Download INTEGUMENTARY SYSTEM

Anatomy and Physiology Lecture Notes
Supplementary Unit – The Integumentary System
INTEGUMENTARY SYSTEM
The integumentary system, consisting of the skin, hair and nails, act as a barrier to protect the
body from the outside world. It also functions to retain body fluids, protect against disease,
eliminate waste products, and regulate body temperature.
OBJECTIVES: Identify the structures that make up the integumentary system. Describe the
functions of the skin. Distinguish between the two layers that form the skin. Compare the
structure of hair with that of nails. Identify two types of glands found in the skin, and describe
their function.
1. SKIN AND ITS ACCESSORY ORGANS-THE HAIR, NAILS, AND A VARIETY OF
GLANDS, MAKE UP THE INTEGUMENTARY SYSTEM.
2. The Skin is the human body's Largest Organs.
3. The word INTEGUMENT comes from a LATIN word that means to COVER.
4. THE MOST IMPORTANT FUNCTION OF THE INTEGUMENTARY SYSTEM IS
PROTECTION.
5. IT PERFORMS THIS FUNCTION BY: (The FIVE Main Functions of the Integumentary
System)
A. SERVING AS A BARRIER AGAINST INFECTION AND INJURY.
B. HELPING TO REGULATE BODY TEMPERATURE.
C. REMOVING WASTE PRODUCTS FROM THE BODY.
D. PROVIDING PROTECTION AGAINST ULTRAVIOLET RADIATION FROM
THE SUN.
E. PRODUCING VITAMIN D.
6. Because 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.
7. The Skin is composed of Two Main Layers - The EPIDERMIS and DERMIS.
EPIDERMIS
1. The OUTER most layer of Skin is known as the
EPIDERMIS. It is composed of many sheets of Flattened,
Scaly Epithelial Cells. This is a thin outer layer of skin.
2. Its layers are made of Mostly DEAD CELLS.
3. Most of the cells of the Epidermis undergo rapid cell division (MITOSIS).
4. As new cells are produced, they push Older cells to the surface of the skin. The older cells
become Flattened, Lose their Cellular Contents and begin making KERATIN.
5. KERATIN IS A TOUGH FIBROUS PROTEIN AND FORMS THE BASIC STRUCTURE
OF HAIR, NAILS, AND CALLUSES.
6. In animals keratin forms cow horns, reptile scales, bird feathers, and porcupine quills.
7. Eventually, the Keratin-producing Cells (KERATINCYTES) DIE AND FORM A TOUGH,
FLEXIBLE WATERPROOF COVERING ON THE SURFACE OF THE SKIN. Our thickest
Epidermis in on the palms and soles.
8. THIS OUTER LAYER OF DEAD CELLS IS SHED OR WASHED AWAY ONCE EVERY
14 TO 28 DAYS.
9. The Epidermis contains MELANOCYTES, CELLS THAT PRODUCE MELANIN, A
DARK BROWN PIGMENT.
10. BOTH LIGHT SKINNED AND DARK SKINNED PEOPLE HAVE ROUGHLY THE
SAME NUMBER OF MELANOCYTES, THE DIFFERENCE IN OUR SKIN COLOR IS
CAUSED BY THE AMOUNT OF MELANIN THE MELANOCYTES PRODUCE AND
DISTRIBUTE.
11. The Amount of Melanin produced in Skin depends on TWO Factors - Heredity and the
Length of Time the Skin is Exposed to Ultraviolet Radiation (Tanning).
12. Melanin is important for protection, by absorption of Ultraviolet Radiation from the sun. All
people, but especially people with Light Skin, need to minimize exposure to the sun and protect
themselves from its Ultraviolet Radiation, which can Damage DNA in Skin Cells and lead to
deadly forms of Skin Cancer such as MELANOMA CANCER.
13. THERE ARE NO BLOOD VESSELS IN THE EPIDERMIS, WHICH IS WHY A SMALL
SCRATCH WILL NOT CAUSE BLEEDING.
DERMIS
1. THE DERMIS IS THE INNERMOST THICK LAYER OF THE SKIN COMPOSED OF
LIVING CELLS.
2. The Dermis lies beneath the Epidermis and contains BLOOD VESSELS, NERVE ENDINGS,
GLANDS, SENSE ORGANS, SMOOTH MUSCLES, AND HAIR FOLLICLES.
3. The Dermis helps us to control our body temperature:
A. On a cold day when the body needs to conserve heat, the Blood Vessels in the Dermis
NARROW.
B. On hot days, the Blood Vessels WIDEN, warming the skin and increasing heat loss.
4. Tiny Muscle fibers attach to Hair Follicles contract and pull hair upright when you are cold or
afraid, producing what is commonly called Goose Bumps.
5. Beneath the Dermis is the HYPODERMIS, (SUBCUTANEOUS LAYER), A LAYER OF
FAT AND LOOSE CONNECTIVE TISSUE THAT INSULATES THE BODY AND ACTS AS
AN ENERGY RESERVE.
6. The Dermis contains TWO major types of GLANDS: SWEAT GLANDS AND
SEBACEOUS, OR OIL GLANDS.
7. These Glands PASS through the Epidermis and RELEASE THEIR PRODUCTS AT THE
SURFACE OF THE SKIN.
8. SWEAT GLANDS PRODUCE THE WATERY SECRETIONS KNOWN AS SWEAT,
WHICH CONTAINS SALT, WATER, AND OTHER COMPOUNDS.
9. These secretions are stimulated by nerve impulses that cause the production of sweat when the
temperature of the body is raised. They help to cool the body.
10. SEBACEOUS GLANDS, (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.
11. The production of Sebum is controlled by Hormones.
12. Oil Glands are usually connected by Tiny Ducts (Exocrine Glands) to Hair Follicles. Sebum
coats the surface of the skin and the shafts of hair, preventing excess water loss and lubricating
and softening the Skin and Hair.
13. Sebum is mildly toxic to some Bacteria - protection.
14. If the Ducts of Oil Glands become clogged with excessive amounts of Sebum, Dead Cells,
and Bacteria, the Skin disorder ACNE can result.
15. When first wearing new shoes, the skin of the foot may be subject to friction. This will
separate layers of Epidermis, or separate the Epidermis from the Dermis, and tissue fluid may
collect, causing a BLISTER.
16. If the skin is subjected to pressure, the rate of mitosis will increase and create a thicker
Epidermis; we call this a CALLUS.
BURNS
1. FLAMES, HOT WATER OR STEAM, SUNLIGHT, ELECTRICITY, OR CORROSIVE
CHEMICALS MAY CAUSE BURNS OF THE SKIN.
2. THE SEVERITY OF BURNS RANGES FROM MINOR TO FATAL AND THE
CLASSIFICATION OF BURNS IS BASED ON THE EXTENT OF DAMAGE.
3. FIRST-DEGREE BURN- ONLY THE SUPERFICIAL EPIDERMIS IS BURNED, AND IS
PAINFUL BUT NOT BLISTERED. Causes death of Epidermal Cells.
4. SECOND-DEGREE BURN- DEEPER LAYERS EPIDERMIS ARE EFFECTED, COULD
HAVE INFLAMMATION, BLISTERS, AND THE BURNED SKIN IS OFTEN PAINFUL.
5. THIRD DEGREE BURN- THE ENTIRE EPIDERMIS IS CHARRED OR BURNED
AWAY, AND THE BURN MAY EXTEND INTO THE DERMIS. OFTEN SUCH A BURN IS
NOT PAINFUL AT FIRST, IF THE RECEPTORS IN THE DERMIS HAVE BEEN
DESTROYED.
6. EXTENSIVE THIRD-DEGREE BURN- POTENTIAL LIFE-THREATENING BECAUSE
OF LOSS OF SKIN, WITHOUT THIS NATURAL BARRIER, LIVING TISSUE IS EXPOSED
TO THE ENVIRONMENT AND IS SUSCEPTIBLE TO INFECTION AND DEHYDRATION.
HAIR AND NAILS
1. HAIR IS PRODUCED BY CELLS AT THE
BASE OF STRUCTURES CALLED HAIR
FOLLICLES. (Figure 46-15)
2. Hair Follicles are tubelike pockets of
Epidermal Cells that extend into the Dermis.
3. Individual hairs are actually large columns of
DEAD Cells that have filled with KERATIN..
4. Rapid cell growth at the base of the Hair
Follicle in the HAIR ROOT causes hair to grow
longer. Hair gets its color from Melanin.
5. Hair Follicles are in close contact with
Sebaceous Glands. The oily secretions of these
Glands help maintain the condition of each
individual hair.
6. Hair protects and insulates the body.
7. Most individual hairs grow for several years
and then fall out.
8. NAILS GROW FROM AND AREA OF RAPIDLY DIVIDING CELLS KNOWN AS THE
NAIL MATRIX or NAIL ROOT. (Figure 46-16)
9. THE NAIL MATRIX IS LOCATED NEAR THE TIPS OF THE FINGERS AND TOES.
10. 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.
11. Nails rest on a Bed of tissue filled with Blood Vessels, giving the nails a Pinkish Color.
12. Nails grow at a rate of 0.5 to 1.2 mm per day, with fingernails growing faster than toenails.