Download The skinny on Skin - Southington Public Schools

The Skinny on Skin
Integumentary—means “covering”. Skin is considered the
integumentary system. It is the largest organ in the body.
2 layers
Epidermis—the outermost layer. Top part is about 20-30 layers
of dead skin cells, protecting a bottom part containing living
cells. Epidermis includes the pigment melanin that protects
from sun and forms fingerprints. Replaced every 4 weeks.
Dermis—inner, thicker layer of skin. Contains blood vessels,
nerves, hair follicles, sweat glands, and oil glands.
Skin function
1. Protection—from germs and drying out.
2. Regulate body temperature—When body is hot, more blood
flows to dermis, releasing heat. When body is cold, blood is
kept away from dermis. Sweat evaporating also removes
excess heat.
3. Touch receptors—Heat, pain and pressure are felt.
4. Vitamin production—when exposed to sunlight, skin
produces some vitamin D.
Healing skin
Scrapes: only epidermis is damaged.
Cuts: dermis is damaged and bleeding occurs.
Repair process
A. Blood clots, forming a scab.
B. Dermal cells multiply rapidly and fill in gap. When
enough new skin is formed, scab falls off. Large cuts are
also repaired with connective tissue fibers. Fibers remain
and form scars.