Prep for USMLEPrep for USMLE
         Forum      |     Resources New Posts   |   Register   |   Login

 lung volumes  

Post Reply  
  • 0/5
  • 1
  • 2
  • 3
  • 4
  • 5

Author4 Posts

can someone explain the relation b/n VC n expiratory air flow n airway rsistance n pleural pressure n elastic recoil??

n wht happens to size of alveoli at FRC?


no one to explain! :cry:


May be I dont undestand the q.. but here we go ...

Vital Capacity (I assume) is the difference b/w TLC and RV, so At TLC the elastic recoil iz at MAX potential, all the force is directed inwards, pleural pressure is as negative as it gets, no expiratory air flow there, since we just took the largest breath IN ever. Pressure n alveolus 0.
As you exhale, pressure in alveouls becomes +, the flow starts and we measure the amount of air exitting with in 1 sec of start and then let the pt exhale to the fullest (to RV) At RV the elastic recoil potential is at MIN, pleral pressure is less negative than at TLC, but more negative than at FRC. I think this covers your question, if not, be more specific, I ll try again.
Size of alveolus at FRC... some (smaller ones) have collapsed, others are at the optimal size. I think whats important is that pressure at FRC in the alveolus is... 0, thats cuz the chest recoil equlas the elastic recoil of lung.
Hope this helps.


thnx for ur efforts ----smiling face

:arrow: at FRC ,alveoli at the base r smaller thn at apex.

:idea: at VC,expiratory flow increases wth increasing pleural pressure,explain.

Bookmark and Share

This thread is closed, so you cannot post a reply.

Login or Register to post messages

show Similar forum topics

alveolar volumes?
kaplan lec note V.S kaplan volumes
show Related resources

Advertise | Support | Premium | Contact