PPoS 0.0 / 5 ? MedicinePhysiologyUniversityAll boards Created by: amiedesancha_Created on: 01-05-17 18:53 Boyle's law PV = constant, therefore increase in pressure decrease in volume 1 of 23 How are the lungs mechanically coupled to the chest wall Pleural fluid 2 of 23 During inspiration what happens to the intrapleural pressure It decreases (increased volume and therefore decreased pressure) 3 of 23 Air is drawn into the lungs when pressure is less or greater than barometric Less 4 of 23 What muscles are always inspiratory muscles Diaphragm, ext. IC, scalenes, parasternal IC (prevents wall collapsing inwards) 5 of 23 What are accessory muscles of inspiration Neck muscles, e.g. SCM 6 of 23 Expiratory muscles include... Int. EC, rectus abdominus, EO, IO, TA (however in normal breathing expiratory is just the relaxation of Inspiratory muscles) 7 of 23 What is functional residual capacity? Volume of air in the lung at the end of a normal breath 8 of 23 Transpulmonary pressure = alveolar pressure - intrapleural 9 of 23 Why is intrapleural pressure negative during inspiration Opposes inwards elastic recoil 10 of 23 transpulmonary pressure is also known as Distending pressure (decreases during respiration 11 of 23 Why does a pneumothorax, punctured chest wall, cause the lung to collapse Intrapleural pressure becomes equal to atmospheric 12 of 23 Anatomic dead space is ~ 150ml 13 of 23 Equation for alveolar ventillation = minute ventilation - dead space 14 of 23 When inhaling, inspiratory muscles must overcome Elastic resistance and airway resistance 15 of 23 Equation for lung compliance Change in lung volume / change in transmural pressure gradient 16 of 23 Equation for airway resistance Alveolar pressure - mouth pressure / airflow at mouth 17 of 23 Where are the main sites of reistance in the airway Nose, pharynx, larynx, medium sized bronchioles (gen3-5) 18 of 23 +ve intrapleural pressure keeps airways open or causes them to collapse Collapse (forced expiration) 19 of 23 Why is it that expiratory airlow is limited at a low lung volume and does not increase with increased force Dynamic compression 20 of 23 What occurs in normal people but more readily if high resistance Dynamic compression 21 of 23 What generation of bronchioles are most likely to collapse 3-4 22 of 23 An increased airway resistance leads to... slow expiration and low peak flow expiratory flow rate 23 of 23
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