**Integumentary System**

Functions of the skin:

1. Barrier to unwanted microorganisms

2. Barrier to ultraviolet rays (melanin enables the skin to absorb harmful radiation from the sun)

3. Tempature regulation: rids excess heat by sweating and stimulates shivering to keep warm by tightening blood vessels

4. Water proof covering of the skin prevents substances from being absorbed into the body

5. Also fat is stored in the skin layers.


-main component of skin's surface
-tough fibrous protein
-can be found in hair
-provides protection & warmth
-can be found in nail to protect delicate ends of digits


Filters harmful materials
-causes the skin to darken
Responsive Layer- In direct sunlight, the epidermis & dermis produce extra melanin
-Fair complexions have less melanin and are more susceptible to sunburn


is on every part of the body
-helps maintain body temperature
-eyelashes help filter out harmful particles
-grows from follicles that contain the lower shaft and root of the hair
-It grows through the dermis and epidermis, and is maintained from the sebaceous glands
-Melanin determines the hair color

-Goose pimples are formed when you are cold. The tiny muscles attached to the follicles tighten up and cause the hair to stand on end.


made of a tough protein called keratin

protects the end of our fingers and toes

grow at the rate of about .05 to 1.2 mm per week

healthy nails are pink which show a healthy supply of blood

grow from the nail matrix or nail root

without them we couldn't: itch, scratch or untie a knot