Warm-up: 25 January 2012

• ____________ helps maintain healthy bones by making bones grow stronger and denser.• 140) heredity – the passing of traits from

parents to offspring• 141) hibernation – to pass the winter in a

sleeping or resting state• 142) inherit – to receive by genetic

transmission; to have handed on to one by someone else

Exercise

Daily Objective

• Describe and identify the structure and function of the integumentary system.

The Integumentary System

Chapter 5

The Integumentary System

• The skin is the largest organ in the human body. • If an adult’s skin were stretched out flat,

it would cover an area larger than 1.5 square meters—about the size of a mattress on a twin bed.

The Integumentary System

• Composed of the skin, sweat and oil glands, hair, and nails.• Accounts for 7% of the body’s weight.•Major role is protection from pathogens

and dehydration.• Varies in thickness from 1.5 to 4.0 mm.• Composed of 3 distinct layers.• Epidermis, Dermis, and Hypodermis or

superficial fascia

The Integumentary System

• Role of the Integumentary System• covers the body• prevents the loss of water• protects the body from injury and

infection• helps to regulate body temperature• eliminate wastes• gather information about the environment• produce vitamin D

The Integumentary System

• Covers the Body & Prevents Water Loss• Like plastic wrap that keeps food from

drying out, the skin prevents the loss of important fluids such as water.

The Integumentary System

• Protects the Body from Injury and Infection• Skin protects the body by forming a

barrier that keeps disease-causing microorganisms and harmful substances outside the body.

The Integumentary System

• Helps to Regulate Body Temperature• The skin helps the body maintain

homeostasis, or stable internal conditions, by keeping body temperature steady in spite of changing external conditions.•When you become too warm, blood

vessels enlarge to increase the amount of blood that flows through them allowing heat to move from your body into the outside environment.

The Integumentary System

• Eliminates Waste• Sweat glands respond to excess heat by

producing perspiration. • Perspiration evaporates from your skin,

heat moves into the air. • Perspiration contains some dissolved

waste materials.

The Integumentary System

• Gathers Information About Environment• The nerves in skin provide information

about such things as pressure, pain, and temperature. • Pain messages are important because they

warn you that something in your surroundings may have injured you.

The Integumentary System

• Produces Vitamin D • Produces vitamin D in the presence of

sunlight. • Vitamin D is important for healthy bones

because Vitamin D helps the cells in your digestive system to absorb the calcium in your food. • Your skin cells need only a few minutes of

sunlight to produce all the vitamin D you need in a day.

Epidermal Cell Life Cycle• Each epidermal cell begins life deep in the

epidermis, where cells divide to form new cells. • The new cells gradually mature and move

upward in the epidermis as new cells form beneath them. • After about two weeks, the cells die and become

part of the surface layer of the epidermis. • Cells remain in this layer for about two weeks. • Then they are shed and replaced by the dead

cells below.

Epidermis

• Outermost layer.• Protects the dermis• Contains 4 distinct cell types and 4 to 5

distinct layers.• When cells fall away, they carry with them

bacteria and other substances that settle on the skin. • Every time you rub your hands together, you

lose hundreds, even thousands, of dead skin cells.

Epidermis

•melanin - a pigment, or colored substance, that gives skin its color• Located at the deepest layer of the

epidermis.• If you have melanin that builds up in one

place, it will result in freckles.•Moles occur when cells in the skin grow in

a cluster instead of being spread throughout the skin.

The Dermis

• Lower layer of the skin•Made mostly of connective tissue.• The hide of the human body.• Contains the hair follicles, sweat glands, oil

glands, lymphatic vessels, and many sensory receptors.

The Dermis – Sweat Glands• Sweat glands produce perspiration, which

reaches the surface through openings called pores.• Sweat Glands—more than 2.5 million per

person.• Sweat contains chemicals, odorants, and a

small amount urea.• Sweat itself is not the cause of body odor,

but rather the bacteria on the skin which feed on the sweat.• Empty into hair follicles. Begin to function at

puberty.

The Dermis - Hair

• Strands of hair grow within the dermis in structures called follicles.• The hair that you see above the skin’s

surface is made up of dead cells.• Oil produced in glands around the hair

follicles waterproofs the hair. In addition, oil that reaches the surface helps to keep the skin moist. • Covers the entire body except for the

palms, soles, and lips•Mostly dead keratinized cells.

The Dermis - Hair

Nails

Nails

Caring for Your Skin

• Eating Properly • Your skin is always active. Activities

require energy—and a well-balanced diet provides the energy

• Drinking Water •When you participate in strenuous

activities you can perspire up to 10 liters of liquid a day.

Caring for Your Skin

• Limiting Sun Exposure • You can take actions to protect your skin

from cancer and early aging. • Cancer is a disease in which some cells

divide uncontrollably. (Basal cell carcinoma & Squamous Cell, & Melanoma)• Aging effects - thinning of the skin and

slowing of epidermal cell replacement.

Caring for Your Skin

• Keeping Skin Clean • mild soap helps you get rid of dirt and harmful

bacteria• oil glands are more active in teenage years• acne - when oil glands become clogged with oil

and bacterial infection occurs• fungi can also live on and infect the skin,

growing best in warm, moist surroundings (i.e. - athlete’s foot)

Burns

• Denaturation of cell proteins.• Dehydration, protein loss, and infection.• First degree burns—only the epidermis.• Second degree burns—epidermis and upper

dermis. May include blisters.• Third degree burns—full thickness. Not painful.

Skin grafting is almost always necessary.• Grafting techniques• Autograft• Dangers of facial burns and burns near joints.