Chapter 15, Section 4The Skin

Monday, February 15, 2010

Pages 494 -- 500

Objectives Describe the functions of skin. Identify and describe the layers of the

skin. List ways that individuals can keep skin

healthy.

Vocabulary Words Epidermis Melanin Dermis Pore Follicle Cancer Acne

Function of the Skin Covers the body and prevents the loss

of water. Protects the body from injury and

infection. Helps regulate body temperature,

eliminates wastes, gather information about the environment, and produce vitamin D

Skin as Protection Forms a barrier.

Disease-causing microorganisms and harmful substances are kept outside the body.

Keeps important substances inside the body.

Prevents loss of water.

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Regulating Temperature When you become too warm, the blood

vessels enlarge to increase the amount of blood flow. This allows heat to move from your body

into the outside environment. Sweat glands to respond to excess heat

by producing perspiration.

Skin Produces Vitamin D Vitamin D is important for healthy

bones. Vitamin D aids in the digestive system to

absorb calcium. Vitamin D is produced by some skin

cells in the presence of the sun. Only a few minutes in the sun each day is

needed.

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The Epidermis The epidermis is the

OUTERMOST layer of the skin.

It is thinner than the dermis.

It does not have nerves or blood vessels.

Openings on the surface are called pores.

Respiration/wastes exit through openings.

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Epidermis -- cont’d Cells have a definite life cycle.

Life begins deep in the epidermis. Cells move up towards the surface as new

cells mature and move upward in the epidermis.

Cells die and become part of the surface layer in about 2 weeks.

They then shed and are replaced by the dead cells below.

Dermis The dermis is the

lower layer of the skin.

Located below the epidermis and above a layer of fat. The fat layer acts as

padding for the internal organs and serves as insulation.

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The Dermis - Cont’d The dermis contains nerve and blood vessels. The dermis contains other structures such as

sweat glands, hairs, and oil glands. Strands of hair grow within the dermis in

structures called follicles. Oil is produced I glands around the hair

follicles.

Caring For Your Skin Four simple habits can help keep your

skin healthy: Eat properly Drink plenty of water Limit sun exposure Keep skin clean and dry

Homework Workbook 15.4 (2/17) Vocabulary quiz 15.4 (2/17)