Integumentary System Turn to your neighbor…what is the integumentary system?

Skin Nails Hair Act as a protective barrier to the outside world.

Body Bucket Retains:  body fluids  protect against disease  eliminate waste products  regulate body temperature Basically, holds all your “stuff” from falling out or getting contaminated.

Fun Facts Human body’s largest organ Integumentary derives from a Latin word meaning to cover Most important function…PROTECTION The outer layer of dead skin cells is shed or washed away once every 14 to 28 days

How skin protects… Serving as a barrier against infection and injury Helping to regulate body temperature: by radiation and evaporation. When you are sick, your temp goes up, the body delivers the internal temperature to the surface of your skin where it is taken away by evaporation. When your temp drops, the body signals that heat must be saved and sweating will stop. Removing waste products from the body Providing protection against ultraviolet radiation from the sun Producing vitamin D

Two main layers Epidermis Dermis

Sensory receptors Perceives sensations such as:  Pressure  Heat  Cold  Pain All of which are then transmitted to the nervous system.

Epidermis Outer most layer of skin Composed of many sheets of flattened, scaly epithelial cells Thin layer of skin made mostly of dead cells Undergoes rapid cell division New cell are produces pushing older cells to the surface of the skin.  The older skin begin making keratin There are no blood vessels in the epidermis, which is why a small scratch will not cause bleeding

Keratin Is a tough fibrous protein Forms basic structure for hair, nails and calluses Eventually, the keratin-producing cells die and form a tough, flexible waterproof covering on the surface of the skin

Melanin (a dark brown pigment) Skin pigment Both light skinned and dark skinned people have roughly the same number of melanocytes (cells that produce pigment) The difference in our skin color is caused by the amount of melanin the melanocytes produce and distribute.

Amount of Melanin Dependent on two factors  Heredity  Length of time skin is exposed to ultraviolet radiation Role – Absorption of ultraviolet radiation

Dermis Middle thick layer of the skin composed of living cells Contains: blood vessels, nerve endings, glands, sense organs, smooth muscles, and hair follicles Helps control body temperature

Body temperature Cold days the blood vessels narrow  Decreases surface area in order to conserve body heat Hot days the blood vessels widen  warming the skin and increasing heat loss

Goose Bumps Tiny muscle fibers attach to hair follicles contract and pull hair upright when you are cold or afraid producing what we call Goose Bumps

Dermis contains 2 major glands Sweat glands  Secretions are stimulated by nerve impulses that cause the production of sweat when the temperature of the body is raised.  2,000,000 pores in your skin are connected to sweat- glands.  They help cool the body off. Oil glands  Produce oily secretion known as sebum that spreads out along the surface of the skin and keeps the keratin rich epidermis flexible and waterproof.

Hypodermis This layer is beneath the dermis A layer of fat and loose connective tissue that insulates the body and acts as an energy reserve.

What causes blisters? The rubbing of the separate skin layers The Epidermis and the Dermis separate Tissue fluid may collect between the layers Calluses  Skin prone to this pressure will create an area of thicker epidermis causing a callus

Burns Severity ranges from minor to fatal First degree burns  Only the superficial epidermis are effected  Painful but no blistering  Causes death of epidermal cells Second degree burns  Deeper layers of the epidermis are charred  Inflammations, blisters and painful

…burns continued Third degree burns  The entire epidermis is charred or burned away, and the burn may extend into the dermis  Not usually painful at first if the receptors in the dermis have been destroyed Extensive third degree burns  Loss of skin  Potentially life threatening, because the natural barrier has been destroyed exposing tissue that is extremely susceptible to infection and dehydration.

Hair Produced by cells at the base of the structures called hair follicles Hair follicles – tube like pockets of epidermal cells that extend into the dermis Individual cells are actual large columns of dead cells that have been filled with keratin Hair gets color from melanin Protects and insulates the body

Nails Grows from rapidly divided cells known as the nail matrix or nail root Nail matrix is located near the tips of the fingers and toes During cell division, the cells fill with keratin and produce a tough, strong platelike nail that covers and protects the tips of the fingers and toes The pinkish color comes from the blood vessels in the nail bed Nails grow at a rate of 0.5 to 1.2 mm per day  Finger nails grow faster than toe nails

Diagram of the skin

Cleavage Lines These “lines” are really crease marks on the skin and the same for most bodies. Your “birthday suit” It is a suit with many surfaces: wet (mouth), dry, smooth, rough, pleats and folds, tracks and ridges (toes, fingers, for gripping). Spots will tend to thinken where usage is heaviest (feet, which can be 3/16 inch thick!) and thinnest (eyes 1/500” thick!)

Integumentary System Review What does Integumentary mean? What are the three layers of the skin? What is the purpose of this system? Why is it important?

Care of this system Why is it important to take care of this system? Talk to a partner. Decide what can be done to take care of this system.

Abuses/Diseases of this system What can happen if you do not take care of this system? Discuss with a partner