Dear Experts,

 

 

A stupid question-

Do all blood vessels in the human body have semipermeable membranes?

i.e.- do also veins have semipermeable membranes that allow penetration of small molecules ?

Can someone please give me a reference for this fact ?

 

 

Thanks !

I don't know the answer for this exactly, but I would imagine that some vessels are more or less permeable depending on where they are in the body and how thick the walls of the vessel are. I think that veins and arteries have a layer of smooth muscle surrounding them (among other things), so it follows that they wouldn't be particularly permeable compared to capillaries (which don't consist of much and are responsible for the actual exchange of molecules in and out of the circulatory system), if they were permeable at all.

You should really define what the membrane is supposed to be semi-permeable to. I assume you are asking about molecular oxygen, but it's best to be specific.

 

Anyway, veins and arteries consist of 3 layers which makes them fairly non-permeable. The capillaries are pretty much just thin endothelium to allow oxygen permeability.

Sounds reasonable. Thanks a lot !