The Integumentary System The skin is the body’s largest organ Each square inch of human skin consists of twenty feet of blood vessels.
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.
Functions of the Skin • Protection • Barrier Function • Resistance to wear and tear • Vitamin D Production • Protection from UV light • Sensations • Temperature regulation Red with embarrassment! White from fright!
Skin Facts: • SKIN AND ITS ACCESSORY ORGANS-THE HAIR, NAILS, AND A VARIETY OF GLANDS, MAKE UP THE INTEGUMENTARY SYSTEM. • The Skin is the human body's Largest Organ. • The word INTEGUMENT comes from a LATIN word that means to COVER. • 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. • THE MOST IMPORTANT FUNCTION OF THE INTEGUMENTARY SYSTEM IS PROTECTION.
Skin Facts: • You have approximately 19,000,000 skin cells on every square inch of your body. • Humans shed about 600,000 particles of skin every hour – about 1.5 pounds a year. • House dust is mainly skin flakes! • Skin weighs about 2.5 kilograms - the largest organ in the body.
Skin Facts: • What hurts if you pull it, but doesn't hurt if you cut it? Your hair, of course! • Skin is elastic - it springs back into shape when stretched. Some medicines (estrogen, nicotine) can pass through the skin, but others cannot (insulin). This is because only fat-soluble substances can enter the skin, not water-soluble ones. • Skin grows faster than any other organ and continues to grow throughout our lives.
It’s the Skin We’re In! • (The epidermis is the topmost layer. It helps to prevent evaporation of water from the body and to protect the internal layers from harm. • The dermis is the middle layer. It contains the blood vessels, nerves, hair roots, and sweat glands. • The subcutaneous tissue is the deepest layer. It contains fats and connective tissue along with large blood vessels and nerves. Why do fingers and toes wrinkle in the bathtub?
EPIDERMIS • 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. • 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. • THERE ARE NO BLOOD VESSELS IN THE EPIDERMIS, WHICH IS WHY A SMALL SCRATCH WILL NOT CAUSE BLEEDING.
Keratin • KERATIN IS A TOUGH FIBROUS PROTEIN AND FORMS THE BASIC STRUCTURE OF HAIR, NAILS, AND CALLUSES. • In animals keratin forms cow horns, reptile scales, bird feathers, and porcupine quills. • 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. • THIS OUTER LAYER OF DEAD CELLS IS SHED OR WASHED AWAY ONCE EVERY 14 TO 28 DAYS.
Melanocytes • The Epidermis contains MELANOCYTES, CELLS THAT PRODUCE MELANIN, A DARK BROWN PIGMENT. • 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. • 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).
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.
Skin Cancers • Basal Cell Carcinoma • least malignant and most common • affects cells of the stratum basale • full cure in 99% of cases when removed surgically
Skin Cancers • Squamous Cell Carcinoma • Arises from the cells of the stratum spinosum • grows rapidly and metastisizes to adjacent lymph nodes if not removed. • chance of complete cure good with early detection
Skin Cancers • Malignant Melanoma • accounts for only 5% of skin cancers • often deadly • chance for survival about 50% • therapy includes wide surgical excision with immunotherapy.
ABCD Rule • (A) Assymmetry: the two sides of the pigmented spot or mole do not match. • (B) Border irregularity: the borders of the lesion are not smooth but exhibit indetations. • (C) Color: the pigmented spot contains areas of different colors (blacks, browns, tans, and sometimes blues and reds). • (D) Diameter: the spot is larger than 6 mm in diamter (the size of a pencil eraser).
Dermis • THE DERMIS IS 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. • 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. • The Dermis helps us to control our body temperature: • On a cold day when the body needs to conserve heat, the Blood Vessels in the Dermis NARROW. • On hot days, the Blood Vessels WIDEN, warming the skin and increasing heat loss.
Layers of the Dermis: Papillary Layer • Papillary layer • Areolar connective tissue with collagen and elastic fibers • Its superior surface contains peglike projections called dermal papillae • Dermal papillae contain capillary loops, Meissner’s corpuscles, and free nerve endings
Layers of the Dermis: Reticular Layer • Reticular layer • Accounts for approximately 80% of the thickness of the skin • Collagen fibers in this layer add strength and resiliency to the skin • Elastin fibers provide stretch-recoil properties
Blisters & Calluses • 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. • If the skin is subjected to pressure, the rate of mitosis will increase and create a thicker Epidermis; we call this a CALLUS.
Hypodermis • 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.
Epidermal Ridges (Fingerprints) • A friction ridge is a raised portion of the epidermis on the fingers and toes (digits), the palm of the hand or the sole of the foot, consisting of one or more connected ridge units of friction ridge skin. These are sometimes known as "epidermal ridges" which are caused by the underlying interface between the dermal papillae of the dermis and the interpapillary pegs of the epidermis. • These epidermal ridges serve to amplify vibrations triggered, for example, when fingertips brush across an uneven surface, better transmitting the signals to sensory nerves involved in fine texture perception. These ridges also assist in gripping rough surfaces, as well as smooth wet surfaces. • A fingerprint in its narrow sense is an impression left by the friction ridges of a human finger. In a wider use of the term, fingerprints are the traces of an impression from the friction ridges of any part of a human hand. A print from the foot can also leave an impression of friction ridges.
Fingerprints • Impressions of fingerprints may be left behind on a surface by the natural secretions of sweat from the eccrine glands that are present in friction ridge skin, or they may be made by ink or other substances transferred from the peaks of friction ridges on the skin to a relatively smooth surface such as a fingerprint card.
Arch Loop Whorl 3 Basic Types of Fingerprints
Red, Yellow, Black or White • The red and yellow hues of skin are due to hemoglobin in the red blood vessels, which pass through the capillaries beneath the epidermis, and carotene (yellowish pigment), which accumulates in fat cells found in the dermis and hypodermis. • Brown skin color is due to melanin.
Skin Color • Three pigments contribute to skin color: • 1. the amount and kind of melanin in the epidermis • 2. the amount of carotene deposited in the stratum corneum and subcutaneous tissue. • 3. the amount of oxygen bound to hemoglobin in the dermal blood vessels.
Malfunctioning Melanocytes • Albinism – melanocytes completely fail to secrete melanin. Hair, skin and/or iris are white. • Vitiligo – loss of pigment in certain areas of the skin producing white patches. • Freckles and Moles are formed when melanin becomes concentrated in local areas. What can cause a baby to turn orange?
Skin Color • Skin color is also influenced by emotional stimuli and can signal disease. • Erythema (redness) – embrassment, fever, hypertension, inflammation or allergy. • Pallor (pale) – fear, anger, low blood pressure, impaired blood flow. • Jaundice (yellow cast) – liver disorder • Bruises (black & blue) – blood has escaped from circulation and clotted. • Cyanosis (blue) – poorly oxygenated blood
Tattoos • Tattoos are made by inserting pigment into the skin with an electrically powered solid needle that punctures the skin between 50 and 3,000 times per minute. The needle penetrates the skin by about a millimeter and deposits a drop of insoluble ink into the skin with each puncture.
Tattoos • When you look at a person's tattoo, you're seeing the ink through the epidermis. The ink resides in the dermis. Dermis cells are far more stable than the cells of the epidermis, so the tattoo's ink will stay in place, with only minor fading and dispersion, for a person's entire life!
Tattoo Removal • Laser removal surgery is the most common form of tattoo removal. Lasers penetrate the skin and break up ink trapped in the dermis, fading or erasing the tattoo.
Tattoo Removal • Other methods of tattoo removal include: • Intense Pulsed Light Therapy • Excision • Dermabrasion
Appendages of the Skin • The Dermis contains TWO major types of CUTANEOUS GLANDS: SWEAT GLANDS AND SEBACEOUS, OR OIL GLANDS. • These Exocrine Glands PASS through the Epidermis and RELEASE THEIR PRODUCTS AT THE SURFACE OF THE SKIN.
Appendages of the Skin • 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. • 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. • Sebum is mildly toxic to some Bacteria - protection. • If the Ducts of Oil Glands become clogged with excessive amounts of Sebum, Dead Cells, and Bacteria, the Skin disorder ACNE can result.
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.
Don’t Sweat It! • Eccrine glands are the most common sweat gland . They produce sweat, a watery mixture of salts, antibodies and metabolic wastes. How much do we sweat in a day?
Hair • HAIR IS PRODUCED BY CELLS AT THE BASE OF STRUCTURES CALLED HAIR FOLLICLES. (Figure 46-15) • Hair Follicles are tubelike pockets of Epidermal Cells that extend into the Dermis. • Individual hairs are actually large columns of DEAD Cells that have filled with KERATIN.. • 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. • Hair Follicles are in close contact with Sebaceous Glands. The oily secretions of these Glands help maintain the condition of each individual hair.
Hair protects and insulates the body. • Hairs are found all over the body surface except the palms of the hands, soles of the feet, nipples, and lips. • Humans are born with as many hair follicles as they will ever have, and hairs are among the fastest growing tissues in the body. • Most individual hairs grow for several years and then fall out.
Hair Color • Hair pigment is made by melanocytes in the hair bulb, and varying amounts of different types of melanin (yellow, rust, brown, black) combine to produce all varieties of hair color from pale blond to pitch black.
It’s a Hairy Situation! • Melanocytes become less active with age. Gray hair is a mixture of pigmented and non-pigmented hairs. • Red hair results from a modified type of melanin that contains iron. Why do men have to shave everyday?