The Integumentary

System

Living things have their own “fences” and none is as important as the skin –

the boundary that separates the human body from the outside world.

“SKIN” - the single largest organ in the body

Integumentary (ihn-tehg-yoo-MEHN-ter-ee)System

What does the word integument means?

-it comes from a Latin word that means to cover, reflecting the fact that the skin and its accessory structures form a covering

over the entire body.

What make up the Integumentary

System?

The skin and its accessory organs --- the hair, nails and a

variety of glands.

What is the most important function of the Integumentary System?

-PROTECTION

It performs this function by acting as a barrier against infection and injury; helping

to regulate body temperature; removing waste products from the body; and

providing protection against ultraviolet radiation form the sun.

Because the main component of the integumentary system, the skin, contains

several types of sensory receptors, it serves as the gateway through which

sensations such as pressure, heat, cold, and pain are transmitted to the nervous

system.

Epidermis

Epidermis is the outermost layer of the skin.

Most of the cells of the epidermis undergo rapid cell division (mitosis). As new cells are produced, they plush the older cells to the surface of the skin. Here are the older cells become flattened, lose their cellular contents. And begin making keratin.

What is keratin?

- a tough fibrous protein

In humans, it forms the basic structure of hair, nails, and calluses. In other animals, keratin is more versatile --- forming cow horns, reptile scales, bird feathers, and

porcupine quills.

Keratinocytes, the keratin-producing cells, die and form a tough, flexible waterproof covering on the surface of the skin. This

outer layer of dead cells is shed or washed away at a surprising rate – once over 14 to

28 days.

The epidermis also contains melanocytes, or cells that produce melanin, a dark pigment. Although light-skinned and

dark-skinned people have roughly the same number of melanocytes, the

difference in their skin color is caused by the amount of melanin the melanocytes

produce and distribute. There are no blood vessels in the epidermis, which explains

why a slight scratch will not cause bleeding.

Dermis

What is dermis?

It is the innermost layer of the skin. It lies beneath the epidermis and contains blood vessels, nerve endings, glands, sense organs, smooth muscles, and hair follicles.

How does our body adopt during hot

and cold day?

When the body needs to conserve heat on cold day, the blood vessels in the dermis narrow, helping to limit heat loss. On hot days, the blood vessels widen, warming the skin and increasing heat loss. Beneath the dermis is the hypodermis, a layer of fat and loose connective tissue that insulates the body.

What are the two major types of glands

contained in the dermis?

Sweat glands and Sebaceous or oil glands

These glands pass through the epidermis and release their products at the surface of the skin. Sweat glands produce the watery secretion known as sweat, which contains salts, water, and other compounds.

These secretions are stimulated by nerve impulses that cause the production of sweat when the temperature of the body is raised. Sebaceous glands produce an oily secretion known as sebum that spreads out along the surface of the skin and keeps the keratin-rich epidermis flexible and waterproof.

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HAIR AND NAILS…..