<<

What part of your body has to be partly dead to keep you alive? Here are some clues: It comes in many colors, it is the largest in the body, and it is showing right now!

Did you guess your ? If you did, you guessed correctly. Your skin, , and nails make up your integumentary system (in TEG yoo MEN tuhr ee SIS tuhm). The integumentary system covers your body and helps you maintain . Integumentary System - Skin Integumentary System - Skin The Body’s Tough Covering The skin covers and protects the body from , , and loss. It is the largest organ in our body. Our skin has five basic functions.

1. Protecting the Body 2. Maintaining 3. Eliminating Wastes 4. Gathering Information 5. Producing D Skin Protecting the Body The skin protects us by forming a protective barrier that keeps out disease-causing and harmful substances outside the body. It also keeps important substances in the body, i.e. water. It’s like plastic wrap that keeps food from drying out.

Barrier Purpose 1. Keep out disease causing microorganisms 2. Keep out harmful substances 3. Keep in water Skin Maintaining Temperature Skin maintains a steady temperature. Many vessels run throughout the skin. When the body gets too warm the blood vessels enlarge which increases blood flow and the amount of flow increases. This allows heat is given off and move from the body into the outside environment.

Sweat responds to excess heat in the body causes . It is a salty that flows to the surface. As it evaporates from the skin it cools the surface. Skin Eliminating Waste Perspiration consists of dissolved waste material from the breakdown of chemicals during cellular processes. When you perspire (sweat) the body eliminates waste. Examples of wastes eliminated are ammonia, , salts, and sugars. Below are beads of sweat on the skin with waste. Skin Eliminating and Waste Exchange The blood vessels in the skin expand and dilate which releases heat or holds heat in. As they expand, blood flow increases and heat is released to our skin which holds about 3 million sweat glands. Skin Gathering Information The skin also gathers information about the environment. To understand how the skin does this, place your fingertips on the skin of your arm and press down firmly. Then lightly pinch yourself. You have just tested some of the in your skin. The nerves in skin provide information about such things as , pain, and temperature. Pain messages are important because they warn you that something in your surroundings may have injured you. Skin Producing Lastly, some of the skin cells produce vitamin D in the presence of sunlight. Vitamin D is important for healthy because it helps the cells in your digestive system to absorb the in your food. Your skin cells need only a few minutes of sunlight to produce all the vitamin D you need in a day. Vitamin D is needed for the growth and development of the bones. Skin The The skin is organized into two main layers, the epidermis and the . The epidermis is the outer layer of the skin. In most places, the epidermis is thinner than the dermis. It is thicker on the palms and soles. The epidermis does not have nerves or blood vessels. This is why you usually don’t feel pain from very shallow scratches, and why shallow scratches do not bleed. A third innermost layer is . Skin The Epidermis Epidermis Structure Like all cells, the cells in the epidermis have a life cycle. Each epidermal begins life deep in the epidermis, where cells divide to form new cells. The new cells 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 epidermal surface layer. Under a microscope, this surface layer of dead cells resembles flat bags laid on top of one another. Cells remain in this layer for about two weeks. Then, they are shed and replaced by the dead cells below. Skin Epidermis Epidermis Function In some ways, the cells of the epidermis are more valuable dead than alive. Most of the protection provided by the skin is due to the layer of dead cells on the surface. The thick layer of dead cells on your fingertips, for example, protects and cushions your fingertips. Also, the shedding of dead cells carries away and other substances that settle on the skin. Every time you rub your together, you lose thousands of dead skin cells and any bacteria on them. Skin The Epidermis Some cells in the inner layer of the epidermis help to protect the body, too. On your fingers, for example, some cells produce hard fingernails, which protect the fingertips from injury and help you scratch and pick up objects. Also on your toes, some cells produce hard toenails, which protect the tips of the toes from injury. Skin The Epidermis Other cells deep in the epidermis produce , a , or colored substance, that gives skin its color and protects it. The more melanin in your skin, the darker the skin. If you have less melanin, you have lighter skin color. Exposure to sunlight stimulates the skin to make more melanin. This is why you tan when exposed to sunlight. People with lighter skin can absorb more Vitamin D from the sun, but people with darker skin are less likely to get skin . Melanin production helps to protect the skin from burning. Skin The Dermis The dermis is the inner layer of the skin. Notice that it is located below the epidermis and above a layer of fat. This fat layer pads the internal organs and helps keep heat in the body.

The dermis contains nerves and blood vessels. The dermis also contains sweat glands, , and oil glands. Sweat glands produce perspiration, which reaches the surface through openings called pores. They regulate body temperature, release waste through the process below: - when vessels dilate, pores on the skin open and perspiration is released from sweat glands. This allows your body to cool off. - cells use energy and and have waste which is released through sweat Skin The Dermis (Hair) Strands of hair grow within the dermis in structures called follicles (FAHL ih k ulz). The hair that you see above the skin’s surface is made up of dead cells. Older cells get pushed upward. The living cells are in the follicle. Oil produced in glands around the hair follicles help to waterproof the hair. In addition, oil that reaches the surface of the skin helps to keep the skin moist. Protects the skin from UV light, helps regulate the body temperature, and keeps particles out of the eyes and nose. Skin The Dermis (Nails) A grows from living cells in the nail root at the base of the nail. As new cells form, the nail grows longer. Nails protect the tips of your fingers and toes. So, your fingers and toes can be soft and sensitive for a keen of touch. Skin Caring for Your Skin Because your skin has so many vital functions, taking care of it is important. Three simple habits can help you keep your skin healthy. Eat a healthful diet. Keep your skin clean and dry. Limit your exposure to the sun.

Healthful Diet Your skin is always active. Eating a well balanced diet provides the energy and raw materials needed for the growth and replacement of hair, nails, and skin cells. In addition to what you eat, a healthful diet also includes drinking plenty of water. That way, you can replace the water lost in Perspiration. Skin Caring for Your Skin Keeping Skin Clean When you wash your skin with mild soap, you get rid of dirt and harmful bacteria. Washing your skin also helps to control oiliness. Good washing habits are particularly important during the teenage years when oil glands are more active. When glands become clogged with oil, the black heads and whiteheads of can form. If acne becomes infected by skin bacteria, your doctor may prescribe an antibiotic to help control the infection. Skin Caring for Your Skin Limiting Sun Exposure It is important to protect your skin from the harmful effects of the sun. Repeated exposure to sunlight can damage skin cells, and possibly to . Skin Caring for Your Skin Cancer is a disease in which some cells in the body divide uncontrollably. In addition, repeated exposure to the sun or UV radiation can cause the skin to become leathery and wrinkled.

Is it skin cancer? Try A B C D! Skin Caring for Your Skin There are many things you can do to protect your skin from damage by the sun. When you are outdoors, always wear a hat, sunglasses, and use a sunscreen on exposed skin. Choose made of tightly woven fabrics for the greatest protection. In addition, avoid exposure to the sun between the hours of 10 A.M. and 4 P.M. That is the time when sunlight is the strongest. Skin to Your Skin Bruises These occur when blood vessels under the skin burst but skin stays in tact. The red blood cells leak into tissues and a chemical called hemoglobin is released. Hemoglobin is responsible for the different colors of bruises. Skin Injuries to Your Skin Cuts These occur when there is a tear in the skin, normally produce by a sharp edge. are formed when large amounts of build under a cut. Skin Repairs to the Skin Skin Grafts When pieces of skin cut from one part of the body and put on another part that was injured or burned. The process by which an internal environment is kept stable in spite of changes in the external environment is called

A. Healing B. Digestion C. Homeostasis D. How does the skin protect the body from disease?

A. By keeping disease-causing microorganisms from entering the body B. By gathering information about the environment C. By increasing body temperature when it is cold D. By supplying water to the body through the pores How does the skin help regulate body temperature?

A. By removing wastes from the body B. By blocking information about the environment C. By enabling excess heat to escape the body D. By allowing body temperature to change when the weather becomes warmer or cooler Washing your skin helps prevent

A. Skin cancer B. C. Chapping D. Acne Nerves and blood vessels in the skin are located in the

A. Pores B. Dermis C. Epidermis D. Canals The pigment melanin in the skin functions to

A. Keep water within the skin B. Produce new living cells in the epidermis C. Help protect the skin from sunburn D. Surround and protect hair follicles The epidermis is the outermost layer of the skin

A. True B. False Three simples habits can help you keep your skin healthy. Select all that apply

A. Eat a healthful diet B. Keep your skin clean and dry C. Never wash your hands D. Limit your exposure to the sun The more melanin in your skin, the darker it is

A. True B. False The epidermis has millions of nerves or blood vessels running through it.

A. True B. False