Muscle question

[Raiden2012]

---

Members don't see this ad.

When acetylcholine crosses the synapse and binds to the post synaptic membrane to cause depolarization in a muscle cell, does it cause the opening of voltage gated Na or Ca channels?

I was thinking Na because an AP hasn't been generated yet to cause opening of the Ca channels. The muscle is still in the process of depolarization. But if it has crossed the threshold, then Ca would be the answer.

Thoughts?

 

[Temperature101]

When acetylcholine crosses the synapse and binds to the post synaptic membrane to cause depolarization in a muscle cell, does it cause the opening of voltage gated Na or Ca channels?

I was thinking Na because an AP hasn't been generated yet to cause opening of the Ca channels. The muscle is still in the process of depolarization. But if it has crossed the threshold, then Ca would be the answer.

Thoughts?

It causes the valtage gate Na+ channel to open--not Ca++.

 

[Raiden2012]

Thanks that was my answer too until I saw the book's answer. So when exactly do the Ca++ channels open? After AP?

 

[Temperature101]

Thanks that was my answer too until I saw the book's answer. So when exactly do the Ca++ channels open? After AP?

When the action potential propagated, it cause Ca++ gated channel to open at the presynaptic terminal. Ca++ diffuse into the cell causing ACh to be released into synaptic terminal, which in turn cause Na++ gated channel to open into the next cell for the action potential to continue.

 

[Raiden2012]

Isn't that for a neuron though? Aren't muscles slightly different with the sarcoplasmic reticulum induced release and the voltage gated calcium channels as well?

 

[Temperature101]

Isn't that for a neuron though? Aren't muscles slightly different with the sarcoplasmic reticulum induced release and the voltage gated calcium channels as well?

Sorry..I meant next muscle cell. Cant beleive I wrote neuron.
http://highered.mcgraw-hill.com/sit...r14/animation__chemical_synapse__quiz_1_.html
This animation will clear things up for you.

 

[Raiden2012]

Thanks!

I guess I must have messed up the Ca++ channels. I initially thought there would be Ca++ influx in muscle after an action potential

 

[bored]

Thanks!

I guess I must have messed up the Ca++ channels. I initially thought there would be Ca++ influx in muscle after an action potential

um.. I think there is.

ok Ach binds to ligand gated Na+ channels, allowing Na to come in. this passes througth the T tubules. as well.
muscle cell is now activated.

the depolarization in the muscle cells causes voltage gated Ca2+ channes of the muscles cells to open ( = Ca2+ in), also Voltage gated Ca2+ channels of the Sarcoplasmatic Reticulum open and more Ca2+ enters the muscle cell.

 

[Raiden2012]

um.. I think there is.

ok Ach binds to ligand gated Na+ channels, allowing Na to come in. this passes througth the T tubules. as well.
muscle cell is now activated.

the depolarization in the muscle cells causes voltage gated Ca2+ channes of the muscles cells to open ( = Ca2+ in), also Voltage gated Ca2+ channels of the Sarcoplasmatic Reticulum open and more Ca2+ enters the muscle cell.

Oh thanks, I remembered something about Ca++ channels.But this brings us back to the first question, depolarization causes Na or Ca channels to open? Answer seems to be both if that's the case. Na followed by Ca

 

[bored]

Oh thanks, I remembered something about Ca++ channels.But this brings us back to the first question, depolarization causes Na or Ca channels to open? Answer seems to be both if that's the case. Na followed by Ca

i guess you could say the following

ach binding to ligand gated sodium channels, which causes depolarization, which causes opening of voltage gated calcium channels.

 

[Raiden2012]

Ok thanks!

 

[Reneeisnowhere]

Wow, thanks for the link!

Renee