Topics
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4. Ventilation and Perfusion
Subheadings:– Ventilation-perfusion (V/Q) relationship– Dead space– Shunt– Pulmonary circulation Ventilation Perfusion (V/Q) relationship Ventilation (V) refers to the movement of air into an alveolar space, whilst perfusion (Q) is the flow of blood to an alveolar space. Ventilation and perfusion are two partners of a relationship that is required for gas exchange. There are numerous…
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3. Lung Volumes and FRC
Lung volumes and capacities Lung volumes refer to the volume of gas within the lungs at different times during the inspiratory cycle. Normal tidal breathing, which is the respiratory pattern when at rest, has a volume (tidal volume) of around 500ml, including both inspiration and expiration. At end inspiration on tidal breathing, we still have…
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2. Mechanics of Breathing
Subheadings:– Lung pressures– Compliance – Resistance – The act of breathing Lung Pressures What stops the lungs just collapsing down? What keeps them open? The answer is a dynamic, constant tension of outward and inward forces, resulting in an equilibrium that keeps the lungs open. The main equation that explains how lungs remain open is:…