THE INTEGUMENTARY SYSTEM Disorders and Functions

http://www.youtube.com/watch?v=MeTaBniB0ok

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THE STRUCTURE OF THE SKIN The skin(cutaneous

membrane) is the largest  Organ and covers the entire surface of the body.

It is comprised of all 4 tissue types epithelial, connective, muscle, and nervous tissue.

The skin has 2 regions, the epidermis and the dermis. There is also the hypodermis that is found between the skin and anything underneath, usually muscle. If there is no muscle, the hypodermis will attach directly to the bone. Ex: there are flexion creases where the skin attaches directly to the joints of the fingers. Stratum

EPIDERMIS

EPIDERMIS STRATUM BASAL: The epidermis is made

up of stratified squamous epithelium divided into 5 separate layers. From the bottom up, the layers are

      

1.       Divides and produces new cells that are then pushed to the surface

一 .  As they move farther from the dermis, they die from lack of nutrients and eventually fall off

2.       Has macrophages that phagocytizes microbes that travel to lymphatic organs to stimulate the immune system

- (Macrophage: a type of white blood cell) 3.       Melanocytes produce melanin

-The amount of melanocytes are the same in everyone. What determines skin color is the amount of melanin, and its distribution.

Example: The melanocytes will produce more melanin to protect the skin from the rays of the sun

CONTINUED… 4.       Albinism- the inability to

create melanin

5.       There are also nerve endings near this layer to supply temperature and pain sensation to the brain

·         Stratum Spinosum ·         Stratum granulosum ·         Stratum lucidum

1.           A thick layer that creates calluses

2.           Forms in areas of constant friction (palms, soles of the feet, elbows)

·        

Stratum Corneum 1.       Cells pushed to the

surface become flat and hard

2.       Hardening is because of the formation of Keratin

一 .  Keratin- a fibrous waterproof protein

3.       Protects body from water loss and water gain

The epidermis has no blood vessels; tightly packed cells

EPIDERMIS

DERMIS · Composed of dense irregular connective tissue.       Has finger like projections called dermal

papillae(responsible for fingerprints) that anchors the epidermis

1. To increase friction and provide a better gripping surface

   Contains collagen fibers that keep the skin from

tearing apart

ACCESSORY STRUCTURES OF THE SKIN

Hair Nails Glands All of epidermal origin

HAIR Found on all body parts except palms, soles of

feet, lips, nipples, and portions of external reproductive organs

Hirstism- excessive body/facial hair Hair follicle- Hairs project from these complex

structures Alopecia- hair loss Arrectorpili- Smooth muscle that attaches to

the follicle that causes the hair to stand on end. “Goose bumps”

GLANDS Produce and secrete

substances

Sweat Glands (Sudoriferous glands): all regions of the body. Example- excrete through exocytosis.

Apocrine glands: Open into follicles in the anal region, groin, and armpits. Begin at puberty.

Acne Vulgaris: Inflammation of sebaceous glands.

Mammary Glands: Modified apocrine sweat glands that produce milk only after childbirth.

Exocrine Glands: Open onto surface of skin. Become active in heat. Secretes mostly water and waste.

Ceruminous Glands: Secrete earwax.

Sebacious Glands: Lubricate hair and skin as well as weakens or kills bacteria on skin.

DISORDERS OF THE SKIN The skin is subject to many disorders, some more life threatening than others.

Athlete’s foot- Caused by a fungal infection, usually involves the skin of the toes and the soles.

Impetigo- A highly contagious disease occurring mostly in small children.

Psoriasis- A chronic condition, possibly hereditary, in which skin develops pink/reddish patches covered by silvery scales due to overactive cell division.

Eczema- Inflammation of the skin, caused by sensitivity to various chemicals.

Dandruff- A skin disorder caused by an accelerated rate of keratinization in certain areas of the scalp.

Urtiraria- Hives, caused by an allergic reaction.

SKIN CANCER Characterized as

either melanoma or non-melanoma.

Non-melanoma cancers are much less likely to metastasize.

Non-melanoma cancers include Basal cell carcinoma Squamous cell

carcinoma

Basal cell carinoma(non-melanoma) is the most common.

Is caused by UV radiation causing epidermal basal calles to form a tumor while suppressing the immune system’s ability to detect the tumor.

95% of patients cured by removing the tumor

SQUAMOUS CELL CARINOMA Begins in the epidermis More likely to spread to nearby organs 1% of cases are deadly Also triggered by UV exposure

MELANOMA More likely to be malignant. Starts in melanocytes, usually appears

in males. More common in fair-skinned people,

especially those with sunburns as a child.

62,000 new cases each year.

WOUND HEALING Injury to the skin cause an inflamatory response.

(Example: redness, swelling, heat, pain) Fibroblasts bring about scar formation.

BURNS -An epidermal injury caused by heat. -Two factors affect burn severity:

1. Depth of burn(can be classified by degree) 2. Extent of the burn area(can be estimated by of 9’s)

THE EFFECTS OF AGING ·As you get older, the dermis becomes thinner and the epidermis is

held less tightly and the skin loosens

·The adipose tissue in the hypodermis of the face and hands decrease1.       The elderly are more likely to feel cold

     There is less collagen, and the fibers within the dermis become

coarser, thicker, and farther apart ·         The skin becomes wrinkled because 1.       The epidermis is loose 2.       There are less fiber, and the ones that do remain are

disorganized 3.       The hypodermis has less padding ·         There are fewer blood vessels, less sweat glands, and the

numbers of hair follicles decrease. ·         The number of melanocytes decreases causing hair to turn gray

On the next slide, there is a list of 12 functions of the skin. Whoever can name 6 of them, gets 10 bonus points on the classwork!!!

H O M E O S T A S I S Hypothermia- Below normal temperature; Hyperthermia- above normal

temperature

Skin forms protective layer over entire body Melanocytes protect from UV radiation Dead skin cells protect from bacterial invasion Helps regulate water loss Assists the function of the urinary system(sensible/insensible perspiration) Plays minor role in waste elimination Produce Vitamin D Useful to digestive and skeletal system Only small amount of UV radiation is needed Gather sensory information- specialized for touch, pain, heat(associated

with nervous system) Fingertips- greatest number of receptors Helps regulate body temperature

THE END !!!!!