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II. The Integumentary System
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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II. The Integumentary System
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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II. The Integumentary System
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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II. The Integumentary System
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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III. Appendages of the Skin
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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III. Appendages of the Skin
Sweat GlandsSudoriferous glands
Can be as many as 2.5 million per person
Two types
Eccrine
Apocrine
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III. Appendages of the Skin
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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III. Appendages of the Skin
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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III. Appendages of the Skin
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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III. Appendages of the Skin
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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III. Appendages of the Skin
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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III. Appendages of the Skin
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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III. Appendages of the Skin
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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III. Appendages of the Skin
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 .