BIOL 221 Lecture Notes - Lecture 7: Intrapleural Pressure, Thoracic Cavity
3 Mar 2020
School
Department
Course
Professor
Document Summary
For inspiration, intra-alveolar pressure (palv) must be less than atmospheric pressure (patm). For expiration, intra-alveolar pressure (palv) must be greater than atmospheric pressure (patm). Share your answers by posting on the discussion board. At end of expiration, palv = patm. At the end of expiration, pressure in the alveoli (palv) is equal to atmospheric pressure (patm) and there is no flow of air. During inspiration, muscles contract thoracic cavity expands ppl decreases lungs expand palv decreases to becomes less than. At end of inspiration, palv = patm. During inspiration, the thoracic cavity volume increases, therefore, intrapleural pressure (ppl) decreases and the lungs expand (volume increases). As a result, intra-alveolar pressure (palv) decreases to become less than atmospheric pressure (patm). Air enters the lungs due to the pressure gradient. At the end of inspiration, pressure in the alveoli (palv) is equal to atmospheric pressure (patm) and there is no flow of air.
