Respiration Lecture 03: Volumes and Ventilation Flashcards
breath
an inspiration and subsequent expiration
Tidal volume
amt. of air brought in and out of lung w/ each normal breath
2 phases of a breath
inflation (inspiration) and deflation (expiration)
airflow
rate at which gas moves
alveolar pressure is _____during inspiration, ____at rest, and ______during expiration
negative, 0, positive
What affects airflow into/out of lung?
driving force (change in pressure) and forces that resist movement of air
pleural pressure is ______during inspiration, ______at rest, and ______during expiration
negative, more negative, negative
the tendency of the lung to collapse is due to:
tissue forces that oppose lung expansion
compliance
relationship between the change in volume and change in pressure. The “stretchability of the system.” Is directly related to the physical properties of the system
surface tension
force that acts at gas-liquid interface which tends to reduce the surface area of the interface. Pulls like molecules towards eachother and reduces area of the air-liquid interface by i.e. collapsing an air bubble, creating a pressure in the air bubble which opposes this force
Laplace Law
describes the pressure required to keep bubble/alveolus open. P = 2t/r where t is wall tension and r is radius of bubble/alveolus
What size alveolus have the greatest tendency to collapse?
small
surfactant
substance that works to reduce the air-liquid interface
Where is surfactant produced?
Alveolar Type II cells
Consequences of surfactant insufficiency
lung can’t expand as easily, alveoli may collapse, alveoli will flood with fluid from capillaries (surfactant helps keep alveoli dry)
