Chapter 37 - Guyton Flashcards
Define pulmonary ventilation.
inflow and outflow of air between the atmosphere and the lung alveoli
What is primarily responsible for expiration?
elastic recoil of the lungs, chest wall, and abdominal structures compresses the lungs
Muscles that help raise the ribcage during inspiration?
external intercostals, SCM, serratus anterior, scaleni
During heavy breathing, which muscles aid expiration?
abdominal muscles (internal intercostals also)
Pleural pressure
the pressure of the fluid in the thin space between the lung pleura and the chest wall pleura
What change occurs in the pleural pressure during inspiration?
expansion of the chest cage pulls outward on the lungs with greater force and creates more negative pressure (-5 to -8)
Alveolar pressure
the pressure of the air inside the lung alveoli
What change occurs in alveolar pressure during inspiration?
to drive air in, the pressure must fall (0 to -1 then +1 during expiration)
What is transpulmonary or recoil pressure?
the difference in pressure between the outer surface of the lungs and the alveoli, it is a measure of the elastic forces
What is lung compliance?
the extent to which the lungs will expand for each unit increase in transpulmonary pressure (200 mL)
The elastic forces of the lung tissue are determined
mainly by _____ and ______ fibers interwoven
among the lung parenchyma.
elastin, collagen
What is primarily responsible for collapse of the lungs, which force?
fluid-air surface tension forces in the alveoli represent about two thirds (rather than tissue elastic forces)
Secrete surfactant in the lungs.
type II alveolar epithelial cells
Primary role of surfactant?
greatly reduces the surface tension of water
Spirometry
record the volume movement of air into and out
of the lungs
