KS4 Biology

1. The Heart and Circulatory System KS4 Biology

2. Contents The heart and circulatory system How are substances transported? The heart: structure and function The valves: structure and function The action in motion Multiple choice section

3. How are substances transported in our bodies? The next organ system we will be considering can be known by two names….. Blood system Circulatory system The circulatory system is made of two parts: 1. The heart 2. The blood vessels

4. What we use in the air One of the substances that the circulatory system transports are respiratory gases. For example, the oxygen that the body needs, must be taken to the cells and the carbon dioxidewaste gas must be taken away from the cells.

5. Dissolved gases in blood blood high in oxygen blood low in oxygen oxygenated deoxygenated As these gases are carried by the blood, it means that in terms of the presence of gas, we have two types of blood. At all times these two types of blood cannot mix. Why do you think this is?

6. A double circulatory system Lungs Body cells Because of this our circulatory system is in two parts. It is in fact called a double circulatory system. This section of the system including the left side of the heart, deals with the oxygenated blood. This section of the system including the right side of the heart, deals with the deoxygenated blood.

7. The human circulatory system

8. Contents The heart and circulatory system How are substances transported? The heart: structure and function The valves: structure and function The action in motion Multiple choice section

9. The heart: structure and function The Heart In this unit we are going to focus on the heart.. This is the pump at the centre of the circulatory system. Not all living organisms have hearts. Also, the shape of the heart can change, depending on what species you look at.

10. One big muscle • The heart is made almost entirely of muscle. It is unlike any other muscle in your body because it never tires. And even though it is full of blood it still needs it own blood supply. • Oxygenated blood is carried to the heart by the coronary arteries. • Each side of the heart has two chambers. • An top chamber or atrium and • A bottom chamber or ventricle Each of these chambers has its own function. Look at the diagram on the next slide to see what that is.

11. Diagrammatical representation

12. Contents The heart and circulatory system How are substances transported? The heart: structure and function The valves: structure and function The action in motion Multiple choice section

13. The valves: structure and function Besides the chambers there is also another very important part of the heart – the valves. These valves are found between the top and bottom chambers on both sides of the heart. blood These valves are rather like doors that only open in one direction. valve

14. Valves in action As the atrium fills with blood, the valves are closed. When the atrium contracts and squeeze the blood, the valves are pushed open. These valves are connected to the side wall of the heart by tough tendons. These tendons allow the valves to close but not invert.

15. Tendon holding a valve valve tendon wall of ventricle These tendons can be compared to an arm holding onto the handle of a door.

16. Analogy of a valve The arm bends as the door is opened. When the door is closed the arm is fully extended. It would be impossible for the door to open in the other direction without the person moving with it. The tendon (represented by the arm) is held in a fixed position and therefore the valve (door) can only open in one direction.

17. Preventing backflow However, the valves remain firmly shut. The blood will naturally push against the valve. In this way, the blood can be moved from chamber to chamber quite efficiently. The valves prevent the blood from moving in the wrong direction.

18. More valves we also find valves here ...and here! These extra valves stop the blood from re-entering the heart when it is pumped from the ventricles.

19. Lub - dub artery ventricle valve When the blood knocks against the first heart valves, it makes a ‘lub’ like sound. When the blood knocks against the second set of heart valves, it makes a ‘dub’ like sound. The blood ‘slaps’ against the valve and then passes along the artery. These two sounds – lub and dub – are actually what we hear as our heartbeat. So our heartbeat is in fact the sound of the valves opening and closing.

20. The heart’s main valves

21. Contents The heart and circulatory system How are substances transported? The heart: structure and function The valves: structure and function The action in motion Multiple choice section

22. The action in motion Now that we can name all of the parts of the heart it is time to see how they work to push blood around the body. The heart pumps blood when its muscle contracts. As the muscle contracts the chamber gets smaller and squeeze the blood out. The two sides of the heart work together. The atria contract and relax at the same time, as do the ventricles. The next two slides describe what occurs inside the heart during one heart cycle.

23. The action in motion blood from the lungs blood from the body 1. The heart beat begins when the heart muscles relax and blood flows into the atria. • The atria then contract and the valves open to allow blood into the ventricles.

24. The action in motion • The ventricles contract forcing the blood to leave the heart. At the same time, the atria are relaxing and once again filling with blood. The staged cycle then repeats itself.

25. Left and right ventricles Do you notice anything different about the two sides of the heart? Well, the left ventricle wall is clearly thicker than the right ventricle wall. Why is this? To answer this question, think about where the blood is going when it leaves the right and left ventricles.

26. Different destinations This journey is far less demanding. The right ventricle only has to pump blood from the heart to the adjacent lungs. This journey is enormous. The left ventricle has to pump blood all over the body! lungs body cells Therefore, the left ventricle needs a thicker wall to generate a stronger ‘squeeze’ on the blood.

27. Drag the labels to the correct numbered boxes on the diagram of the blood system.

28. Traffic control

29. Label the heart

30. Answer the questions

31. Oxygenated or deoxygenated?

32. Getting things in order

33. Controlled circulation

34. Contents The heart and circulatory system How are substances transported? The heart: structure and function The valves: structure and function The action in motion Multiple choice section

35. Multiple choice section Multiple choice questions

36. Q1 What is the alternative name for the blood system? A the heart system B the circulatory system C the transporting system D the pumping system

37. A heart, lungs, brain and bladder B arteries, heart and stomach C arteries, veins and heart D heart, veins and pancreas Q2 Which of the following organs are found in the blood system?

38. A transport substances, such as oxygen and dissolved nutrients, around the body. B support the movement of the body. C digest large molecules of food. D carry chemical messages between the brain and the nerves. Q3 The function of the circulatory system is to...

39. A fat tissue B skin tissue C nerve tissue D muscle tissue Q4 What is the wall of the heart mainly made from?

40. A The blood carries two vital materials. B There are actually two parts to the heart. C The system is divided into two separate circuits. D The blood flows in two directions. Q5 The blood system is often known as the “double circulation” system. Why is this?

41. A four B it varies from human to human C two D none of the above Q6 How many chambers are there in the human heart?

42. Name the chamber that is labelled W (be careful!). A the right ventricle B the left ventricle C the right atrium D the left ventricle Q7 W X Y Z Look at the diagram below.

43. A It would leave the heart. B It would pass into chamber Z. C It would pass across into chamber W. D It would flow into all the other chambers. Q8 W X Y Z If blood entered the chamber X, where would it then go?

44. A W B X C Y D Z Q9 W X Y Z Which chamber is the left ventricle?

45. A the left B the right C both sides are the same thickness D middle is thicker Q10 W X Y Z Which side of the heart has the thickest wall?

46. A the right and left atrium B the right and left ventricle C the right atrium and the left ventricle D the right ventricle and the left atrium Q11 Into which chambers does blood enter the heart?

47. Athe right and left atrium B the right and left ventricle C the right atrium and the left ventricle D the right ventricle and the left atrium Q12 Through which two chambers does blood leave the heart?

48. A Heart - Lungs - Body - Lungs B Heart - Body - Heart - Body - Lungs C Body - Lungs - Heart - Body - Heart D Heart - Lungs - Heart - Body Q13 Which of these combinations lists the two circuits that blood makes through the body?

49. Know what’s in your heart P S R Q T U Look at the diagram below.

50. A an atrium B a ventricle C a capillary D a chamber Part 1 P S R Q T U What is part T?