THE INTEGUMENTARY SYSTEM36-3

BIO 1004Flora

INTEGUMENTARY SYSTEM

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

SKIN

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 CONT.

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

EPIDERMIS

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 CONT.

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

DERMIS

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

HAIR AND NAILS

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