1.2 – The structure and function of the respiratory system Learning objectives To understand the structures of the respiratory system and their functions. To be able to describe the mechanisms of breathing To learn the composition of inhaled and exhaled air To be able to describe how gases are exchanged during breathing. To understand the different measurements of lung capacity and breathing.

Respiratory System Watch me This involves the LUNGS and works closely with the cardiovascular system. Watch me What is the key function of the respiratory system?

Inhaled and exhaled air On average a person breathes 15 times a minute. The table shows the composition of air. Gas Amount in inhaled air Amount in exhaled air Oxygen 20 16 Carbon dioxide Trace 4 Nitrogen 79 Water vapour Small amount Large amount

Breathing Volumes Tidal volume: This is the amount you breathe in and out in one normal breath. Vital capacity: This is the maximum volume of air you can breathe out after breathing in as much as you can. (peak flow) Look at the two tidal volume readings below. What changes have taken place and why? Name Tidal volume at rest (ml) Tidal volume during exercise (ml) James 500 3500

How exercise effects breathing Name Tidal volume at rest (ml) Tidal volume during exercise (ml) James 500 3500 Exercise causes an increase in breathing rate and depth of breathing. This is due to a greater need for oxygen in the body and removal of carbon dioxide. Tidal volume can increase up to 5-9 times higher than at rest to cope with exercise demands. As we become fitter, the body’s Vital Capacity will increase as will blood carrying capacity. These adaptations will contribute to better performance.

Vital Capacity Measurements is the maximum volume of air you can breathe out after breathing in as much as you can. (peak flow) What is your peak flow measurement? Best score ______ What factors will effect your peak flow score? Photo: © Stock.xchng.

Peak flow values/averages BOYS Standard Measurement Very Poor 300 Poor 400 Average 500 Good 600 Very Good/Excellent 700 GIRLS Standard Measurement Very Poor 250 Poor 350 Average 450 Good 550 Very Good/Excellent 650

Components of the respiratory system Bronchi Trachea Bronchioles Lungs Diaphragm Alveoli Photo by: © deshow.net

Gaseous exchange at the alveoli Gaseous exchange takes places at the alveoli. The alveoli are tiny air sacks inside the lungs. When you breathe in, they fill with air. The alveoli are covered in tiny capillaries (blood vessels). Gases can pass through the thin walls and travel into the blood stream. With training this process of gaseous exchange becomes more efficient and therefore improves performance. Photo by: © LOCOG

Inspiration and Expiration During inspiration how does air enter the lungs? Photo by: © LOCOG

The mechanism of breathing Breathing is the first stage in supplying oxygen to our body cells. When breathing in (inspiration): The intercostal muscles contract, lifting the ribs upwards and outwards causing the to chest expand. The diaphragm contracts. It pulls down and flattens out the floor of the rib cage. The lungs increase in size as the chest expands. The pressure inside our lungs falls as they expand. The higher pressure of air outside means air is now sucked into the lungs through the nose and mouth.

The mechanism of breathing When breathing out (expiration): The intercostal muscles relax. The ribs move downwards and inwards under their own weight. The cheat gets smaller. The diaphragm relaxes. It is pushed back into a domed position by the organs underneath it. The lungs decrease in size as the chest gets smaller. They are squeezed by the ribs and diaphragm. The pressure inside the lungs increases as they get smaller. The air pressure outside is now lower than in our lungs. Air is forced out of the lungs through the nose and mouth.

Cardiovascular and respiratory System Responses by the respiratory and cardiovascular system do not work in isolation. The demands of exercise cause changes in both systems and one cannot work without the other. Photo by: deshow.net Photo by: LOCOG i.e. Increases in tidal volume means more oxygen is inhaled and can only benefit the body if heart rate increases too to pump to working muscles.

Interpreting data and graphs Figure 1 below shows a comparison of Emily’s exhaled air both at rest and during exercise Rest During Exercise What do you notice about the difference between the 2 pie charts? What is the reason for this?

Apply it! Explain the terms below: What has stuck with you? Cardio-Respiratory system Explain the terms below: - Tidal volume - Alveoli - Expiration Describe the process of inspiration? Explain the route of oxygen from the trachea to the muscles. Complete the table below? Gas Amount in inhaled air Amount in exhaled air Oxygen Carbon dioxide Nitrogen Water vapour

Practice it! Exam questions 1. (i) Which of the following statements describes the movement of the ribs and diaphragm during expiration? (1) A The ribs move up and out and the diaphragm moves down. B The ribs move up and out and the diaphragm moves up. C The ribs move down and in and the diaphragm relaxes. D The ribs move down and in and the diaphragm contracts.   (ii) Which of the following statements describes the correct passage of air into the lungs? (1) A Nasal passages, trachea, bronchioles, alveoli B Trachea, bronchioles, bronchi, alveoli C Larynx, bronchi, bronchioles, ribs D Larynx, bronchi, bronchioles, alveoli

Practice it! Exam questions (iii) The following statements all relate to the relative composition of air. Which of the statements is referring to the typical composition of oxygen and carbon dioxide in exhaled air? (1)   A oxygen 21%, carbon dioxide 0.04% B oxygen 16%, carbon dioxide 0.04% C oxygen 16%, carbon dioxide 4% D oxygen 21%, carbon dioxide 4%

Practice it! Exam questions 2. Figure 8 is a diagram of the respiratory system. (a) Give the anatomical names of the parts labelled A, B and C. A ................................................. B ................................................. C ................................................. (3) (b) (i) In order to get oxygen into the lungs the player breathes in. Describe the movement of the ribs and diaphragm during inspiration. (2) Ribs ...................................... Diaphragm ........................... (ii) Why do the ribs and diaphragm move in this way? (1) ...................................................................................................................................................................................................................................................................................................................................................................................

Practice it! Exam questions 3. The composition of inspired air differs from expired air. Complete the table below by adding the values for expired air (2) Gas % in inspired air % in expired air Oxygen 21 Carbon Dioxide 0.03

Practice it! Marks Scheme: i) C ii) A iii) C 2. a) A– Trachea, B – Bronchiole, C – Alveoli/ Alveolus. b) i) Ribs – move up and out. Diaphragm – contracts/flattens/moves down. ii) Make more room for more air/cause pressure difference to cause air to move in. 3. 16% / 4%