The Integumentary System

1. The Integumentary System The skin, nails, hair and glands

2. Different functions • Serves as a barrier against infection and injury • Helps regulate body temperature • Removes waste products from the body • Provides protection against UV radiation • Serves as a gateway of sensation • Pressure, heat, cold, pain

3. Different layers of skin • 1. epidermis • 2. dermis • 3. hypodermis

4. Epidermis • The outer layer of skin • 2 layers • Outer epidermis • Part that comes into contact with the environment • Made up of dead cells • Inner epidermis • Made up of living cells • Undergo rapid cell division, pushing older cells to surface • Cells produce keratin (a special protein) to make skin tough and waterproof

5. Epidermis • The outer layer of dead cells is shed at a rate of once every 4-5 weeks

6. Epidermis • Contains melanocytes • Melanocytes are cells that produce melanin, which is a dark brown pigment • Melanin helps protect the skin from UV light • The amount of melanin produced by the melanocytes is responsible for the variety of skin colors

7. Dermis • The Inner layer of the skin • Lies beneath the epidermis and contains collagen fibers, blood vessels, nerve endings, glands, sensory receptors, smooth muscle and hair follicles

8. How does the skin regulate body temperature? • When the body is cold, blood vessels in the dermis become narrow • This prevents heat from the core from being lost to the environment (skin is the barrier between body and environment) • When the body is hot, the blood vessels widen • This brings more heat from the body core which is given off to the environment

9. Glands of the Dermis • Sweat Glands • When the body is hot, these glands produce sweat • Sweat evaporates and increases heat loss from the body • Sweat is mostly made up of water and salt • It can also contain other substances that the body wants to get rid of • In this way the skin acts in an excretory roll as well

10. Glands of the Dermis • Sebaceous (Oil) Glands • Produce an oily secretion call sebum • Sebum spreads along the skin to help keep the epidermis flexible and waterproof

11. Sun exposure and skin • Benefits • Body relies on sunlight to help make vitamin D • Negatives • Exposure in excess and lead to skin cancer • Always wear sunscreen for prevention

12. Hair and Nails • The basic component of human hair and nails is keratin • In other animals keratin also makes up horns in cows, quills on porcupines, feathers on birds, scales on reptiles

13. Hair • Hair protects our scalp from UV light, prevents particles from entering our body through the nose, eye and ear, and provides insulation from the cold • Hair follicles • Tube like pockets of epidermal cells where hair is produced • Have an oil gland that secretes oil to protect the hair as well

14. Nails • Grow from an area of rapidly dividing cells known as the nail root • Cells being produced at the nail root fill with keratin and produce the tough platelike structure of nails • Interesting fact: • Fingernails grow 4x faster than toenails

15. Hair

16. Hypodermis • Is a subcutaneous layer of fat and connective tissue beneath the dermis that help to insulate the body • Primary site of fat storage in the body