Mechanics of breathing Lung Volumes Tidal volume The
Mechanics of breathing Lung Volumes: Tidal volume: The volume of air we breath in and out in one breath. Vital capacity: The volume of air forcibly expired after maximum inspiration Residual volume: The volume of air left in the lungs after maximum inspiration Inspiratory reserve volume: The volume of air forcibly expired in addition to tidal volume. Expiratory reserve volume: The volume of air forcibly expired in addition to tidal volume Increase in breathing rate: 1. Increase in CO₂, acidity, decrease in PH. 2. Detected by the chemoreceptors 3. Sends nerve impulses to the respiratory centre in the medulla 4. Nerve impulses are sent to the respiratory muscles (intercostal muscles and diaphragm) 5. They contract more, which increases breathing rate. Inspiration Expiration Intercostal muscles and diaphragm contract Rib cage moves upwards and outwards Lung volume increases Pressure decreases Gases move from a high to low concentration so the air is drawn in Intercostal muscles and diaphragm relax Lung volume decreases Pressure increases Gases move from a high to low concentration so the air is forced out Spirometer trace as a result of exercise: ü Tidal volume increases ü Peaks become more frequent ü Peaks become higher Decrease in breathing rate: 1. Decrease in CO₂, acidity, increase in PH. 2. Detected by the baroreceptors. 3. Sends nerve impulses to the respiratory centre in the medulla 4. Nerve impulses are sent to the respiratory muscles (intercostal muscles and diaphragm) 5. They contract less, which decreases breathing rate. Diffusion: At the lungs and the muscles…. • In the alveoli: high PO₂ low PCO₂ • In the blood/ capillaries: low PCO₂ high PO₂ • Gases move from a high to low pressures • In the muscles: low PO₂ high CO₂ • In the blood/ capillaries: high PO₂ low CO₂ • Gases move from a high to low pressures • Oxygen stored in the myoglobin
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