Inhalation

Exhalation

Ventilation. Put the following into columns and in the right order to describe inhalation (inspiration) and exhalation (expiration). Diaphragm contracts to become flatter and pushes digestive organs down. Diaphragm relaxes and is pushed up by displaced organs underneath External intercostal muscles contract to raise the ribs Volume of chest cavity increases Air moves out of the lungs External intercostal muscles relax and ribs fall Pressure in chest cavity drops below atmospheric pressure Air moves into the lungs Volume of chest cavity decreases Pressure in lungs increases and rises above atmospheric pressure

Answers Inhalation Exhalation External intercostal muscles contract to raise the ribs Diaphragm contracts to become flatter and pushes digestive organs down. Volume of chest cavity increases Pressure in chest cavity drops below atmospheric pressure Air moves into the lungs Exhalation External intercostal muscles relax and ribs fall Diaphragm relaxes and is pushed up by displaced organs underneath Volume of chest cavity decreases Pressure in lungs increases and rises above atmospheric pressure Air moves out of the lungs Interactive Iron Lung

Calculate your breathing rate Count how many times you breath in and out in one minute How would this rate change if you were exercising? Why?

Lung volume Using your books (page 50) Fill in the definitions on lung volume and label up your diagram.

Key words Tidal volume Vital capacity The volume of air moved in and out of the lungs at rest (aprox 0.5dm3) The largest volume that can be moved in and out of the lung (aprox 5 dm3)

Some more key words Residual volume Dead space Inspiratory reserve volume Expiratory reserve volume Volume of air that always remains in the lungs Air in the lungs that can not be used in gas exchange (trachea) The volume of air that can be inhaled over the normal tidal volume The volume of air that can be expired over the normal tidal volume

The spirometer and lung volume

Spirometer traces Calculating the oxygen uptake: (diagram a - at rest) Following the same pattern as below, calculate the oxygen uptake for (b) Answer = 1.9dm3min-1 Calculating the oxygen uptake: (diagram a - at rest) Y-axis shows the reduction in chamber total volume by 0.3dm3 between points A&B. The time taken for this reduction is 100-45s So in 55s 0.3dm3 of oxygen is used up. This gives... = 0.3 dm3s-1 55 = 0.3 x 60 dm3min-1 55 = 0.33dm3min-1

Tasks Suggest how a spirometer trace for a trained athlete would differ from a spirometer trace from an untrained individual? Suggest why traces like those on the previous slide are not started immediately as the subject begins to exercise. Answer the rest of question 4 from Jan 2002 paper (2802)

Plenary activity: Answer question 1 and 2 from Jan 2003 paper (2802) Homework: Complete exam question 6 from Jan 2006 paper (2802)

Plenary answers