Human Body Systems Unit

The Skin

Three Layers of Tissue The skin is made up of three

layers of tissues.› Epidermis, dermis, fatty layer

(subcutaneous)

Epidermis

1. Epidermis – outer, thinnest layer.a. The outermost cells are dead and water

repellent.b. New cells are produced at the base and

move up to replace ones rubbed off.

Epidermisc. Melanin – a pigment that protects your skin

and gives it color (located in the epidermis). When skin is exposed to UV rays, melanin production increases and your skin becomes darker.

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Vitiligo When melanocytes die, or do not

function properly.

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Epidermis Your skin is the largest organ of

your body. It is also your largest sensory organ.

STOP, PAUSE….Take a DEEP

BREATHYou just breathed in dead

skin cells from your neighbor! Dead dermis cells make up a large

portion of ‘dust’.

Dermis

2. Dermis – Located directly below the epidermis.

a. Contains blood vessels, nerves, muscle, oil, sweat glands, and other structures.

Fatty Layer

3. Fatty Layer – insulates body Think babies and sumo wrestlers….

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More Fatty Layers…

Fatty layers are key in terms of animal hibernation…

Types of Burns

1st Degree2nd

Degree3rd Degree

1st Degree

3rd Degree

2nd Degree

Types of Burns

1st Degree2nd

Degree3rd Degree

Major Functions Your skin carries out several major

functions.

1. Protection

Major Functions2. Sensory organs3. Formation of Vitamin D

a. Produced in presence of UV light.b. Essential for good health.c. Helps body absorb calcium into blood.

Major Functions4. Regulation of body temperature5. Ridding the body of wastes

Injuries and Repair1. Bruises

a. Tiny blood vessels below the skin burst.b. Color goes away after pigments breakdown

and reenter the blood stream.

Injuries and Repair2. Cuts

a. Any tear in the skin.b. Blood flows until a clot forms and then a scab

forms.c. Skin cells divide and grow under scab until

healed.

WARNING:

Behind this boxIs a really

gross picture.

Injuries and Repair3. Skin Grafts

a. Pieces of skin are cut from one part of a person’s body and moved to the injured or burned area where there is no skin.

b. Must be from own body or identical twin.

SKIN GRAFT

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REINFORCEMENTSKIN VIDEO