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Spot the difference!. Atmospheric pressure 760mm Hg Intra- alveolar pressure 758mm Hg. Atmospheric pressure 760mm Hg Intra- alveolar pressure 760mm Hg. A mobile ribcage?. This means that the rib cage must also be able to change position.
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Spot the difference! Atmospheric pressure 760mm Hg Intra- alveolar pressure 758mm Hg Atmospheric pressure 760mm Hg Intra- alveolar pressure 760mm Hg
A mobile ribcage? This means that the rib cage must also be able to change position. Take your hands and place them flat on your chest just above your hips on each side of your body. Now breathe in and out very deeply. Whilst you do this, watch to see what happens to your hands. You should notice the following things…..
Make a table like this: Complete the table by writing the sentences on the next slide in the correct order. Outline the mechanism of breathing in mammals, with reference to the function of the ribcage, intercostal muscles and diaphragm (Grade A – B)
Breathing in and out • Pressure in lungs decreases. • Volume of chest cavity decreases • Diaphragm relaxes and is pushed upwards by displaced organs underneath • External intercostalmuscles relaxand ribs fall • Pressure in lungs increases. • Air moves out of the lungs. • Diaphragm contracts to become flatter and pushes digestive organs down • Volume of chest cavity increases • External intercostal muscles contract to raise ribs • Air moves into the lungs.
Pressure changes The pressure changes in the lungs are brought about by the movement of 2 sets of muscles: • The diaphragm – a sheet of muscle that separates the thorax and the abdomen. • The intercostal muscles: • Internal intercostal muscles – contraction leads to expiration • External intercostal muscles – contraction leads to inspiration
The diaphragm Your diaphragm is located beneath the lungs, which means that it separates the thorax from the abdomen. It is a sheet of muscle that spans the width of the body. Before we inhale, it is found in a dome shape. As we inhale, it contracts andflattens. The result of this change in shape is a change in the volume of the thorax. inhaling
Pressure regulation • High air pressure outside High • Low air pressure inside • Air diffuses into the lungs Low • Diaphragm flattens • Thorax volume increases • Air pressure drops As the volume of the thorax increases, the internal air pressure drops. This means that the air pressure outside the lungs is greater than the air pressure inside the lungs.
Module 2Exchange and transport 1.2.4 Measuring lung capacity
Success Criteria Learning Objectives Understand how to measure lung capacity To be able to label a spirometer trace (PSHE LINK:SMOKING, FITNESS, LUNG CAPACITY) Define the terms tidal volume and vital capacity (Grade E - D) Describe how a spirometer can be used to measure vital capacity, tidal volume, breathing rate and oxygen uptake (Grade C –B) Analyse and interpret data from a spirometer (Grade B – A)
Starter – Measure your peak flow using a peak flow meter Peak flow meter • Measure the peak expiratory flow rate (maximum flow of air that can be forced out of the lungs). • This can show if the airway is blocked in any way. • Used by asthmatics who can check to see if medication is working. A “normal” value should be between 400-600 dm3min-1
Describe how a spirometer can be used to measure vital capacity, tidal volume, breathing rate and oxygen uptake (Grade C –B) Spirometer and lung volume A spirometer consists of a chamber filled with oxygen that floats on water. A person breathes from a mouthpiece attached to a tube connected to the chamber. Breathing in takes in oxygen from the chamber, which then sinks down Breathing out pushes air into the chamber, which then floats up. These movements are recorded using a data logger, so a trace is recorded. Soda lime – absorbs carbon dioxide exhaled, if the level increases dangerously. So the total volume of gas in the spirometer goes down. The volume of carbon dioxide breathed out is the same as the volume of oxygen breathed in, so this reduction can be measured allowing us to work out the total oxygen.
Spirometry • Describe how a spirometer can be used to measure vital capacity, tidal volume, breathing rate and oxygen uptake (Grade C –B)
Key definitions • Tidal Volume - The volume of air inhaled and exhaled at each breath, this is normally equivalent to only 10% of the total 5L volume of the trachea and lungs. • Residual Volume - the amount of air still remaining in the lungs after the most forceful expiration. • Vital Capacity - the maximum amount of air that can be exhaled after a maximum inhalation. • Training can increase the strength of the diaphragm and intercostal muscles and can thus raise the vital capacity and hence improve performance.
Spirometer trace – Label your diagram use page 50 • Define the terms tidal volume and vital capacity (Grade E - D)
Analyse and interpret data from a spirometer (Grade B – A) Task • Students to use the spirometer and analyse the data on their trace, commenting on their lung capacity – Collection of quantitative data (nose clip not available – why is this important?) • Answer questions 1-5 on page 51 • Self mark answers • Describe how a spirometer can be used to measure vital capacity, tidal volume, breathing rate and oxygen uptake (Grade C –B)
Self assessment • Analyse and interpret data from a spirometer (Grade B – A) • Diffusion • A) tidal volume – 0.3dm3 breaths per minute – 13 B) tidal volume – 1 dm3 breaths per minute – 22 3. 2 dm3min-1 4. Larger tidal volume and more breaths per minute 5. So tidal volume and breathing rate increase Show of hands - /8
Plenary • Jeopardy: Students have to write the question when given the answer. • Tidal volume • Vital capacity • Breathing rate • Soda lime • Spirometer • Inspiration • Expiration
