How are neurotransmitters reuptaken?

[Turkelton]

---

Members don't see this ad.

I've been studying the TPR book, and they don't really explain the answer to this one.
Does anyone know how nt's are reuptaken?

A.) Osmosis
B.) Simple Diffusion
C.) Facilitated diffusion
D.) Primary Active transport

 

[HawkeyePostOp]

Primary Active Transport
the vesicles transport the transmitter back to the synaptic terminal

some are also degraded into their components by enzymes i.e. acetylcholinesterase for acetylcholine.

 

[spyderracing32]

Vesicles facilitate the release of NTs into the synapse, they do not aid in the reuptake. Reuptake occurs by neurotransmitter tranport proteins on the presynaptic membrane (from which the NTs are released). These are generally Na+ dependant co-transport proteins. There is not ATP involved or any other energy expenditure so it is not Primary Active Transport. I would think facilitated diffusion should be the correct answer.


The other methods of NT removal are:
1) enzymatic destruction as described by hawkeye
and
2) simple diffusion away from the synapse

 

[AZFutureDoc]

Would I be wrong to just POE this question? I mean A and B are just dumb, and C couldn't happen because the concentration gradient would be working against it. No fac. diff. is going to get NT's back inside!

 

[spyderracing32]

Would I be wrong to just POE this question? I mean A and B are just dumb, and C couldn't happen because the concentration gradient would be working against it. No fac. diff. is going to get NT's back inside!

Neurotransmitters are stored in synaptic vesicles, there is no concentration gradient.

 

[Turkelton]

So from the answers posted I'm not sure if it's facilitated diffusion or primary active transport. I kind of agree with what spyderracing 32 is saying. Isn't it a requirement of primary active transport to use ATP. Does anyone know if ATP is used during reuptake???

 

[spyderracing32]

So from the answers posted I'm not sure if it's facilitated diffusion or primary active transport. I kind of agree with what spyderracing 32 is saying. Isn't it a requirement of primary active transport to use ATP. Does anyone know if ATP is used during reuptake???

Well what answer are they giving. I'm a neurosci major and don't recall it being an active transport situation, and after going back to the books it doesn't mention anything about there being any kind of active transport. It's an Na+ and sometimes Cl- dependant co-transport (like with sugar and protein digestion). I know these aren't active transport systems.

 

[Turkelton]

The book was purchased used, and that particular answer page in the back of book is torn out. After looking in my physiology textbook is says the friggin answer is secondary active transport which is even more confusing. A quote from the physio text:

"These secondary active transport systems use the normal ionic gradients of Na+, K+, H+, or Cl- to achieve concentrative uptake of transmitter".

Also I went on wikipedia (which can be inaccurate/unreliable) and here is it's quote:

"The neurotransmitter in question will bind to sodium ions, where the sodium ion will flow down its concentration gradient as well as electrical gradient. These forces will pull the neurotransmitter into the cell, against its own gradients"

So for the 4 answers given originally it's going to be facilitated diffusion because that answer is the least wrong. The answer is definitely not Primary Active Transport. However if secondary active transport was an answer option I would pick that instead of facilitated diffusion b/c both "Medical Physiology" and "Wikiped" contain that in their explanations.

 

[HawkeyePostOp]

Vesicles facilitate the release of NTs into the synapse, they do not aid in the reuptake. Reuptake occurs by neurotransmitter tranport proteins on the presynaptic membrane (from which the NTs are released). These are generally Na+ dependant co-transport proteins. There is not ATP involved or any other energy expenditure so it is not Primary Active Transport. I would think facilitated diffusion should be the correct answer.


The other methods of NT removal are:
1) enzymatic destruction as described by hawkeye
and
2) simple diffusion away from the synapse

yeah my bad I'm ******ed.
they are actively transported back to the synaptic terminals, and only then packaged into vesicles.
Facilitated diffusion makes the most sense then.

 

[alum]

ATP is used; therefore, active transport. Good luck to you.

I've been studying the TPR book, and they don't really explain the answer to this one.
Does anyone know how nt's are reuptaken?

A.) Osmosis
B.) Simple Diffusion
C.) Facilitated diffusion
D.) Primary Active transport

 

[spyderracing32]

ATP is used; therefore, active transport. Good luck to you.

I don't think so. Think about the energy expenditure that would entail if every time a neurotransmitter was released you needed ATP to facilitate reuptake?

 

[HawkeyePostOp]

It looks like it's badly set up question

my bio book is in front of me:
"Non-degraded neurotransmitters such as biogenic amines are actively transported back into the synaptic terminals, a process known as reuptake. These neurotransmitters are repackaged in vesicles and recycled."

Since the writer made the answer C, he's either wrong or is referring to a different stage in the process.