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Mechanisms of breathing 1 Mechanisms of breathing.

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Presentation on theme: "Mechanisms of breathing 1 Mechanisms of breathing."— Presentation transcript:

1 Mechanisms of breathing 1 Mechanisms of breathing

2 What you will learn about in this topic: 1.The function of the respiratory system 2.The mechanisms of breathing 3.The role of the lungs 4.Alveoli 5.Composition of air inhaled and exhaled Mechanisms of breathing 2

3 Mechanisms of breathing 3 Learning objectives By the end of this presentation you should be able to: Understand the function of the respiratory system Describe the effects of exercise on breathing Explain what happens when you breathe

4 The function of the respiratory system The function of the respiratory system is to get oxygen into the body and carbon dioxide and waste products from metabolism out of the body. Mechanisms of breathing 4

5 This happens through the act of breathing. Breathing in (inhalation) gets the oxygen in, so it can be used by the body to release energy. Breathing out (exhalation) removes the carbon dioxide so it does not build up and poison the body. Mechanisms of breathing 5

6 The following are all parts of the respiratory system: Air passages Lungs Diaphragm Mechanisms of breathing 6

7 Composition of inspired and expired air The air we breathe in is very different from the air we breathe out. The parts that make up inhaled and exhaled air are called its composition. Mechanisms of breathing 10

8 Percentage of air inhaled: Key ■ Nitrogen ■ Oxygen ■ Carbon dioxide ■ Other Mechanisms of breathing 11

9 Percentage of air exhaled: Key ■ Nitrogen ■ Oxygen ■ Carbon dioxide ■ Other Mechanisms of breathing 12

10 The link between respiration and circulation Oxygen goes from the respiratory system to the circulatory system and then back to the respiratory system. Mechanisms of breathing 13

11 Oxygen breathed in goes through the mouth or nose, down the trachea, into the lungs and into the alveoli. Mechanisms of breathing 14

12 Oxygen then passes through the alveoli walls into the red blood cells, via the capillaries. Oxygen joins with haemoglobin to make oxyhaemoglobin. The oxyhaemoglobin is used by the working body and is transported by the circulatory system to cells needing to release energy. Mechanisms of breathing 15

13 Carbon dioxide is produced as a waste product. This is converted into a gas and passes back through the alveoli walls, via the capillaries into the blood plasma. The carbon dioxide passes through the capillary and alveoli walls into the alveoli. It is then exhaled from the body. Mechanisms of breathing 16

14 Parts of the respiratory system Mechanisms of breathing 17

15 Expiration The mechanism of breathing Lungs are not muscle, cannot move of their own accord and are not controlled by the central nervous system. The key to breathing is the diaphragm and the intercostal muscles between the ribs. Mechanisms of breathing 18

16 When we breathe in (inspiration) the following happens: Mechanisms of breathing 19 The diaphragm pulls down The intercostal muscles contract Air pressure is reduced Air is sucked through the tubes into the lungs The chest expands.

17 Mechanisms of breathing 20

18 When we breathe out (expiration) the opposite happens: Mechanisms of breathing 21 The diaphragm relaxes into its dome position The intercostal muscles relax The chest becomes smaller Pressure increases in the lungs Air is forced out

19 Mechanisms of breathing 22

20 Task 1 In groups of four, write 13 statements on 13 pieces of card (one on each card) about the route of oxygen and carbon dioxide around the body. Put your cards in order, starting and ending with a card marked ‘Oxygen is inhaled’. Mechanisms of breathing 23

21 Possible answers to Task 1 Oxygen passes through the larynx and trachea. Oxygen arrives in the lungs via the bronchi and bronchioles. Oxygen passes to the alveoli and transfers to the haemoglobin through the plural membrane Mechanisms of breathing 24

22 The haemoglobin in the red blood cells binds with the oxygen to become oxyhaemoglobin. The blood travels through the pulmonary vein to the left side of the heart. The heart pumps the blood through the aorta to the arteries. The arteries carry the oxygenated blood around the body. Mechanisms of breathing 25

23 The haemoglobin releases the oxygen at the muscles and collects the carbon dioxide; the blood is now considered deoxygenated. The veins carry the deoxygenated blood. The deoxygenated blood arrives at the heart. Mechanisms of breathing 26

24 The heart pumps the deoxygenated blood back to the lungs via the pulmonary artery. The carbon dioxide passes across the pleural membrane and into the alveoli. The carbon dioxide passes through the trachea and is exhaled. Mechanisms of breathing 27

25 The role of the lungs Mechanisms of breathing 28 The lungs are positioned inside the chest cavity and are protected by the ribcage.

26 The action of breathing means that the lungs are constantly moving in and out. To protect them from any friction due to the movement, the pleural membrane forms a complete lining around them. The pleural membrane is smooth and has a moist, slimy mucus. Mechanisms of breathing 29

27 Alveoli Mechanisms of breathing 30 Alveoli are tiny air sacs at the end of the bronchioles.

28 There are millions of them that allow gases to exchange inside them. Oxygen passes across the pleural membrane and into the blood. Carbon dioxide passes from blood to the alveoli. Mechanisms of breathing 31

29 Here is a simplified version of what happens: Mechanisms of breathing 32 Oxygen from the air breathed in enters the circulatory system to be used by the working muscles.

30 Carbon dioxide, which is toxic to the system, transfers from the used blood, out of the circulatory system, back into the alveoli, to be breathed out along with oxygen, water and nitrogen. Mechanisms of breathing 33

31 The capillaries, covering the surface of the alveoli, link the respiratory system with the circulatory system. Mechanisms of breathing 34 Regular exercise conditions the lungs to excrete more of the carbon dioxide from the body.

32 Tidal volume is the amount of air breathed in and out of the body during normal breathing. During exercise, the volume is forced to change. It is then called forced breathing. Mechanisms of breathing 35

33 Vital capacity is the largest amount or volume of air that can be exhaled after the largest possible inhalation. Residual volume is the amount of air that, even after as much air as possible has been exhaled, is left in the lungs. Mechanisms of breathing 36

34 Task 2 In groups of four, describe the action of breathing using the following words to help you: Mechanisms of breathing 37 Nose Mouth Trachea Lungs Ribs Intercostal muscles Diaphragm

35 Mechanisms of breathing 38 Possible answers to Task 2 From the nose or mouth, air enters the trachea and moves towards the lungs. The trachea divides into two branches called the bronchi. These sub-divide into smaller tubes called bronchioles. During heavy exercise the body uses the intercostal muscles between the ribs to aid the diaphragm in the exhalation of air from the lungs. At the end of the bronchioles are alveoli. Alveoli are air sacs with many tiny blood vessels called capillaries running from them.

36 Exam questions 1. Explain the process of inspiration. 2. Explain the process of expiration. Mechanisms of breathing 39

37 Mechanisms of breathing 40 What you have learnt about in this topic: 1.The function of the respiratory system 2.The mechanisms of breathing 3.The role of the lungs 4.Alveoli 5.Composition of air inhaled and exhaled

38 Mechanisms of breathing 41 Learning objectives You should now be able to: Understand the function of the respiratory system Describe the effects of exercise on breathing Explain what happens when you breathe


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