GCSE Physical Education

1. GCSE Physical Education Aerobic and Anaerobic Respiration and the Respiratory System

2. The respiratory system

3. The respiratory system

4. 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.

5. Mechanisms of breathing – inspiration When you breathe in: Intercostal muscles pull ribs up and out • 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

6. Mechanisms of breathing – inspiration

7. Mechanisms of breathing – expiration When you breathe out: Ribs move in and down • 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. Diaphragm relaxes and bulges up

8. Mechanisms of breathing – expiration

9. You do not need to remember this Measuring breathing 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.

10. You do not need to remember this Measuring breathing

11. You do not need to remember this Measuring breathing

12. You do not need to remember this 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 = 14 × 0.5 litres = 7.0 litres

13. 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.

14. Gas exchange at the alveoli

15. Composition of inhaled and exhaled air 21% Very small amount 79% Small amount 17% 3% 79% Large amount What are the main differences between inhaled and exhaled air? Why does mouth-to-mouth resuscitation work?

16. Breathing during exercise During exercise the muscle cellsuse 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.

17. Breathing during exercise Muscle cell respiration increases – more oxygen is used up and levels of CO2 rise. The brain detects increasing levels of CO2 – 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. The brain also tells the heart to beat faster so that more blood is pumped to the lungs for gaseous exchange. More oxygenated blood gets to the muscles and more CO2 is removed.

18. You do not need to remember this Breathing changes during exercise Look at these statistics for a 16 year-old athlete: Calculate the athlete’s minute volumes during rest and exercise. Rest minute volume = 5.6 litres Exercise minute volume = 76.8 litres

19. respiration glucose oxygen 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. energy Waste products, including carbon dioxide, are produced as a result of the chemical reactions. These must be removed and excreted.

20. 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. carbon dioxide glucose + oxygen energy + + water 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.

21. Aerobic respiration

22. 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.

23. 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 CO2 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.

24. Anaerobic exercise

25. 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.

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

27. Can you remember all these keywords? • Larynx • Trachea • Bronchus / Bronchi • Bronchioles • Alveoli • Diaphragm • Intercostal muscles • Oxygen uptake • Respiratory rate • Aerobic respiration • Anaerobic respiration • Oxygen debt • Lactic acid