3.2.b. Tegumentary System Skin

8/8/2019 3.2.b. Tegumentary System Skin

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TegumentarySystem:

The skin


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Skin

The skin is considered the largest organ of thebody, its extension could be of 1.6 squaremeters.2 3

It forms a protective and flexible shield allover the body.1

It has many different functions: inthermoregulation, protection against

infecctious agents and UV rays, metabolicfunctions, secretion and sensation (pain, heat,texture, etc.) 2

1 Higashida. Ciencias de la Salud Mc. Graw Hill, 2001

2 Bronson Merki, Merki. Salud una gua para el Bienestar McGraw Hill, 2003

3 Pruitt, Crumpler, Prothrow-Stith, Salud: destrezas para el bienestar, Prentice Hall, 2000


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Skin

The skin is divided into two mainregions, the epidermis, and thedermis, each providing a distinct rolein the overall function of the skin.

The dermis is attached to an

underlying hypodermis, also calledsubcutaneous connective tissue,which stores adipose tissue

2 Bronson Merki, Merki. Salud una gua para el Bienestar McGraw Hill, 2003


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Epidermis The epidermis is themost superficial layer ofthe skin and providesthe first barrier ofprotection from theinvasion of foreignsubstances into thebody.

The principal cell of theepidermis is called akeratinocyte. 1,2

EpidermisEpidermis

1 Audersirk T., Audersirk T., Byers B. Biologa, Ciencia y naturaleza Pearson, Prentice Hall, 2004

Audesirk Audesirk Byers Sixth Ed.Audesirk Audesirk Byers Sixth Ed.Biology Life on earth, Instructions Resource CDBiology Life on earth, Instructions Resource CD--ROM, 2002 Prentice HallROM, 2002 Prentice Hall

2 http://www.meddean.luc.edu/lumen/MedEd/medicine/dermatology/melton/skinlsn/sknlsn.htm


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Epidermis The deeper dead cells are pushed to the

surface by newly forming cells,

the dead cells gradually break apart and are

lost, a process called desquamation. This dead cells contain a substance callKeratin, which is a protein that confersresistance and impermeability to the skin

Desquamation constantly occurs: every timeyou shower, rub your skin or , scratch it3



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Epidermis

Some cells from the epidermis produce a darkbrown substance known as melanin

Melanin is a protein and an important factorto determine skin coloration

The more melanin is secreted, the darker theskin gets

Sun light stimulates the production of melanin, causing tanning 3



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Dermis It is found immediatelybelow the epidermis

It is attatch toconnective tissue, whichstores adipose tissue 4

The dermis containsmostly fibroblasts whichare responsible forsecreting collagen,

elastin and groundsubstance that givethe support andelasticity of the skin 3

EpidermisEpidermis

DermisDermis

Audesirk Audesirk Byers Sixth Ed.Audesirk Audesirk Byers Sixth Ed.Biology Life on earth, Instructions Resource CDBiology Life on earth, Instructions Resource CD--ROM, 2002ROM, 2002Prentice HallPrentice Hall




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Dermis

It is irrigated by smallvessels and arteries

The vasculature isorganized so that byincreasing (bycontraction) ordecreasing (by

expansion) bloodflow, heat can eitherbe conserved ordissipated 4

ArteriolaArteriola

VenulaVenula

EpidermisEpidermis

DermisDermis


Audesirk Audesirk Byers Sixth Ed.Audesirk Audesirk Byers Sixth Ed.Biology Life on earth, Instructions Resource CDBiology Life on earth, Instructions Resource CD--ROM, 2002 Prentice HallROM, 2002 Prentice Hall


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Dermis

The dermis isimportant in giving theskin its overall

strength andelasticity, as well ashousing otherimportant epithelialderived structures

such as sweat andsebaceus or oilyglands and hairfollicles. 1,2


2 http://www.medterms.com/script/main/art.asp?articlekey=3649


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Dermis

Hair Follicles.-A sac from which a hair grows

and into which the sebaceous (oil) glands open

Sweat Glands.- secrete aqueous substances

that cool the skin and excrete substances likeurea and salt

Sebaceous Glands.- secrete an oily substance

that lubricate skin and makes it impermeable

Muscle tissue.- responsible for contracting and

erecting the hair depending on nervous stimulus

like cold, aggression, phobia, etc... 4

2 http://www.medterms.com/script/main/art.asp?articlekey=3649


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SKIN DISEASES


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Skin diseases

Acne

Skin burns (1st, 2nd and 3rd degree)

Skin Cancer


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Acne Localized skin inflammation as a result of over

activity of the oil glands at the base of hairfollicles.

Acne happens when oil (sebaceous) glandscome to life around puberty, when these glandsare stimulated by male hormones that areproduced in the adrenal glands of both boys andgirls.

The oil glands, which are located just beneaththe skin, continuously produce and secrete oil

through openings in the skin. Under certaincircumstances, cells that are close to theopenings of the oil glands block the openings.This causes a buildup of oil underneath the skin.

http://www.medterms.com/script/main/art.asp?articlekey=2117


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Acne

Bacteria, which live in everyone's skin butgenerally mind their own business, feast onthis oil, multiply, and cause the surroundingtissues to become inflamed.

If the inflammation is right near the surface,you get a pustule; if it's deeper, a papule(pimple); deeper still and it's a cyst.

If the oil breaks though to the surface, theresult is a " whitehead."

If the oil becomes oxidized (that is, acted onby oxygen in the air), the oil changes fromwhite to black, and the result is a"blackhead."



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Acne


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Acne causes

Hormonal (specially in puberty)

Overproduction of dead cells

Bacteria

Hereditary

Menstrual periods The use of some cosmetics



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Miths about Acne

It is caused by a lack of hygiene...

It is caused by eating chocolate,

peanuts, pizza....

Acne only happens during youth....

www.virginexperiencedays.co.uk/experiences/ul...

www.theworldwidegourmet.com/.../ pasta/pizza.htm

www.boots.com/shop/category.jsp?classificatio...


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To reduce acne and its damage to

your skin, follow these tips:

Choose a cleanser specially formulated for acne.These products often contain salicylic acid or benzoyl

peroxide, which help to clear acne sores.

Clean your face gently, as trauma to the acne

breakouts may worsen the acne or cause scarring.When washing your face, use your hands, as any

terrycloth or other scrubbing material may cause

acne sores to rupture.

When you sleep at night, make sure you are sleeping

on a clean pillowcase and that you are the onlyperson using your pillowcase. Pillowcases absorb

traces of oil during the night, and can aggravate

breakouts if not changed regularly.



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To reduce acne and its damage to

your skin, follow these tips:

If you have longer hair, make sure to pull it backwhen you sleep at night. The oil in your hair can

aggravate your skin as well. If you need to use a moisturizer, use only light, non-

comedogenic moisturizers, which do not aggravateacne. There are oil-free moisturizers on the marketthat contain anti-bacterial agents for acne-prone skin.

This type of product may be your best option. If you are a woman, use an oil-free foundation. Heavy

makeup or other cosmetic products that block poresmay cause a flare-up of acne.



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SKIN CANCER...

http://www.cs.wright.edu/~agoshtas/fig8.jpg


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What is Skin Cancer?

Skin cancer is a disease in which cancer

(malignant) cells are found in the outer layers

of your skin There are several types of cancer that start in

the skin. The most common are basal cell

cancer and squamous cell cancer,

Skin cancer is more common in people with

light colored skin who have spent a lot of time

in the sunlight.

http://www.maui.net/~southsky/introto.html#is


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FACTS.... Skin cancer can occur anywhere on your

body, but it is most common in places thathave been exposed to more sunlight, such asyour face, neck, hands, and arms.

Skin cancer can look many different ways. The

most common sign of skin cancer is a changeon the skin, such as a growth or a sore thatwon't heal. Sometime there may be a smalllump. This lump can be smooth, shiny andwaxy looking, or it can be red or reddish

brown. Skin cancer may also appear as a flatred spot that is rough or scaly. Not all changesin your skin are cancer, but you should seeyour doctor if you notice changes in your skin.



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What causes skin cancer? Very simply, sunburn and UV light can

damage your skin, and this damage can leadto skin cancer.

There are of course other determining

factors, including yourheredity and theenvironment you live in.

However, both the total amount of sunreceived over the years, and overexposure

resulting in sunburn can cause skin cancer.Most people receive 80% of their lifetimeexposure to the sun by 18 years of age.



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Risk Factors and Skin

Cancer Tanning is your skin's response to UV

light. It is a protective reaction to

prevent further injury to your skin fromthe sun. However, it does not prevent

skin cancer.

If there is a history of skin cancer inyour family, you are probably at a higher

risk.



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Sun light and UV rays...

The level of UV light today is higher than itwas 50 or 100 years ago. This is due to a

reduction ofozone in the earth's atmosphere Ozone serves as a filter to screen out and

reduce the amount of UV light that we areexposed to.

Other influencing factors include elevation,latitude, and cloud cover. Ultra Violet light isstronger as elevation increases, also in theequator, and it is lower if it is cloudy



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Melanoma Melanoma is a disease of the skin in which

cancer (malignant) cells are found in the cellsthat color the skin (melanocytes).

Melanoma usually occurs in adults, but it mayoccasionally be found in children andadolescents.

Melanoma is a more serious type of cancer thanthe more common skin cancers, basal cell canceror squamous cell cancer, which begin in thebasal or squamous cells of the epidermis

Like most cancers, melanoma is best treatedwhen it is found (diagnosed) early. Melanomacan spread (metastasize) quickly to other parts ofthe body through the lymph system or throughthe blood.



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HowTo Spot Melanoma

Since early detection greatly improves one'schances of surviving melanoma, you should

examine your skin every six to eight weeks. The best time to do this is after a bath or

shower, standing in front of a full-lengthmirror. Use a hand-held mirror to help youview areas that are difficult to see.

Examine all moles or markings and look forany changes in the number, size, shape orcolor of these markings

www.cancerresearch.org/melanomabook.html


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A = Asymmetry: Melanoma lesions

are typically irregular in shape

(asymmetrical); benign

(noncancerous) moles are typicallyround (symmetrical).

B = Border: Melanoma lesions

often have irregular borders (i.e.,

ragged or notched edges); benign

moles have smooth, even borders. C= Colors: Melanoma lesions

often contain many shades of

brown or black; benign moles are

usually a single shade of brown.

D =Diameter: Melanoma lesions

are often more than 1/4 inch or six

millimeters in diameter (about the

size of a pencil eraser); benign

moles are usually less than 1/4

inch or six millimeters in diameter.www.cancerresearch.org/melanomabook.html


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How to reduce the risk of sunburn

and skin cancer...

Minimize yourexposure to the sun at middayand between the hours of10:00AMand 3:00PM.

Apply sunscreen with at least a SPF-15orhigher, to all areas of the body which are

exposed to the sun. Reapply sunscreen every two hours, even on

cloudy days. Reapply after swimming orperspiring.

Wearclothing that covers your body andshades your face. (Hats should provide shadefor both the face and back of the neck.)

Avoid exposure to UV radiation from sunlampsor tanning parlors.


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3.2.b. Tegumentary System Skin