1. BIO 1004 Flora

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

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

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

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

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

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

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