THE INTEGUMENTARY SYSTEM THE SKIN, HAIR, AND NAILS

DESCRIPTION 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.

the Skin is the human body's Largest Organ. the word INTEGUMENT comes from a LATIN word that means to COVER. THE MOST IMPORTANT FUNCTION OF THE INTEGUMENTARY SYSTEM IS PROTECTION.

THE SKIN’S 5 MAIN FUNCTIONS 1. SERVING AS A BARRIER AGAINST INFECTION AND INJURY. 2. HELPING TO REGULATE BODY TEMPERATURE. 3. REMOVING WASTE PRODUCTS FROM THE BODY. 4. PROVIDING PROTECTION AGAINST ULTRAVIOLET RADIATION FROM THE SUN. 5. PRODUCING VITAMIN D.

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.

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THE SKIN IS COMPOSED OF TWO MAIN LAYERS THE EPIDERMIS AND DERMIS.

THE OUTER MOST LAYER OF SKIN ITS LAYERS ARE MADE OF MOSTLY DEAD CELLS. MOST OF THE CELLS OF THE EPIDERMIS UNDERGO RAPID CELL DIVISION (MITOSIS). 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 KERATIN IS A TOUGH FIBROUS PROTEIN AND FORMS THE BASIC STRUCTURE OF HAIR, NAILS, AND CALLUSES OUR THICKEST EPIDERMIS IN ON THE PALMS AND SOLES THIS OUTER LAYER OF DEAD CELLS IS SHED OR WASHED AWAY ONCE EVERY 14 TO 28 DAYS THE EPIDERMIS CONTAINS MELANOCYTES, CELLS THAT PRODUCE MELANIN, A DARK BROWN PIGMENT. THERE ARE NO BLOOD VESSELS IN THE EPIDERMIS, WHICH IS WHY A SMALL SCRATCH WILL NOT CAUSE BLEEDING EPIDERMIS

DERMIS THE INNERMOST THICK LAYER OF THE SKIN COMPOSED OF LIVING CELLS. THE DERMIS LIES BENEATH THE EPIDERMIS AND CONTAINS BLOOD VESSELS, NERVE ENDINGS, GLANDS, SENSE ORGANS, SMOOTH MUSCLES, AND HAIR FOLLICLES. 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 (VASOCONSTRICTION) B. ON HOT DAYS, THE BLOOD VESSELS WIDEN (VASODIALATION), WARMING THE SKIN AND INCREASING HEAT LOSS. 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. 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.

. THE DERMIS CONTAINS TWO MAJOR TYPES OF GLANDS: SWEAT GLANDS AND SEBACEOUS, OR OIL GLANDS.

SWEAT GLANDS PRODUCE THE WATERY SECRETIONS KNOWN AS SWEAT, WHICH CONTAINS SALT, 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. They help to cool the body. 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. the production of Sebum is controlled by Hormones.

HAIR AND NAILS HAIR IS PRODUCED BY CELLS AT THE BASE OF STRUCTURES CALLED HAIR FOLLICLES. HAIR FOLLICLES ARE TUBE LIKE POCKETS OF EPIDERMAL CELLS THAT EXTEND INTO THE DERMIS. INDIVIDUAL HAIRS ARE ACTUALLY LARGE COLUMNS OF DEAD CELLS THAT HAVE FILLED WITH KERATIN.. NAILS GROW FROM AND AREA OF RAPIDLY DIVIDING CELLS KNOWN AS THE NAIL MATRIX OR NAIL ROOT. 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. NAILS REST ON A BED OF TISSUE FILLED WITH BLOOD VESSELS, GIVING THE NAILS A PINKISH COLOR. NAILS GROW AT A RATE OF 0.5 TO 1.2 MM PER DAY, WITH FINGERNAILS GROWING FASTER THAN TOENAILS.

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