The Human Heart: The Most Important Muscle in the Human Body

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1 The Human Heart: The Most Important Muscle in the Human Body (1) As you have already learned, there are muscles all over your body. All of them are important, but not all of them are vital. The muscle you cannot do without is inside your chest. It is the heart! (2) The heart is responsible for two things. First, through the blood it pumps, the heart provides oxygen and nutrients to our cells to keep us alive. Second, and again through the blood, it carries away wastes from these active cells to special organs that rid them from our bodies. (3) The heart is really a pump, or two pumps in one. The right side receives blood from the body and pumps it to the lungs. The left side does the opposite: it receives blood from the lungs and pumps it around the body. The Beat Goes On! (4) The heart is a involuntary muscle. This means it works on its own without us having to think about any of its average one hundred thousands beats daily. With each beat, your heart fills with blood. Then it contracts to pump the blood through your body. This is done all day, all night, all the time. Heart Parts (5) The heart has four different hallow areas called chambers. There are two chambers on each side of the heart. Each one is separated by a valve, a flap of tissue that opens and closes to keep the blood flowing in the right direction.

2 (6) The two chambers on top are called the atria (ay-tree-ah). The atria are the chambers that fill with blood. The two chambers on the bottom are called the ventricles (ven-trick-ulz). They pump the blood out of the heart, first to the lungs and later to the rest of the body. Separating the two sets of chambers is a thick wall of muscle called the septum (say: sep-tum). The septum's job is to separate the left side and the right side of the heart. (7) The atria, ventricles and valves work together to pump blood. The atria fill with blood, then pump it into the ventricles. The ventricles pump blood out of the heart. Recycling (8) The blood in our bodies is used over and over again. Its movement through the heart and around the body is called circulation and can be viewed as a cycle. (9) Beginning at the left side of your heart, fresh, clean oxygen-rich blood is pumped around our bodies. The cells through-out our bodies removes the oxygen from the blood and use it, like fuel, to work and grow. In these processes, the cells creates carbon dioxide and other wastes that must be removed to keep the cells healthy. The blood is responsible for picking up this waste, delivering it to the kidneys where, except for the carbon dioxide, it is removed from the blood. (10) The blood with its load of carbon dioxide returns to the right side of the heart where it is then pumped to the lungs to get rid of the carbon dioxide and to pick-up fresh oxygen. The oxygen-rich blood goes back to the left side of the heart and is then pumped around the body to complete the cycle. Amazingly, it all happens in less than half a minute!

3 Networks (11) The heart uses a network of tubes to get blood throughout the body. These tubes are called blood vessels. The blood vessels that carry blood away from the heart (the fresh blood that's full of oxygen) are called arteries, and the ones that carry blood back to the heart (the stale blood that's carrying the waste) are called veins. Listen to the Lub-dub Amazing Facts About the Human Heart It is about the size of a fist. It beats on average 70 times per minute. That s 4200 per hour, approximately one hundred thousand beats per day, 365 million beats per year and about 30 billion beats in an average life time of 80 years. An adult heart pumps 7,500 litres of blood daily. It takes 20 seconds to pump blood to every cell in your body. Blood is cleaned by the kidneys. If you lined up all the blood vessels in your body end to end, they would wrap around the earth twice! (12) When you go for a checkup, your doctor uses a stethoscope to listen carefully to your heart beat. A healthy heart makes a "lub-dub" sound with each beat. This sound comes from the valves shutting inside the heart. The first sound (the "lub") happens when the blood hits valves between the atria and ventricles. The next sound (the "dub") happens when the blood hits the aortic and pulmonic valves that close up as the heart relaxes to fill with blood for the next beat. Where s My Pulse? (13) You can feel your heart beating in several different areas of the body. The most common place used is the wrist just below your thumb. You'll know that you've found your pulse when you can feel a small beat under your skin. Each beat is caused by the contraction of your heart. If you want to find out what your heart rate is, use a watch with a second hand and count how many beats you feel in one minute.

4 Keep Your Heart In Shape (14) Most children are born with a healthy heart and it's important to keep yours in good shape. Here are some things that you can do to help keep your heart strong and healthy. (15) Remember that your heart is a muscle. Just like you need to exercise your leg and arm muscles, you need to exercise your heart, too. Regular exercise is a great way to keep your heart in shape. At least 15 to 20 minutes of exercise each day will give your heart the workout it needs to be the strongest muscle it can be. (16) Eating a variety of healthy foods is great for your heart. Avoiding a lot of fatty foods will keep your heart happy, too. (17) Stay away from smoking! Smoking is bad for every part of your body, and especially your heart. Your heart and blood vessels hate cigarettes, because smoking makes their jobs much harder.

5 Comprehension The Human Heart Worksheet 1. What are the responsibilities of the heart? 2. What does the left side and the right side of the heart do? 3. What is the source of the sound in your heart beat? 4. What can you do to keep your heart healthy? 5. What happens to the blood in the lungs? Vital Statistics About the heart a. Average number of beats for an adult heart... b. Number of litres of blood heart pumps daily... c. Number of chambers in the heart... d. Length of time to pump blood to every cell in the body... e. Amount of blood that goes through kidneys for cleaning... f. Number of minutes of exercise required daily to keep heart healthy Number the steps in the heart s process of pumping blood correctly. When this blood reaches the cells, it provides them with oxygen and picks up carbon dioxide and other wastes. The blood is then pumped to the body, stopping by the kidneys for the removal of the other wastes along the way. It is then pumped from the heart to the lungs where it gives up the carbon dioxide and picks up oxygen. The oxygen rich blood then returns to the heart right atrium. First, blood is pumped around the body from the left ventricle. The blood, now full of waste returns to the heart left atrium.

6 Backbone Puzzle on the Human Heart 1 p 2 t 3 x 4 d 5 a 6 i 7 t 8 h 9 s 10 u 11 t 12 l 13 v 14 n 1. Instrument used to listen to the heart. 2. Considered the most important muscle in the body minutes of this each day will help keep your heart healthy. 4. A waste gas given off by body cells. 5. The heart chambers that receive blood. 6. Name given to the squeezing action of the heart. 7. The heart is this type of muscle. 8. The four hallow sections of the heart. 9. Tubes that carry blood around the body. 10. The movement of blood around the body. 11. The wall that separates the left and right sides of the heart. 12. The heart beat felt in the wrist. 13. These four doors control direction of blood flow through the heart. 14. Chambers the pump bllod away from the heart. The system that includes the heart and lungs is also called the system.

7 Diagram of the human heart. G Add the following labels. Some labels may be used more than once. pulmonary artery pulmonary vein septum valve aorta left ventricle right ventricleleft atrium right atrium G G Colour the vessels that bring blood to the body red. Colour the vessels that bring blood to the heart blue.