Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
The respiratory system 1 of 28 © Boardworks Ltd 2006 The respiratory system 2 of 28 © Boardworks Ltd 2006 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. 3 of 28 © Boardworks Ltd 2006 Mechanisms of breathing – inspiration When you breathe in: intercostal muscles between the ribs contract, pulling the chest walls up and out Intercostal muscles pull ribs 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. 4 of 28 Diaphragm contracts and moves down © Boardworks Ltd 2006 Mechanisms of breathing – inspiration 5 of 28 © Boardworks Ltd 2006 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. Diaphragm relaxes and bulges up 6 of 28 The lungs decrease in size, so the pressure inside increases and air is pushed up the trachea and out through the nose or mouth. © Boardworks Ltd 2006 Mechanisms of breathing – expiration 7 of 28 © Boardworks Ltd 2006 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. 8 of 28 © Boardworks Ltd 2006 Gas exchange at the alveoli 9 of 28 © Boardworks Ltd 2006 Composition of inhaled and exhaled air Gas Oxygen Carbon dioxide Nitrogen Water vapour Amount in inhaled air Amount in exhaled air 21% 17% Very small amount 3% 79% 79% Small amount Large amount What are the main differences between inhaled and exhaled air? Why does mouth-to-mouth resuscitation work? 10 of 28 © Boardworks Ltd 2006 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 11 of 28 © Boardworks Ltd 2006 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. 12 of 28 © Boardworks Ltd 2006 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. 13 of 28 © Boardworks Ltd 2006 Breathing changes during exercise Look at these statistics for a 16 year-old athlete: During rest Respiratory rate Volume per breath Minute volume During exercise 14 breaths/ minute 32 breaths/ minute 0.4 litres 2.4 litres ? ? Calculate the athlete’s minute volumes during rest and exercise. Rest minute volume = 5.6 litres Exercise minute volume = 76.8 litres 14 of 28 © Boardworks Ltd 2006 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. 15 of 28 © Boardworks Ltd 2006 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. respiration energy glucose oxygen Waste products, including carbon dioxide, are produced as a result of the chemical reactions. These must be removed and excreted. 16 of 28 © Boardworks Ltd 2006 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. 17 of 28 © Boardworks Ltd 2006 Aerobic respiration 18 of 28 © Boardworks Ltd 2006