PHYSL210B Lecture 2: Ventilation
Document Summary
Static condition in a normal respiratory system no airflow. Negative relative pressure of 5 cm h2o around the lungs keep the lungs open. We measure relative pressure: pressure difference (pressure c pressure) C pressure= 760 mmhg or 0 cm h2o. Immediate space around the lungs (pleural space pressure) is in a little less pressure so negative relative pressure is generated. Pressure at the bottom of the lungs is greater than the pressure at the top because of gravity. Pleural space= space between the lungs and the chest wall (pleural pressure/ interpleural pressure is the same thing) Visceral pleura- intrapleural space- parietal pleura these three make up the pleural sac. Airflow (v) is proportional to the difference between alveolar pressure (pa) and atmospheric pressure (pb), but inversely proportional to airway resistance (r). V = (alveolar pressure atmospheric pressure)/ airway resistance. Resistance might go up if diameter of bronchioles decreases. To create airflow, we need to manipulate alveolar pressure.