Respiratory 18 Flashcards
What does the Radioactive Xenon test demonstrate?
How ventilation is not equal in different regions of the lungs
What occurs during the Radioactive Xenon test?
A patient is asked to inhale and hold his breath. The radioactivity of the chest wall is measured by counters. The amount of radioactivity measured is an indication of how much air is inhaled in different regions of the lung
Where is ventilation highest in the lungs?
In the lower zone of the lung
Where is ventilation lowest in the lungs?
In the higher zone of the lungs
When an individual is lying down where is ventilation greatest?
At the bottom of the lungs near the back
When an individual is doing a handstand where is ventilation of the lungs greatest?
The upper zone
What kind of pressure is present in the intrapleural space?
Negative pressure
How does the intrapleural pressure change in different parts of the lung?
The intrapleural pressure is much more negative at the bottom of the lung than compared to the top of the lung
What is intrapleural pressure generated by?
The balance between the elastic recoil of the lung and the elastic chest wall
How do the different intrapleural pressures affect lung volume?
A less negative intrapleural will cause a large increase in lung volume. A more negative intrapleural pressure will cause reduce the change in lung volume
Why is there more ventilation in the bottom alveoli?
Because they are starting more deflated because they have an increased (more negative) intrapleural pressure and are able to expand more and take in more air
Why is there less ventilation in the top alveoli?
Because there is less intrapleural pressure aos they are already expanded so they cannot expand much more to increase ventilation
