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© Boardworks Ltd 2004 1 of 49 KS4 Biology The Heart and Circulatory System.

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Presentation on theme: "© Boardworks Ltd 2004 1 of 49 KS4 Biology The Heart and Circulatory System."— Presentation transcript:

1 © Boardworks Ltd of 49 KS4 Biology The Heart and Circulatory System

2 © Boardworks Ltd of 49 How the heart pumps blood The Heart and Circulatory System The circulatory system Structure of the heart Valves in the heart Summary quiz Contents

3 © Boardworks Ltd of 49 Which organs are involved in this system? How do substances move around the body? The body has its own transport system that carries substances around the body. The bodys transport system is called the circulatory system. Why is it given this name? heart blood vessels blood

4 © Boardworks Ltd of 49 What is carried by the circulatory system? carbon dioxide oxygen Which gases are transported to and from the bodys cells by the blood flowing in the circulatory system? Oxygen is the gas needed for respiration and is transported to the bodys cells. Carbon dioxide is the waste gas produced by respiration that must be carried away from the bodys cells.

5 © Boardworks Ltd of 49 The arrangement of the circulatory system means that these two types of blood do not mix. Why is this important? Two types of blood The circulatory system carries two types of blood: oxygen-rich blood c oxygen-poor blood blood travelling to the body cells high oxygen content low carbon dioxide content blood travelling away from the body cells low oxygen content high carbon dioxide content

6 © Boardworks Ltd of 49 How are the two types of blood (oxygen-rich and oxygen-poor) kept apart inside the heart? 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.

7 © Boardworks Ltd of 49 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. oxygen-poor blood right side of the heart oxygen-rich blood left side of the heart 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.

8 © Boardworks Ltd of 49 The two sides of the heart

9 © Boardworks Ltd of 49 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?

10 © Boardworks Ltd of 49 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 bodys cells with oxygen. What gas does the blood then pick up from the bodys cells and where does the blood go next? bodys cells bodys cells

11 © Boardworks Ltd of 49 The oxygen-poor blood needs to lose the carbon dioxide and pick up more oxygen. How does it do this? How does blood circulate around the body? Blood picks up carbon dioxide from the bodys cells. This oxygen-poor blood then travels back to the right side of the heart. bodys cells bodys cells

12 © Boardworks Ltd of 49 lungs Where does this oxygen-rich blood then travel to? How does blood circulate around the body? Next, the right side of the heart pumps oxygen-poor blood to the lungs. In the lungs the blood gets rid of the waste carbon dioxide and collects more oxygen. bodys cells bodys cells

13 © Boardworks Ltd of 49 The oxygen-rich blood then returns to the left side of the heart. This completes the bloods journey around the body. Why is the journey of blood through the circulatory system called a double circulation? How does blood circulate around the body? bodys cells bodys cells lungs

14 © Boardworks Ltd of 49 During one complete circuit of the body, blood passes through the heart twice. 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? A double circulatory system bodys cells bodys cells lungs

15 © Boardworks Ltd of 49 Which way does blood flow?

16 © Boardworks Ltd of 49 The Heart and Circulatory System The circulatory system Structure of the heart How the heart pumps blood Valves in the heart Summary quiz Contents

17 © Boardworks Ltd of 49 The structure of the heart – exterior The heart pumps blood around the circulatory system. What is the heart made of? The heart is made of muscle and keeps pumping blood around your body, even when you are asleep! muscle tissue What do the blood vessels on the outside of the heart do?

18 © Boardworks Ltd of 49 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. 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. muscle tissue

19 © Boardworks Ltd of 49 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. Each section of the heart is called a chamber. How many chambers are there? right side of the heart left side of the heart 4

20 © Boardworks Ltd of 49 The chambers of the heart The four chambers of the heart have special names: A lower chamber is called a ventricle. An upper chamber is called an atrium (plural atria). right ventricle right atrium left ventricle left atrium

21 © Boardworks Ltd of 49 What do atria and ventricles do ? The chambers of the heart have different functions. The atria collect blood that enters the heart. The ventricles pump blood out of the heart. blood to the body blood from the body blood to the lungs blood from the lungs

22 © Boardworks Ltd of 49 Inside the heart – labels

23 © Boardworks Ltd of 49 Inside the heart – labelling activity

24 © Boardworks Ltd of 49 Chambers of the heart – activity

25 © Boardworks Ltd of 49 The Heart and Circulatory System The circulatory system Structure of the heart How the heart pumps blood Valves in the heart Summary quiz Contents

26 © Boardworks Ltd of 49 Preventing backflow Blood always flows in the same direction as it moves through the heart during each circulation of the body. Why is it important that blood does not flow backwards?

27 © Boardworks Ltd of 49 The chambers of the heart are separated by valves which prevent blood from flowing in the wrong direction. Heart valves There are valves between the atria and the ventricles… …and there are valves leading out of the ventricles. valve between right atrium and right ventricle valve between left atrium and left ventricle valve leading out of right ventricle valve leading out of left ventricle

28 © Boardworks Ltd of 49 Naming the heart valves

29 © Boardworks Ltd of 49 How are valves held in place? The valves between the atria and ventricles are connected to the inner walls of the heart by tough tendons. valve open

30 © Boardworks Ltd of 49 How are valves held in place? The tendons allow the valves to close and hold the valve flaps in place. They prevent the valves from flipping up and turning inside out. Why is this important? valve open valve closed

31 © Boardworks Ltd of 49 How do valves work? A valve acts like a door that only opens in one direction. If the door is held by someone at a fixed point, only the arm moves as the door opens and closes. When the door is closed the arm is fully extended, so the door can only be opened in one direction.

32 © Boardworks Ltd of 49 How do valves work? A valve acts like a door that only opens in one direction. In the heart, the tendons holding the valve are like the arm holding the door. One end of each tendon is fixed to the wall of the heart and so the valve can only open in one direction.

33 © Boardworks Ltd of 49 The Heart and Circulatory System The circulatory system Structure of the heart How the heart pumps blood Valves in the heart Summary quiz Contents

34 © Boardworks Ltd of 49 How does the heart pump blood ? Imagine the force needed to squeeze a tennis ball. Thats how much force the heart uses to pump blood around the body! How does the heart produce enough force to keep doing this 24 hours a day? The heart can pump blood because it is made of muscle. Muscle tissue works by contracting (squeezing) and relaxing.

35 © Boardworks Ltd of 49 How does the heart pump blood ? All the parts of the heart on either side, work together in a repeated sequence. The two atria contract and relax; then the two ventricles contract and relax. This is how blood moves through the heart and is pumped to the lungs and the body. One complete sequence of contraction and relaxation is called a heartbeat.

36 © Boardworks Ltd of 49 Heartbeat animation

37 © Boardworks Ltd of 49 Stages of a heartbeat Stage 1: A heartbeat begins with the heart muscle relaxed and valves closed. Blood flows into the two atria and both sides fill up with blood. This blood has to be pushed through the valves to get into the ventricles. How does this happen?

38 © Boardworks Ltd of 49 Stages of a heartbeat Stage 2: The atria contract and the blood is squeezed which causes the valves leading to the ventricles to open. Blood then flows from the atria into the ventricles. What happens to the open valves when the atria are empty?

39 © Boardworks Ltd of 49 Stages of a heartbeat Stage 2 (continued): The valves between the atria and the ventricles close. This prevents any backflow. What happens next to the blood in the ventricles?

40 © Boardworks Ltd of 49 Stages of a heartbeat Stage 3: Almost immediately, the ventricles contract and the blood is squeezed again. The pressure of the blood forces open the valves leading out of the heart. Blood is pumped out of the heart. What happens to the open valves when the ventricles are empty?

41 © Boardworks Ltd of 49 Stages of a heartbeat Stage 3 (continued): When the ventricles are empty, the valves leading out of the heart close and the heart muscle relaxes. This completes the sequence of contraction and relaxation in one heartbeat. What will happen next?

42 © Boardworks Ltd of 49 Stages of a heartbeat Stage 1 (again): The atria fill up with blood as the heartbeat sequence begins again. Why are the walls of the atria thinner than the walls of the ventricles? Why is the wall of the left ventricle thicker than the right ventricle?

43 © Boardworks Ltd of 49 What does a doctor hear when they listen to a patients heart? Listening to a beating heart: lub-dub The lub is caused by the closing of the valves leading to the ventricles. The dub is caused by the closing of the valves leading out of the heart. lub-dub, The sound of a heartbeat is the sound of the heart valves. lub-dub, lub-dub…

44 © Boardworks Ltd of 49 Measuring a beating heart You can measure how fast your heart is beating by taking your pulse. Each pulse that you feel is due to the pressure of blood leaving the heart as the left ventricle contracts. Place the fingertips of one hand on the opposite wrist, where an artery passes near the surface of the skin. What is your heart rate, in beats per minute, right now?

45 © Boardworks Ltd of 49 …in one hour? …in one day? …in one year? …in 70 years? How many heartbeats ? If your heart beats at an average rate of 70 times per minute, how many heartbeats are there… 70 x 60 = 4, 200 x 24 = 100, 800 x 365 = 36, 792, 000 x 70 = 100, , 792, 000 2, 575, 440, 000 4, 200

46 © Boardworks Ltd of 49 The sequence of a heartbeat

47 © Boardworks Ltd of 49 Journey of blood around the body

48 © Boardworks Ltd of 49 The Heart and Circulatory System The circulatory system Structure of the heart How the heart pumps blood Valves in the heart Summary quiz Contents

49 © Boardworks Ltd of 49 Multiple-choice quiz


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