Step I physiology

[hematosis]

Is the movement of Na+ through a sodium channel considered a Simple diffusion or Facilitative diffusion. It was my understanding that because sodium is an ion and cannot permeate the membrane, it requiers a protein channel. Further, because a protein is used to facilitate its movement, it would be considered facilitative diffusion. However, today our professor described it as a simple diffusion. His reasoning was that the channel does not act as a carrier, rather it simply opens and sodium diffuses through. therefore, its not carrier mediated (as opposed to glucose) could anyone shed some light on this simple subject?

 

[absolutdokta]

Is the movement of Na+ through a sodium channel considered a Simple diffusion or Facilitative diffusion. It was my understanding that because sodium is an ion and cannot permeate the membrane, it requiers a protein channel. Further, because a protein is used to facilitate its movement, it would be considered facilitative diffusion. However, today our professor described it as a simple diffusion. His reasoning was that the channel does not act as a carrier, rather it simply opens and sodium diffuses through. therefore, its not carrier mediated (as opposed to glucose) could anyone shed some light on this simple subject?

I actually just went through the first chapter of my brs phys book and it talks about how facilitated transport involves stereospecific mediators. So if the channel is strictly for Na+ ions i'd say its facilitated since the part about having that mediator is the only thing that separates simple and facilitated diffusion. simple: no stereospecific mediator, facilitated: sterospecific mediator