Lecture 17 Flashcards
What is boyles law?
Pressure of a gas is inversely proportional to its volume
What is pressure measured from?
The frequency of particle collisions with the container wall
In what direction of pressure will a gas move?
From high pressure to low pressure
When is the pressure inside the lungs in equilibrium with the pressure outside the body?
Right before taking a breath
How does the inhalation cause a pressure gradient?
Volume is increased as the diaphragm drops and the rib cage expands. Pressure inside the lungs decreases and air flows in
How does exhalation cause a pressure gradient?
Volume is decreased as the diaphragm contracts and the rib cage falls. Pressure inside the lungs increases and air flows out.
What are the two opposing forces that we must overcome to take a breath?
Stiffness of the lungs and resistance of the airways
How does the stiffness of the lungs create an opposing force?
Lungs are designed to have high compliance (V/P) to expand however the alveolar fluid exert surface tension to be overcome
What disease causes low compliance of the lungs?
Pulmonary fibrosis
How does pulmonary fibrosis decrease lung compliance?
The alveolar membranes thicken and healthy cells are replaced with scar tissue. This can be caused from chronic inflammation or exposure to industrial chemicals
How is the effect of the alveolar surface tension enhanced?
The thin walls of the alveoli
How do the alveoli disrupt the surface tension?
By producing a surfactant allowing alveoli to expand
What happens when there is a failure to produce adequate surfactant?
difficulty in expanding the lungs and reduced oxygen intake
Why do premature infants sometimes get respiratory distress syndrome?
The alveoli don’t produce surfactant till 28 weeks
What is bronchoconstriction?
The decrease in diameter of the bronchioles
