ANP 1105 Lecture 13: ANP1105 Lecture 13: lesson 13: Lungs

• School: University of Ottawa
• Department: Anatomy and Physiology
• Course: ANP 1105
• Professor: William Staines

Document Summary

Breathing (pulmonary ventilation) = inspiration + expiration. Atmospheric pressure = pressure exerted by air around body (760 mmhg @ sea level) Respiratory pressures described relative to atmospheric pressure. Eg: -4 mm hg respiratory pressure = 760-4. Rises & falls with breathing but always eventually equalizes with atmospheric. ~4 mm hg less than pressure in alveoli (less than atmospheric) Surface tension of pleural fluid + elasticity of chest wall. Any condition equalizing intrapleural pressure with intrapulmonary (or atmospheric) pressure causes immediate lung collapse! Lungs in separate pleural cavities one can collapse & not the other. The roles of the diaphragm & accessory muscles during inspiration and expiration. Increase volume of thoracic cavity decrease pressure of gas inside air rushes in through only opening (trachea) Diaphragm contracts to increase height of thoracic cavity. Intercostals contract to lift rib cage up & pull sternum forward to increase thorax diameter.