1. Integumentary Notes
January 7th, 2015

2. Major Organ: Skin (largest organ in the body)
Functions:
Protects the body from injury and infection
Prevents the loss of water (dehydration)
Regulates body temperature
Gathers information about the environment
Produces vitamin D
Eliminates wastes (excretion)

3. Skin Diagram

4. Skin Structure: Epidermis
Epidermis: top layer of skin composed of epithelial tissue (no nerves or blood vessels)
Uppermost cells of the epidermis are dead and filled with keratin (protein in fingernails) which protects the lower layers
Epidermal cells only live for about 4 weeks
Pores: holes in the epidermis that lead to sweat glands

5. Skin Structure: Epidermis
Lower cells in the epidermis produce the pigment melanin (pigment = color molecule)
Melanin: dark pigment that protects skin cells from UV radiation in sunlight which can cause skin cancer
More melanin = darker skin
Less melanin = lighter skin

6. Skin Structure: Dermis
Dermis: Lower layer of skin with blood vessels and nerves (connective tissue); location of the following:
Sweat glands: release salt water from the body which evaporates on the surface of the skin, cooling the body; also excretes (releases) waste chemicals
Oil glands: found near hair follicles the oil waterproofs the hair and moistens the skin

7. Skin Structure: Dermis
Hair follicle: structure from which hair grows
Hair: sense insects, keeps body warm (not humans), top part is made of dead cells
Some cells in the dermis also produce Vitamin D when sunlight hits them
Vitamin D: regulates calcium uptake in the body, leads to strong bones