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The Heart and Circulatory System 1 of 49 © Boardworks Ltd 2004 Contents The Heart and Circulatory System The circulatory system Structure of the heart 2 of 49 © Boardworks Ltd 2004 How do substances move around the body? The body has its own transport system that carries substances around the body. Which organs are involved in this system? heart blood vessels blood The body’s transport system is called the circulatory system. Why is it given this name? 3 of 49 © Boardworks Ltd 2004 What is carried by the circulatory system? Which gases are transported to and from the body’s cells by the blood flowing in the circulatory system? carbon dioxide oxygen Oxygen is the gas needed for respiration and is transported to the body’s cells. Carbon dioxide is the waste gas produced by respiration that must be carried away from the body’s cells. 4 of 49 © Boardworks Ltd 2004 Two types of blood The circulatory system carries two types of blood: oxygen-rich blood oxygen-poor blood blood travelling c to the body cells blood travelling away from the body cells high oxygen content low oxygen content low carbon dioxide content high carbon dioxide content The arrangement of the circulatory system means that these two types of blood do not mix. Why is this important? 5 of 49 © Boardworks Ltd 2004 At the heart of the circulatory system The heart is the organ at the centre of the circulatory system. It pumps blood around the body. How are the two types of blood (oxygen-rich and oxygen-poor) kept apart inside the heart? 6 of 49 © Boardworks Ltd 2004 Inside the heart The inside of the heart is divided into two sections so that the two types of blood (oxygen-rich and oxygen-poor) are kept apart. right side of the heart left side of the heart oxygen-poor blood oxygen-rich blood Remember that the heart is always labelled as if it is in a body facing you, so the right side of the heart is on the left of the diagram. 7 of 49 © Boardworks Ltd 2004 The two sides of the heart 8 of 49 © Boardworks Ltd 2004 How does blood circulate around the body? Blood is pumped around the body by the heart. It takes about 30 seconds for blood to go once around the body. Starting with the left side of the heart, what route does the blood follow to complete one circuit of the body? 9 of 49 © Boardworks Ltd 2004 How does blood circulate around the body? The left side of the heart pumps oxygen-rich blood to the rest of the body. This blood supplies the body’s cells with oxygen. What gas does the blood then pick up from the body’s cells and where does the blood go next? 10 of 49 body’s cells © Boardworks Ltd 2004 How does blood circulate around the body? Blood picks up carbon dioxide from the body’s cells. This oxygen-poor blood then travels back to the right side of the heart. The oxygen-poor blood needs to lose the carbon dioxide and pick up more oxygen. How does it do this? 11 of 49 body’s cells © Boardworks Ltd 2004 How does blood circulate around the body? Next, the right side of the heart pumps oxygen-poor blood to the lungs. lungs In the lungs the blood gets rid of the waste carbon dioxide and collects more oxygen. Where does this oxygen-rich blood then travel to? 12 of 49 body’s cells © Boardworks Ltd 2004 How does blood circulate around the body? The oxygen-rich blood then returns to the left side of the heart. lungs This completes the blood’s journey around the body. Why is the journey of blood through the circulatory system called a double circulation? 13 of 49 body’s cells © Boardworks Ltd 2004 A double circulatory system During one complete circuit of the body, blood passes through the heart twice. lungs The heart has two jobs to do and so the circulatory system involves a double circulation. What are the two jobs that the heart carries out during this double circulation? 14 of 49 body’s cells © Boardworks Ltd 2004 Which way does blood flow? 15 of 49 © Boardworks Ltd 2004 Contents The Heart and Circulatory System The circulatory system Structure of the heart Valves in the heart How the heart pumps blood Summary quiz 16 of 49 © Boardworks Ltd 2004 The structure of the heart – exterior The heart pumps blood around the circulatory system. What is the heart made of? muscle tissue The heart is made of muscle and keeps pumping blood around your body, even when you are asleep! What do the blood vessels on the outside of the heart do? 17 of 49 © Boardworks Ltd 2004 The heart needs blood too! The heart is full of blood but also needs its own blood supply so that the muscle can keep pumping. muscle tissue blood vessels supply blood to muscle tissue The blood vessels on the outside of the heart carry oxygen-rich blood to the heart muscle cells. Oxygen-poor blood is then carried away from these cells by outer blood vessels and back into the heart. 18 of 49 © Boardworks Ltd 2004 The structure of the heart – interior The inside of the heart is divided into two sections to keep oxygen-rich and oxygen-poor blood separate. Each side of the heart is also divided into two sections. right side of the heart left side of the heart Each section of the heart is called a chamber. How many chambers are there? 4 19 of 49 © Boardworks Ltd 2004 The chambers of the heart The four chambers of the heart have special names: An upper chamber is called an atrium (plural atria). right atrium left atrium right ventricle left ventricle A lower chamber is called a ventricle. 20 of 49 © Boardworks Ltd 2004 What do atria and ventricles do? The chambers of the heart have different functions. blood to the lungs blood from the body blood to the body blood from the lungs The atria collect blood that enters the heart. The ventricles pump blood out of the heart. 21 of 49 © Boardworks Ltd 2004 Inside the heart – labels 22 of 49 © Boardworks Ltd 2004 Inside the heart – labelling activity 23 of 49 © Boardworks Ltd 2004 Chambers of the heart – activity 24 of 49 © Boardworks Ltd 2004