"Medical Physiology Pulmonary Mechanics II Amit S. Dhamoon" SANA Flashcards
Why does the compliance decrease at very high lung volumes?
As the lung fills up more, it is less able to stretch
What is hysteresis?
The biophysical observation that the volume/pressure curve is different for inflation and deflation of the lungs
If you remove all water from a lung and fill it in with saline instead, what will happen to the compliance?
The compliance will increased
If you remove all water from a lung and fill it in with saline instead, will hysteresis be observed?
No
What is the function of surfactant?
Decreased surface tension
A premature infant is born with infant respiratory distress. If saline is administered into the infant’s lungs, what will happen to the compliance?
Because the baby is born without surfactant, the compliance of the lung is very low. The saline will increase the compliance.
Your geriatric patient comes in with a collapsed lung. How compliant is his lung at this point? Why?
Very un-compliant, making it harder to ventilate since surfactant production goes down in a collapsed lung.
In cases of pneumothorax, the intrapleural pressure is ____ and the alveolar pressure is ____
both 0
Name one disease in which the lung is TOO compliant?
Emphysema
Which of the following stages of breathing is most difficult for an emphysema patient?
a. inhalation
b. exhalation
exhalation is more difficult as the lung compliance is too high due to elasticity being lost, leading to air being trapped in the lungs.
According to LaPlace’s law, if two bubbles of different sizes have the same surface tension, which one will have a larger internal pressure?
smaller bubble
The lung has alveoli in various sizes. What is keeping the smaller alveoli from emptying into the larger ones, as would be predicted by LaPlace’s law since smaller alveoli have higher internal pressures?
The surfactant reduces the surface tension of the alveoli. Because it is less concentrated on the surface of the larger alveoli (which have greater radius), and more concentrated on smaller alveoli, the surface tensions balance out between the two different sizes, causing them to be stable.
What is the functional residual capacity (FRC)?
The FRC represents the equilibrium between the chest wall and the lungs, when the outward recoil force of the chest is equal to the inward recoil force of the lungs.
How can you change your residual volume?
You can’t, that’s the air that’s still in your lungs once you have expired as much as you can. There will always be some air left in your lungs.
What does the FRC represent in terms of the stages of breathing?
It is the point when you’re getting ready to take another breath
