Science 4 Notes 5 PDF

ENGLISH ELEMENTARY DEPARTMENT 1ST Grading Period S.Y. 2024 - 2025 SCIENCE FOUR LESSON 4.1...

ENGLISH ELEMENTARY DEPARTMENT 1ST Grading Period S.Y. 2024 - 2025 SCIENCE FOUR LESSON 4.1 YOUR BODY’S COVER The skin that covers your body today is not the same skin you had last year. Your skin grows as you grow. To help you understand how large your skin is, measure the length of your arm and the distance around it. Cut a piece of paper this size for each arm. Measure the length and the distance around one of your legs and cut a piece of paper this size for each leg. Measure your head and trunk and cut pieces of paper to these sizes. Now lay the pieces of paper on the floor. If your skin were spread out flat, it would cover about this same area. Like the rest of your body, the skin is made up of tiny parts called cells. Your skin makes millions of new cells each day to replace dead cells that are constantly being rubbed off. If your skin gets cut or burned, new skin grows to make your cover whole again. Your skin also regulates the temperature of your body, protects your body from injury, guards against pathogens (germs), helps heal cuts, helps remove wastes from your body, stores water and excess energy, and produces vitamin D. Your outer skin Your skin, which God designed as a protection for your body, is made up of three layers. The outer skin, or epidermis [ěp/i dûr'mis], contains no blood vessels. It is made up of twelve to fifteen layers of cells. The lower cells in the epidermis are alive; they keep making new cells, which push the old ones upward. The cells become flatter and drier as they are pushed toward the surface of the skin. Tiny flake of dead skin falls off when you wash, rub, scratch, or scrape your skin. Various thicknesses Not all your skin is the same thickness; in some places it is very thick-feel the skin on the palm of your hand. In other places your skin is very thin. Gently feel the skin on your eyelid or pinch the skin on the back of your hand. The parts of your skin that get the roughest treatment have the thickest epidermis. An extra thick, hard layer of epidermis called a callus develops when there is constant rubbing or pressure. A callus will go away gradually when the rubbing or pressure is stopped. Excessive rubbing may cause a blister, a raised part of epidermis that is filled with a watery substance. First, the injured part of the skin is very tender and sore, and if the blister is not cared for properly, it can become infected. Because unbroken skin over a blister helps protect the deeper layers of skin from infection, you should try not to break most blisters. Carefully wash the skin around a blister with warm, soapy water, and then cover it with a sterile (free from pathogens) bandage. Bandages which are wrapped in paper are sterilized (made sterile) by heat. If the blister is broken, you should watch for signs of infection – redness, swelling, pus, and throbbing pain. A blister located where rubbing will continue, such as on a foot, should be opened and drained. After the blister is carefully washed, clean a needle with an antiseptic such as rubbing alcohol or hydrogen peroxide [hi'drǝ jǝn pǝ rõk'sid']. An antiseptic destroys many pathogens and thus helps prevent infection. Prick one side of the blister with the sterilized needle and gently press the opposite side to force out the fluid. Do not remove the skin. Page 1 of 5 Additional protection Your hair and nails are also the epidermis. Your nails are hard and tough to protect the tips of your fingers and toes. The whitish, half-moon area at the base of a nail is part of the root from which new nail cells grow. As new nail cells form, the older cells are pushed outward and harden to form the nail. The ends of your nails are made up of dead cells; thus, when you trim your nails, you feel no pain because only dead nail cells are cut. Your hair protects your body, too. It protects your head from heat, cold, and too much sun. Your eyebrows keep per- spiration out of your eyes, and your eye- lashes prevent dust and dirt from entering your eyes. New cells at the root of each hair push the old cells toward the surface. As the old cells are pushed out, they die and form the hair that you see. Does it hurt when your hair is cut? Pull a few hairs on your arm. How do you know that roots contain live cells? Not all your skin contains the same amount of melanin; therefore, some parts of your skin are darker than others. Do you have any freckles? Sometimes the melanin collects in little spots, making the spots darker than the rest of the skin. Being outside in the sunshine causes melanin to build up and the skin to darken temporarily. This tanning of the skin is especially noticeable in white skin. The purpose of color Skin color is one of God's special ways of caring for people. In areas close to the equator where it is extremely hot, the sun shines with direct rays, and thus the people are exposed to many ultraviolet [ŭl/trǝ vi'ǝ lit], or harmful, rays of the sun. When God scattered the people from the Tower of Babel "upon the face of all the earth" (Gen. 11:9), some of them settled near the equator on the continent of Africa. God provided these people with the ability to produce a large amount of melanin, making their skin very dark. The melanin in the epidermis helps prevent the sun's ultraviolet rays from harming the rapidly multiplying cells of the lower epidermis. The darker the skin color, the greater the amount of melanin, and thus the more protection the epidermis gives from ultraviolet rays. People now living in North America whose ancestors were from Africa have inherited the ability to produce large amounts of melanin. Their dark skin is a testimony of God's provision for their forefathers. The people who traveled from the Tower of Babel to the continents of Europe or northern Asia were far from the direct rays of the sun. Because they needed little protection from the sun, they had less melanin than people with darker skin; thus, their skin was fair (light-colored). People with different skin colors have now spread to most parts of the world. A few people – called albinos [ăl bi'nōz] – have no pigment in their skin. Albinos have very light skin, white hair, and the colored parts of their eyes are pink. Because albinos have no protective melanin, they must be very careful to protect their skin and eyes from the sunlight. Your real skin Much of your skin's work is done in the layer of skin beneath the epidermis. This layer of skin – the dermis – contains connective tissue, blood vessels, nerve endings, hair follicles, oil glands, and sweat glands. The connective tissue makes your skin elastic and strong; it also attaches your skin to your muscles. Blood vessels in the dermis carry food and food and oxygen to the new skin cells. When the dermis is cut, your skin bleeds, and you feel pain. The root of the hair Hair grows on most parts of your body except on the palms of your hands and on the soles of your feet. The live cells, or root, of each hair grow in a hair follicle little sac called a hair follicle. As long as the hair follicle is alive, a hair grows. Hair follicles sometimes die or are destroyed by disease, and baldness occurs. Do you ever have "goose-bumps"? There are little muscles at the root of every hair. If you feel cold or excited or are suddenly frightened, these tiny muscles contract, and the hairs stand straight up, causing goose bumps. Page 2 of 5 Curly or straight hair The texture and curliness of your hair are determined by the shape of the hair follicles. If the follicles are round and straight, the hair will be straight; if the follicles are flattened and curved, the hair will be curly. The extent of the curl depends on the flatness and the curve of the follicle. Three Layers of the Skin 1. EPIDERMIS It is the outer part or top layer of the skin that makes up its strong protective covering. It has no blood vessels. It provides a waterproof barrier and creates outer skin tone. It is made up of twelve to fifteen layers of cells 2. DERMIS It is the layer of skin beneath the epidermis. It is in the dermis where most of the structures of the skin are located, such as various types of glands and hair follicles. It is composed of fibrous and cellular connective tissue elements that contains nerve and vascular layer of skin. The connective tissue is responsible for the skin's elasticity and strength, as well as its attachment to the muscle. It contains blood vessels which feeds the skin, removes toxins, and supply epidermis with blood. It contains nerve endings, hair follicles, oil glands, and sweat glands. 3. SUBCUTANEOUS LAYER It is also known as hypodermis and is found below the dermis. It is the fatty layer of the skin that stores energy. It varies in thickness from one part of your body to another. It protects your muscles and bones from jolts, bumps, and falls. It helps hold in your heat during cold weather. It helps keep your body from getting too warm or too cold. It helps insulate the body, helping to maintain its stable temperature. The color of hair The color of your hair is determined by the pigment that is deposited in new hair cells before they grow out of a follicle. Red hair contains an iron pigment that is not found in any other color of hair. As people grow older, pigment is no longer deposited in the new hair cells on the head; and the hair gradually loses its color. Tiny bubbles of air in the hair make it look white. A mixture of pigmented and unpigmented hair usually appears gray. Scientists have not yet discovered why hair loses its color. A layer of padding Below the dermis lies the subcutaneous [sub kyoo tā ne ǝs] layer of skin – a fatty layer that stores energy. Like the epidermis, the subcutaneous layer varies in thickness from one place on your body to another. This fat layer cushions your muscles and bones against shocks and jolts, and during cold weather, it helps hold in your body heat. Page 3 of 5 Your skin at work: Preventing dryness The dermis contains Sebaceous glands (oil glands) which are connected to the hair follicles. The sebaceous glands produce an oily substance called sebum. Sebum, which is released through the hair follicles to the surface of the skin, spreads over the surface of the skin to keep it smooth and soft. This thin layer of oil that covers your entire body helps water- proof your body and prevents too much water from evaporating through your skin. If you stay out in the sun too long, your skin becomes dry because the sun dries the sebum faster than the dermis can make it. Wind also dries the sebum on your skin. If the skin does not have sufficient oil, it becomes so dry that it cracks. Controlling your temperature Your skin contains two to three million sweat glands, which help your body to maintain a normal temperature of about 98.6 °F. Sweat glands are very plentiful under your arms, on the palms of your hands, on the soles of your feet, on your back, and on your forehead. Sweat, or perspiration, travels from the sweat glands through tiny tubes leading to pores (tiny openings) in the epidermis. Although the sweat glands remove some waste from your body, their main purpose is to cool your body as the perspiration evaporates. These glands never stop working. The perspiration usually evaporates into the air before it collects in drops; however, on hot days or whenever you are involved in strenuous activity, large drops of perspiration often form on your skin. Sometimes when the weather is humid, perspiration collects on the skin faster than it evaporates. As a result, you feel hotter than on a less humid day. The blood vessels in your skin help keep your body temperature normal, too. As food is broken down in your body, energy and heat are produced. Vigorous exercise also makes heat in your body. Some of this heat passes to the outside air through the blood vessels in your skin. When you get too warm, the tiny blood vessels in your skin expand so that more blood can flow into them. Some of the extra heat from the blood then passes through the skin to the outside air. Whenever your body gets cold, the blood vessels in your skin contract. Then less blood flows into the skin, and a smaller amount of heat passes through the skin to the outside air. Keeping out bacteria Your skin normally has no openings except natural ones, such as your nose and mouth and the pores in the epidermis which lead to the sweat glands and the oil glands in the dermis. The skin is such an excellent covering for your body that it prevents disease-causing bacteria (pathogens) from getting into your body. Without the protection of your skin, harmful bacteria that are in the air and on every object, you touch would enter your body and kill you in just a few hours. Even a tiny break in your skin, such as a cut or a scratch, allows some harmful bacteria to enter your body. Do you remember what to do before treating any injury? After washing your hands thoroughly, you should clean the cut or scratch with soap and warm water. If the skin is torn, it can become infected easily, so be sure that the wound is cleansed well. An abrasion (scrape) should be cleaned with soap, warm water, and sterile cotton or gauze. Wipe the cotton or gauze from the center of the abrasion away from the wound to wash out dirt and pathogens. If possible, rinse a cut, scratch, or abrasion under running water. After rinsing the wound thoroughly, carefully blot it dry and cover it with a sterile bandage. Healing injuries When you get a cut or a scratch, the blood vessels in the skin contract to stop the flow of blood. A clot of blood begins to form and fill the injury; platelets in the blood stick to each other and to scab both sides of the cut. Because the blood clot (scab) is a protection for the wound, you should not pick it off. As the blood clot shrinks, the two sides of the cut are pulled closer together. Later, new skin cells growing from each side of the cut join together. A scar sometimes remains where the skin cells are joined. Page 4 of 5 Producing vitamin D Cholesterol is a substance which is manufactured in the liver and is normally found in the blood, brain, nerves, and skin. When ultraviolet rays of the sunshine on your skin, they change cholesterol in your skin into vitamin D. This is why vitamin D is sometimes called the sunshine vitamin. Remember that God provided large amounts of melanin to the groups of people who would settle near the equator when mankind spread out from the Tower of Babel. Because of this protection, these dark-skinned people could work long hours in the sun, producing sufficient vitamin D from the ultraviolet rays without causing overexposure to them. Dark-skinned people now living in colder climates, which lack the direct rays of the sun, often lack sufficient vitamin D. Anyone spending too little time in the sunshine cannot produce sufficient vitamin D for healthy teeth and bones. Such people must be sure to eat foods which contain this vitamin. For good food sources of vitamin D, refer to the chart of nutrients on pages 10 and 11. If you lack sufficient vitamin D, it will show in the structure of your teeth and bones. A lack of vitamin D can also cause rickets, a disease in which the bones become weak, causing irregular growth and deformities. Storing energy You know that your energy comes from nutrients in the food you eat. Most energy that is not used is stored as fat in the subcutaneous layer of the skin to be used at a later time. Whenever your body requires extra energy, some of the stored energy is returned to your blood and carried to the parts of your body that need it. If a person is overweight, the subcutaneous layer is storing too much energy. References: https://www.google.com/search?q=5+skin+diseases&rlz=1C1SQJL_enPH911PH911&oq=&aqs=chrome.2.35i3 9i362l8...8.89927107j0j15&sourceid=chrome&ie=UTF-8 https://open.oregonstate.education/aandp/chapter/5-3-functions-of-the-integumentary-system/ Shimmin, Dolores, et.al Developing Good Health 3rd Edition, A Beka Science/ Health Series, Pensacola Christian College, Pensacola, Florida, USA Page 5 of 5