West's 9th ed - Chapter 1 - Structure and Function (1) Flashcards
Do terminal bronchioles have alveoli attached?
No. The terminal bronchioles are the smallest generation of the conducting airways, which constitute anatomical dead space, and take no part in gas exchange.
What is an acinus?
This is the portion of lung that is distal to a singular terminal bronchiole, forming an anatomical unit that functions in gas exchange.
What is the respiratory zone of the lung?
This is the regions of the lung that contain alveoli. This excludes the dead space of the conducting airways.
How many generations are in the conducting airways? How many are in the respiratory zone?
Conducting: 16. Respiratory: 7.
How does the total cross-sectional area of the respiratory zone compare to that of the conducting zone? What effect does this have on gas movement?
The cross-sectional area increases exponentially as you move from the conducting zone to the respiratory zone. This slows down the speed of gas travel significantly. Whilst gas moves through the conducting zone by convective flow, it becomes dependent on diffusion to drive its movement through the respiratory zone.
What is the thickness of the blood-gas interface?
Extremely thin. About 0.2-0.3µm.
What is the diameter of a pulmonary capillary?
About 7-10µm, which is only just big enough to allow passage of a red blood cell.
What is the diameter of an alveolus?
Approx 0.3mm
How do you figure out the partial pressure of a gas in the plasma?
This is found by multiplying its concentration by the total pressure. Dry air has 21% oxygen. Barometric pressure at sea level is 760mmHg, and then you have to subtract the water vapour pressure of 47mmHg due to moist airways. The PO2 of inspired air is therefore 0.21 x (760 - 47)
