starbrite520
Forum Guru
Topics: 131
Posts: 427
|
so awkward but i ALWAYS forget ewhat perfusion lmited and diffusion limited and ventilation limited means. my notes just arent clear . can someone dumb it down-kindly.
|
| Auron
Forum Newbie
Topics: 1
Posts: 11
|
Its been awhile, but if I remember correctly, perfusion limited indicates that the O2 present in the alveoli equilibrates into the capillaries early in the course of the particular capillaries travel across an alveolus.. In essence, each unit/volume/amount of blood that passes through the capillary surrounding the alveolus is oxygenated as fully as it can be.
Diffusion limited indicates that oxygen is diffusing more slowly into the capillaries(usually as a result of some sort of lung disease such as idiopathic pulmonary fribrosis etc) so that each volume of blood that passes through the capillary is NOT fully saturated with oxygen at the distal end of the capillary for that particular alveolus.
I'm pretty sure there could be more precise definitions but its very difficult to describe in words.
Another way of saying the same thing is if you view a theoretical alveolus with a capillary which contacts the alveolus for a total of 10 "units", in perfusion limited, the blood is fully oxygenated at unit 1-3 (or up to 9-10 really as long as its fully oxygenated before it gets past 10) where as in diffusion limited, the blood is never fully oxygenated even at unit 10.
Once again, i'm not sure this description is completely physiologically correct, its more of a model in my head to get the essence of whats going on.
|
|
| |
| | |
