ENS 332 Lecture Notes - Lecture 9: Mount Everest, Intrapleural Pressure, Thoracic Wall
12 Jan 2017
School
Department
Course
Professor
Document Summary
Po2 of 90 torr is about 4000m (pikes peak: mount everest is less than 50 torr. Atmosphere lungs across blood-gas barrier circulation capillary bed muscle. When the diaphragm contracts, the lung is well ventilated: high o2 and low co2 in the lungs blood is similar. When blood leaves the pulmonary capillary: o2 matches the tension in the lung, co2 is slow. Alveolar po2 = 100 mmhg: therefore, arterial po2 = 100 mmhg. At maximal exercise: the mitochondrial po2 is about nothing, there is not zero po2 in the mitochondria, may be a fraction of 1 mmhg. At the end of a quiet expiration: the intrapulmonary pressure equals the atmospheric pressure (760 mmhg, expiration is mostly passive. Pleural cavity: has a negative intrapleural pressure (~756 mmhg) So the lungs do not collapse on itself. If the lungs get punctured in the thoracic wall and atmospheric air is introduced, a pneumothorax (air in the thorax) occurs.
