The Integumentary System

The Integumentary System

What Covers You

Integumentary SystemThe Integumentary System includes all the

external coverings of the body including the skin, nails and hair.

The skin is the largest organ in your body.

Functions of the SkinSkin covers your bones and muscles and

protects them from the external environment.

It protects the cells and tissues under the skin from damage.

Skin is the first line of defense against dirt, bacteria, viruses, and other substances that might enter the body.

Functions of the Skin (cont.)Sensory receptors are special cells in your

skin that detect texture and temperature and sense pain.

The more sensory receptors there are in an area of skin, the more sensitive it is.

Functions of the Skin (cont.)Skin helps control body temperature.Skin lowers your body temperature by

producing sweat, which evaporates and allows excess thermal energy to leave the body.

Skin also lowers body temperature by releasing thermal energy from blood vessels.

If your skin is exposed to sunlight, it can make vitamin D which helps it absorb calcium and phosphorous to promote bone growth.

Functions of the Skin (cont.)The skin helps to eliminate waste

products produced by normal cellular processes.

Water, salts, and other waste products are removed through the pores.

Structures of the Skin: EpidermisThe epidermis is the outermost layer of skin

and the only layer in direct contact with the outside environment.

Cells of the epidermis are constantly shed and replaced by new cells.

The epidermis produces melanin, which is a pigment that protects the body by absorbing some of the Sun’s damaging ultraviolet rays.

Structures of the Skin: DermisThe dermis is the thick layer of skin beneath the

epidermis that gives skin strength, nourishment, and flexibility.

The dermis contains sweat glands, blood vessels, nerves, hair follicles, and muscles.

Structures of the Skin: Fatty LayerThe fatty layer is the innermost layer of skin

which insulates the body, acts as protective padding, and stores energy.

Skin Injuries: BruisesA bruise is an injury where blood vessels in

the skin are broken, but the skin is not cut or opened.

The broken blood vessels release blood into the surrounding tissue.

Skin Injuries: CutsWhen you break one or more layers of skin, it is

called a cut.The released blood of a cut will usually thicken and

form a scab over the cut which prevents dirt and other outside substances from entering the body.

Skin heals by producing new skin cells that eventually repair the cut.

Skin Injuries: BurnsA burn is an injury to skin caused by contact

with hot objects, extremely cold objects, chemicals, radiation, electricity, or friction.

Burns are classified by the depth of damage to the skin as first-degree, second-degree, or third-degree burns.

Degrees of Burns: First

Degree of Burns: Second

Degree of Burns: Third

Healthy SkinProtecting skin from the ultraviolet rays in

sunlight and eating a balanced diet are two ways to help keep skin healthy.

The Skin and HomeostasisSkin can make vitamin D and protect the

body from outside substances, which helps regulate the body’s internal environment.

Skin and the circulatory system help cool the body when it becomes overheated.

If the body becomes cold, blood vessels constrict and reduce thermal energy loss.

System Working TogetherThe skin, the nervous system, and the

muscular system work together to maintain homeostasis.

Hair & Nails• A hair forms at the bottom of a tiny sac called

a hair follicle. Hair helps protect skin from ultraviolet light and helps regulate body temperature in most mammals.

• A nail grows from living cells in the nail root at the base of the nail. Nails protect the tips of your fingers and toes.

Lesson Review Questions: 1What is the name of the pigment that protects the body by absorbing some of the Sun’s ultraviolet rays?

A. SweatB. Vitamin DC. MelaninD. Skin

Lesson Review Questions: 2A bruise is the result of breaking which of these?

A. EpidermisB. Blood VesselC. DermisD. Scab

Lesson Review Questions: 3What is the name of the thick layer of skin beneath the epidermis that gives skin strength, nourishment, and flexibility?

A. MelaninB. Fatty LayerC. Integumentary SystemD. Dermis