The Integumentary System 36-3

1. BIO 1004 Flora The Integumentary System36-3

2. Serves as a barrier against infection and injury, helps regulate body temperature, removes waste products, and provides protection from UV rays Integumentary System

3. Single largest organ of the body Part of the integumentary system – “covering” of the body Includes hair, nails, and glands Contains several sensory receptors Skin

4. Made of 2 layers • Epidermis • Dermis • Below the dermis is the hypodermis which is a layer of fat and connective tissue • Helps insulate the body Skin Cont.

5. Outer layer of the skin • Has two layers • Outer layer – made of dead cells • Inner layer – made of living cells • Organelles get broken down as cell move towards the surface • Cells produce keratin and eventually die leaving a tough/flexible/waterproof covering • This outer layer replaces itself once every 4-5 weeks Epidermis

6. Epidermis also produces melanin, a brown pigment, that helps absorb UV rays Skin color is due to different amounts of melanin in the epidermis Has no blood vessels Epidermis Cont.

7. Inner layer of skin • Contains nerves, blood vessels, hair follicles, and glands • This region interacts with body systems to maintain homeostasis • Ex: blood vessel constriction • Contains 2 types of glands • Sweat – helps cool body and also gets rid of waste • Sebaceous – secrete sebum which helps make the skin flexible and waterproof Dermis

8. Hair and nails are made of keratin • Also forms bull horns, bird feathers, reptile scales, and porcupine quills in other animals • Hair on scalp functions in UV blocker and insulates • Hair in nostrils and ears prevent dirt from entering body • Hair is produced by hair follicles and nails are produced by nail roots • Both hair and nails fill with keratin and then die • Fun fact – fingernails grow 4X faster than toe nails Hair and Nails