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Learning objectives Learning objectives

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Presentation on theme: "Learning objectives Learning objectives"— Presentation transcript:

1 Learning objectives Learning objectives
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. Learning objectives 1 of 28 © Boardworks Ltd 2006

2 The respiratory system

3 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.

4 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

5 Mechanisms of breathing – inspiration

6 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

7 Mechanisms of breathing – expiration

8 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.

9 Gas exchange at the alveoli

10 Composition of inhaled and exhaled air
Gas Amount in inhaled air Amount in exhaled air Oxygen Carbon dioxide Nitrogen Water vapour 21% Very small amount 79% Small amount 17% 3% 79% Large amount What are the main differences between inhaled and exhaled air? Ask the students to compare the relative amounts. Point out that: The amount of oxygen inhaled is greater than the amount of oxygen exhaled. Consider the efficiency of respiration at the cells. The amount of carbon dioxide is greater in exhaled air. The amount of nitrogen is the same. Mouth to mouth resuscitation works because there is still a lot oxygen left in exhaled air. Why does mouth-to-mouth resuscitation work?

11 Respiratory rate is how many breaths you take per minute.
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. Clarify and expand on the definitions with the students Residual volume is the amount of air left in your lungs after you have breathed out as hard as you can.

12 Measuring breathing

13 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? Get students to calculate the answer before revealing it. Point out that at rest, the volume of air breathed in each breath will be the person’s tidal volume. During extreme exercise, it may be closer to their vital capacity. Answer: Minute volume = 14 × 0.5 litres = 7.0 litres

14 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.

15 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. Relate these facts to improvements in performance. Emphasise that lungs are NOT muscles and therefore do not increase in size – they function more efficiently. Gas exchange can now take place more quickly meaning exercise can be maintained at a higher intensity for longer.

16 Key Terms The role of the blood
As well as controlling body temperature, one of the basic roles of the blood is as a transporter and it is through this function that the oxygen, glucose and waste products are all transported around the body. Key Terms Glycogen: the main form of carbohydrate storage, which is converted into glucose as needed by the body to satisfy its energy needs Lactic Acid: a mild poison and waste product of anaerobic respiration Gaseous Exchange: the process where oxygen is taken in from the air and exchanged for carbon dioxide.

17 Make sure you understand the process of gaseous exchange and that aerobic respiration is with oxygen. Knowing activities that require aerobic respiration is also vital It is crucial that you are able to identify the difference between aerobic and anaerobic exercise and respiration. You should be able to give good examples of activities for both

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