KS4 Physical Education

Transcription

1 KS4 Physical Education The Respiratory System These icons indicate that teacher s notes or useful web addresses are available in the Notes Page. This icon indicates that the slide contains activities created in Flash. These activities are not editable. 1 of 28 For more detailed instructions, see the Getting Started presentation.

2 Learning objectives Learning objectives 2 of 28 What we will learn in this presentation: The structures of the respiratory system and their functions The mechanisms of breathing How gases are exchanged during breathing The composition of inhaled and exhaled air The different measurements of lung capacity and breathing The effects of exercise on the respiratory system What is meant by aerobic and anaerobic respiration The oxygen debt.

3 The respiratory system 3 of 28

4 The respiratory system 4 of 28

5 5 of 28 The nasal passages and lungs Air is drawn into the body via the nose or mouth. There are advantages to breathing through your nose: the air is warmed so that it is closer to body temperature tiny hairs and mucus in the nose filter the air, preventing larger dust and pollen particles reaching the alveoli mucus moistens the air, making it easier for the alveoli to absorb. Air then travels through the larynx, trachea (windpipe), bronchi (one bronchus to each lung) and bronchioles to the alveoli, where oxygen passes into the bloodstream.

6 6 of 28 Mechanisms of breathing inspiration When you breathe in: intercostal muscles between the ribs contract, pulling the chest walls up and out the diaphragm muscle below the lungs contracts and flattens, increasing the size of the chest the lungs increase in size, so the pressure inside them falls. This causes air to rush in through the nose or mouth. Diaphragm contracts and moves down Intercostal muscles pull ribs up and out

7 Mechanisms of breathing inspiration 7 of 28

8 8 of 28 Mechanisms of breathing expiration Ribs move in and down Diaphragm relaxes and bulges up When you breathe out: Intercostal muscles between the ribs relax so that the chest walls move in and down. The diaphragm muscle below the lungs relaxes and bulges up, reducing the size of the chest. The lungs decrease in size, so the pressure inside increases and air is pushed up the trachea and out through the nose or mouth.

9 Mechanisms of breathing expiration 9 of 28

10 10 of 28 Gas exchange at the alveoli The alveoli are bunches of tiny air sacks inside the lungs. Each individual sack is called an alveolus. When you breathe in, they fill with air. The alveoli are covered in tiny capillaries (blood vessels). Gases can pass through the thin walls of each alveolus and capillary, and into the blood stream. Gases can also pass from the blood stream, into the alveolus.

11 Gas exchange at the alveoli 11 of 28

12 Composition of inhaled and exhaled air 12 of 28 Gas Oxygen Carbon dioxide Nitrogen Water vapour Amount in inhaled air 21% Very small amount 79% Small amount Amount in exhaled air 17% 3% 79% Large amount What are the main differences between inhaled and exhaled air? Why does mouth-to-mouth resuscitation work?

13 Measuring breathing 13 of 28 Tidal volume is the amount you breathe in and out in one normal breath. Respiratory rate is how many breaths you take per minute. Minute volume is the volume of air you breathe in one minute. Vital capacity is the maximum volume of air you can breathe out after breathing in as much as you can. Residual volume is the amount of air left in your lungs after you have breathed out as hard as you can.

14 Measuring breathing 14 of 28

15 Measuring breathing 15 of 28

16 Calculating minute volume Remember: Minute volume is the volume of air you breathe in one minute. You can calculate a person s minute volume by multiplying the volume of air they breathe in one breath, by their respiratory (breathing) rate. Question If you breathe 14 times in one minute (respiratory rate) and you breathe 0.5 litres in each breath, what is your minute volume? Answer: Minute volume = litres = 7.0 litres 16 of 28

17 17 of 28 Breathing during exercise During exercise the muscle cells use up more oxygen and produce increased amounts of carbon dioxide. Your lungs and heart have to work harder to supply the extra oxygen and remove the carbon dioxide. Your breathing rate increases and you breathe more deeply. Heart rate also increases in order to transport the oxygenated blood to the muscles.

18 Breathing during exercise 18 of 28 Muscle cell respiration increases more oxygen is used up and levels of CO 2 rise. The brain detects increasing levels of CO 2 a signal is sent to the lungs to increase breathing. Breathing rate and the volume of air in each breath increase. This means that more gaseous exchange takes place. More oxygenated blood gets to the muscles and more CO 2 is removed. The brain also tells the heart to beat faster so that more blood is pumped to the lungs for gaseous exchange.

19 Breathing changes during exercise 19 of 28 Look at these statistics for a 16 year-old athlete: During rest During exercise Respiratory rate 14 breaths/ minute 32 breaths/ minute Volume per breath 0.4 litres 2.4 litres Minute volume?? Calculate the athlete s minute volumes during rest and exercise. Rest minute volume = 5.6 litres Exercise minute volume = 76.8 litres

20 20 of 28 The effects of exercise on lung structures In the long-term, regular exercise strengthens the respiratory system. The respiratory muscles (the diaphragm and intercostals) get stronger, so they can make the chest cavity larger. This larger chest cavity means more air can be inspired, therefore increasing your vital capacity. More capillaries form around the alveoli, so more gaseous exchange can take place. Gas exchange can now take place more quickly meaning exercise can be maintained at a higher intensity for longer.

21 21 of 28 Respiration Respiration is the process that takes place in living cells which releases energy from food molecules. Glucose from food is used to fuel exercise. Oxygen is required to break down the glucose to produce energy. This energy is used to make muscles contract. glucose Waste products, including carbon dioxide, oxygen are produced as a result of the chemical reactions. These must be removed and excreted. respiration energy

22 22 of 28 Aerobic respiration There are two different types of respiration. When you exercise at a steady, comfortable rate, the cardiovascular system is able to supply the muscles with all the oxygen they need. Under these conditions, aerobic respiration takes place. glucose + oxygen energy carbon + + water dioxide Aerobic exercise can be maintained for long periods without the performer getting breathless or suffering muscle cramps. Moderate activities like walking, jogging, cycling and swimming use aerobic respiration.

23 Aerobic respiration 23 of 28

24 24 of 28 Anaerobic respiration When you exercise at a high intensity, the cardiovascular system cannot supply enough oxygen to the muscles. Under these conditions, anaerobic respiration takes place. glucose energy + lactic acid With no oxygen available, glucose is burned to produce energy and lactic acid. Lactic acid is a mild poison. As it builds up, it causes muscle pain and eventually cramp. Short, intense activities like sprinting, weightlifting, jumping and throwing use anaerobic respiration.

25 25 of 28 Oxygen debt After anaerobic activity, oxygen is needed to neutralize the lactic acid. This is called an oxygen debt. It is repaid after exercise. The oxygen reacts with the lactic acid to form CO 2 and water. Rapid and deep breathing is needed for a short period after high intensity exercise in order to repay the debt. This also helps to remove the carbon dioxide which accumulates in the blood during intense exercise.

26 Anaerobic exercise 26 of 28

27 Exam-style questions 27 of Describe the passage of oxygen from the nasal passages to the bloodstream. 2. David goes jogging once a week for 45 minutes. a) List two differences between the air that David inhales and the air that he exhales while jogging. b) What two substances are used by David s body cells to produce energy? What are the products of this reaction? David tries to increase his pace. He finds that he is forced to stop running and breathe hard for several minutes. c) Explain why David had to stop. d) How did breathing hard help him to recover?

28 Can you remember all these keywords? 28 of 28 Larynx Trachea Bronchus / Bronchi Bronchioles Alveoli Diaphragm Intercostal muscles Oxygen uptake Tidal volume Respiratory rate Minute volume Vital capacity Residual volume Aerobic respiration Anaerobic respiration Oxygen debt Lactic acid