Hello!

I just posted on this subject but it appears to have disappeared! So apologies if you now get two posts from me... However, now I've found the sheet with the actual question on, I might be able to get some more direct help!

I'm doing an A level in biology and I'm stuck. The question is:


The capillaries in the lungs are very small in diameter. As a result, blood travels through them slowly. Explain two ways in which the small diameter of the capillaries results in the efficient transfer of oxygen from the alveoli to the red blood cells.



I've already established that our teacher is not a very good teacher, so myself and the other students have been relying on our text books and the internet to answer questions. However, this one isn't mentioned in our books and I can't find an answer on Google. Does anyone have any suggestions? The only thing I can think of is that the slow movement of the blood allows more time for the gas exchange to occur, and maybe that the small diameter (meaning only one blood cell at a time can pass through the capillary) means that the alveoli always have access to the complete surface of the blood cell, rather than having bits of two cells passing the alveolar wall..? Oh, I don't know!

I've moved this to Homework Help where it will get better "reception". See the first couple links here for a little reading pending someone coming along with a more specific answer.

Thank you for moving it to a better area! I wasn't sure where to ask it, but I've a feeling I'll be visiting this section of the website quite regularly over the next year! Also, tried to give you kudos but it wouldn't let me... So please accept virtual kudos :)