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15 16 Learning About the Circulatory System What’s In Your Blood? If you drained out all your blood, you could fill a 5-liter bucket. Every cell in your body depends on blood to deliver food and oxygen and to carry away wastes. Blood is the key to keeping all the cells of your body alive. There are four components to the blood: plasma, red blood cells, white blood cells and platelets. The plasma is mostly water and its function is to carry all the other components through the body. It is pale yellow and contains some sugar, protein, minerals and waste materials. The platelet’s function is to keep you from bleeding to death by making a clot (we call it a scab) and keeping the blood from flowing out a cut. They are about 1/3 the size of red blood cells, live for 7 – 9 days, and are produced in the bone marrow. You have about 15 trillion red blood cells (RBC). The function of the RBC is to transport the oxygen from the lungs to the cells. They are mostly made of hemoglobin, which is an ironcontaining protein that binds chemically to oxygen molecules. RBC do not have a nucleus so they can only live about 120 days. The function of the white blood cells (WBC) is to attack germs and other invaders that get into the body. Some white blood cells recognize disease-causing organisms and others produce chemicals to fight the invaders. WBC differ from RBC in several ways. There are fewer of them – 1 WBC for every 500 to 1,000 RBC’s. They are much bigger than RBC, have a nucleus, and can live for months or even years. Fun facts about the Circulatory System Every second about 2 million red blood cells die. Your heart pumps about 4,000 gallons of blood each day. It takes about 1 minute for the blood to circulate throughout your body. An average human’s heart beats 30 million times per year. The sound of a heartbeat is created by the valves in the heart closing as they push blood through its chambers. There are 5 million red blood cells, 10,000 white cells and 250,000 platelets in a pinhead-size drop of blood. Materials: colored pencils, model of the blood What To Do: 1. Look at the diagram of the blood. 2. The red blood cells look like donuts. Color them red. 3. The white blood cells are larger than the red cells. Don’t color them 4. The platelets are very small and are clear in the blood. Color them purple. 5. Color the plasma around the blood cells yellow. Scientists use models and pictures to represent ideas and objects too big or too small to see with the unaided eye. The microscope aids our eyes in seeing very small things and the telescope aids our eyes to observe objects that are very far away. When we use models there are problems with size, scale, color and materials. These problems are called limitations. Questions: 1. What is a limitation of the model of blood we used? ________________________________________________ 2. What is a limitation of the picture we used? ________________________________________________ Why does your blood look blue/green? Some people think that the blood inside them is blue. That is not true. You have RED blood cells not blue. This is what happens. Your skin is thin and acts like a filter. Typical light has all the colors of the rainbow in it. When light goes through your skin and hits the blood vessels it bounces back out but the red is filtered by your skin leaving only the blue and yellow from the rainbow. This blue/green color is what we see. 17 Color in the diagram as your teacher does on the overhead. Materials: ½ straw with red water, clay, petri dish, milk What To Do: 1. Your teacher will show you ½ a straw that has been filled with red food coloring. 2. Your teacher will place it in the petri dish and begin covering it with milk. 3. Observe the color of the straw when covered with milk. Questions: 1. What color do you observe the straw to have? ________ 2. What made it change color? ______________________ _____________________________________________ 3. What does the milk represent? ____________________ 4. Why do you see a different color than red? ___________ _____________________________________________ Your heart will be red. Your arteries will also be red as they carry oxygen rich blood away from your heart. Your veins will be blue as they carry oxygen poor blood (carbon dioxide rich) back to your heart. Listening to Our Hearts Your heart is mostly muscle tissue. It has only one function. Day and night, twenty-four hours a day, your heart pumps blood to every part of your body. Your circulatory system functions to help control your temperature, to fight disease, to carry oxygen, nutrients, and water to your cells, and to carry away waste from your cells. Every time your heart beats, the blood is being squeezed out of the heart, into an artery and out to the body. The arteries take the blood away from the heart where they connect with the smallest blood vessels called capillaries. Capillaries are microscopic blood vessels that allow materials to pass through them to the cells by diffusion. The capillaries connect with the veins, which take the blood back to the heart. Label the diagram with the following words. 1. Heart 3. Artery 2. Vein 4. Capillary 18 Materials: stethoscope, alcohol, cotton balls What To Do: 1. Clean the earpiece of the stethoscope with alcohol and a cotton ball. 2. Use the stethoscope to listen to your heart. 3. Listen for two different sounds. 4. Doctors call the sounds the “LUB” and “DUB.” See if you can hear them. 5. A LUB and a DUB make one heartbeat. 6. Switch with your partner so they can listen to their heartbeat. Questions: 1. What is the function of the heart? __________________________ 2. What sounds does the heart make? _________________________ 3. Why is blood such an essential fluid to the circulatory and respiratory systems? _______________________________________________________ _______________________________________________________ 4. How do arteries differ from veins? ________________________ _______________________________________________________ 5. How does the function of capillaries fit into the circulatory system?_________________________________________________ _______________________________________________________ 80 19-a Name _________________period _____ date______ EXIT TICKET - Circulatory System 1. What color is your blood? A. blue B. yellow C. green D. red 2. What is the function of the circulatory system? A. Deliver food to your cells B. Take wastes away from your cells C. Take oxygen to your cells D. All of the above 3. What is a limitation of a model? A. A grade B. A problem in size or scale C. The builder of the model D. All the correct things found on the model Conclusion: Red blood cells carry the ____________ to all cells of the 19-b Name _________________period _____date______ EXIT TICKET- Circulatory System 1. What is the function of the circulatory system? A. Deliver food to your cells B. Take wastes away from your cells C. Take oxygen to your cells D. All of the above 2. What color is your blood? A. blue B. yellow C. green D. red 3. What is a limitation of a model? A. A grade B. A problem in size or scale C. The builder of the model D. All the correct things found on the model body. __________ blood cells attack invaders. Conclusion: (blood, platelets, oxygen, white, plasma) Red blood cells carry the _________ to all cells of the body. ____________ is the liquid that carries all the other _______ blood cells attack invaders. ________ is the liquid components of blood. The component of the blood that that carries all the other parts of blood. The component of causes it to clot is the ____________. the blood that causes it to clot is the ____________.