Expert: Dana Krempels, Ph.D. - 12/3/2007

Question
Hi there,

I have done research and research, but I am not completely sure about 3 parts of it.



1)The process of oxygen being inhaled in the atmosphere of how oxygen end up in the alveoli. ( I thought oxygen was inhaled into our lungs where it diffuses with the cell walls of the lungs, I never encounter how it ends up in the alveoli.



2) How the oxygen we inhale enteres blood and is then gets delivered to the quadriceps muscles?



3) My last questions I am concerned with how when there is an open wound. The mechanism of clotting prevent bleeding? (i really though that platelets stopped the bleeding by adhesion, then releases A2 and ADP, then fibril expand to coneect them, I am super confused!) And if it isnt platelet how does the red blood cell and other componenets of the blood be used in this mechanism? I am very confused, and I have done my reading, I don't know where it went wrong! please help me.

Answer
Dear Jeffrey,

1.  The alveoli *are* part of the lungs.  They are the tiny, microscopic, saclike structures, each suffused with capillaries, where gas exchange takes place between the inhaled atmosphere and the blood.

2.  Once oxygen passes into the bloodstream from the alveoli, it is transported all over the body, including to all the muscles, via the complex network of blood vessels.

3.  You've listed the components of clotting pretty well, but I'm not sure where you're confused.  A lot of this requires visualizing cellular mechanisms.  You can find a very clear overview here:

http://heartdisease.about.com/cs/heartattacks/a/clotting.htm

Hope that helps get you started on a clearer understanding.  Good luck,

Dana