This lesson explains how pressure differences move air and how forces within the thorax keep the lungs expanded.
Respiratory pressures are often described relative to atmospheric pressure. Atmospheric pressure is treated as zero; pressure above it is positive, and pressure below it is negative. Because the alveoli connect to the atmosphere through the airways, intra-alveolar pressure returns to atmospheric pressure when airflow stops.
All flashcards
What is pulmonary ventilation?
Pulmonary ventilation is breathing: the movement of air into and out of the lungs.
What is intra-alveolar pressure?
It is the pressure of the air inside the alveoli. It changes during breathing and equalizes with atmospheric pressure when airflow stops.
State Boyle’s law in relation to breathing.
At constant temperature, pressure and volume are inversely related. Expanding lung volume lowers pressure; reducing volume raises pressure.
Why is intrapleural pressure normally negative?
The lungs tend to recoil inward while the pleural fluid and thoracic wall exert opposing outward forces. The slight balance favoring outward pull keeps intrapleural pressure below alveolar pressure.
What is transpulmonary pressure?
It is the pressure difference between intra-alveolar and intrapleural pressures. A higher transpulmonary pressure corresponds to a larger lung.
Quiz questions
When does intra-alveolar pressure return to atmospheric pressure?Answer: When airflow stops.
Which muscles help produce forced expiration?Answer: Abdominal muscles and internal intercostals.
What effect does reduced thoracic wall compliance have on breathing?Answer: It makes thoracic expansion more difficult.
What is a key role of the dorsal respiratory group in the medulla?Answer: Integrating sensory input and helping adjust the breathing pattern.
How does obstructive sleep apnea differ from central sleep apnea?Answer: Obstructive apnea involves airflow blockage; central apnea involves inadequate respiratory-center signaling.
Based on Anatomy and Physiology 2e by J. Gordon Betts, Kelly A. Young, James A. Wise, Eddie Johnson, Brandon Poe, Dean H. Kruse, Oksana Korol, Jody E. Johnson, Mark Womble, Peter DeSaix (OpenStax), licensed CC BY 4.0. Adapted into a summary, flashcards and quizzes.