***Official***The help doc3232 thread in bio ;)

[doc3232]

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So as you can see it is the official one...

1. Acetylcholine is a neurotransmitter that is always excitatory and also lets Na+ into the postsynaptic thread? So does that mean neuron cell to neuron cell synapses would be the same as neuromuscular junctions or at least similar in some cases?

2. How does temporal summation and spatial summation work? I partially understood spatial summation, but I didn't understand temporal summation.

3. Monosynaptic reflex arc is made up of only 2 neurons and 1 synapse? The only examples in my book had a sensory neuron that ran through the spinal cord and ran through an interneuron (that was in the spinal cord). What is an example of one and how does it work?

4. So if Na+ channels are left open then Na will be in the cell and out of the cell equally, but the potassium channel is closed and the sodium potassium pump is still running. That would force all of the Potassium into the cell to be very positive right? Different scenario: And if the potassium channels were open and sodium ones are closed then the pump would cause all the sodium out of the cell. Would the cell reach -70 or would the sodium come back into the cell to stabalize the negative charge? This is only a hypothetical situation.

5. Nodes of Ranvier, I know they allow us to use less ATP on the pumps by minimizing the area, but how does that work out? Wouldn't the areas that are myelinated also need to repolarized, hence using the same amount of ATP?

6. Spinal cord controls our primitive processes? All of them?

So. That took a while to write.

Thanks in advance for your help

 

[doc3232]

bump...I am patient 🙂🙂🙂🙂

 

[chocolateeth]

omy i don't think Bio section on the DAT is this detailed.... :-X

 

[shoombol tallah]

Im pretty sure acetycholine is both excitatory and inhibitory. It is excitatory in the neuromuscular junction and inhibitory everywhere else.

 

[PinkDDS]

1. Acetylcholine is a neurotransmitter that is always excitatory and also lets Na+ into the postsynaptic thread? So does that mean neuron cell to neuron cell synapses would be the same as neuromuscular junctions or at least similar in some cases?


2. How does temporal summation and spatial summation work? I partially understood spatial summation, but I didn't understand temporal summation.
check out this link :
http://hsc.uwe.ac.uk/synapses_neuro/Summation.htm

3. Monosynaptic reflex arc is made up of only 2 neurons and 1 synapse? The only examples in my book had a sensory neuron that ran through the spinal cord and ran through an interneuron (that was in the spinal cord). What is an example of one and how does it work?

Monosynaptic reflex is one sensory and one motor neuron.
Knee-jerk reflex is an example (it has no interneuron) the sensory neuron directly synapses with the motor neuron.

4. So if Na+ channels are left open then Na will be in the cell and out of the cell equally, but the potassium channel is closed and the sodium potassium pump is still running. That would force all of the Potassium into the cell to be very positive right? Different scenario: And if the potassium channels were open and sodium ones are closed then the pump would cause all the sodium out of the cell. Would the cell reach -70 or would the sodium come back into the cell to stabalize the negative charge? This is only a hypothetical situation.


5. Nodes of Ranvier, I know they allow us to use less ATP on the pumps by minimizing the area, but how does that work out? Wouldn't the areas that are myelinated also need to repolarized, hence using the same amount of ATP?

the myelinated areas do not get polarized because they are made of lipid (insulator). I think they use less ATP because the AP jumps from node to node

6. Spinal cord controls our primitive processes? All of them?
spinal cord functions:

1. it's a reflex center
2.sends motor info from brain to muscle
3. sends info from somatic and autonomic systems to the brain

 

[doc3232]

Thanks people
More questions on the way

 

[jay47]

1. Acetylcholine is a neurotransmitter that is always excitatory and also lets Na+ into the postsynaptic thread? So does that mean neuron cell to neuron cell synapses would be the same as neuromuscular junctions or at least similar in some cases?

Okay, just took my physiology final and made a 98, let me help you here....
I wouldn't say that acetylcholine is always excitatory. For example, ACh is always used in parasympathetic innervation (e.g. the vagus nerve, which slows heart rate and constricts bronchioles, not exactly excitatory) The neuromuscular junction is different for several reasons:
1. There is more (relative to nerve to nerve connections) ACh released, so almost all nerve conduction to muscle contraction impulses are 1:1 ratio. Nerves in the brain must rely are EPSP's to summate and cause an Action Potential to travel down the neuron.
2. The neuromuscular junction also has nicotinic receptors on the postsynaptic membrane, while the receptors may vary in the brain due to different neurotransmitters being used.
As a whole, the overall "mechanism" of transmission is the same, but the specifics, such as receptor types, level of stimulation, and channel types are different.
2. How does temporal summation and spatial summation work? I partially understood spatial summation, but I didn't understand temporal summation.

Spacial Summation: graded potentials arrive from two DIFFERENT neurons to excite the postsynaptic nerve to threshold.
Temporal Summation: graded potentials are transmitted rapidly, that is at a higher rate, FROM THE SAME NEURON to excite the postsynaptic neuron to threshold.

3. Monosynaptic reflex arc is made up of only 2 neurons and 1 synapse? The only examples in my book had a sensory neuron that ran through the spinal cord and ran through an interneuron (that was in the spinal cord). What is an example of one and how does it work?

This should be incorrect, there should not be an "interneuron"; the afferent nerve should DIRECTLY branch onto the efferent nerve, with only two different nerves [as you do state] involved. The afferent nerve is a muscle spindle fiber while the efferent nerve is an alpha motor neuron. This is a great picture: blue is afferent nerve and red is efferent nerve-http://instruct.uwo.ca/anatomy/530/stretchr.gif

4. So if Na+ channels are left open then Na will be in the cell and out of the cell equally, but the potassium channel is closed and the sodium potassium pump is still running. That would force all of the Potassium into the cell to be very positive right? Different scenario: And if the potassium channels were open and sodium ones are closed then the pump would cause all the sodium out of the cell. Would the cell reach -70 or would the sodium come back into the cell to stabalize the negative charge? This is only a hypothetical situation.

Strange question, and I'm not sure that your fundamental understanding of this concept is complete, but in this case the cell would simply reach a resting membrane potential of -90, the potential set by potassium (assuming it's only permeable to potassium and not to sodium). It's complicated, so don't worry about this for the DAT; that's a physiology class question.

5. Nodes of Ranvier, I know they allow us to use less ATP on the pumps by minimizing the area, but how does that work out? Wouldn't the areas that are myelinated also need to repolarized, hence using the same amount of ATP?

No, the conduction "jumps" from node to node by a process called saltatory conduction, skipping the other spaces. Myelin is a fatty substance, meaning it is a good insulator. The potential doesn't have to depolarize the spaces within the neuron, it skips them.

6. Spinal cord controls our primitive processes? All of them?

What primitive processes? If you mean by breathing, heart rate then no. The brainstem would collectively control most "primitive" processes. The medulla and pons control respiration through the phrenic nerves, not even in the spinal cord, which explains why you can still breathe when you break your neck. The spinal cord is the pathway through which almost all information flows. Stretch reflexes occur only in the spinal cord, but I think that's about it.

Hope I've helped; I know that someone else responded before me, but I didn't even read their responses, so you can see how they agree/disagree with mine. PM me if you need anything, really: I read 3/4 of the book, twice.

Thanks, Jay

 

[jay47]

Im pretty sure acetycholine is both excitatory and inhibitory. It is excitatory in the neuromuscular junction and inhibitory everywhere else.

Pretty good assumption, but generalizations like this are too broad. It all depends on what you call "excitatory" vs. "inhibitory", which may vary on a case by case and nerve by nerve basis.

 

[doc3232]

Thanks Jay, you were ab big help, what are stretch reflexes? like the quadriceps/hamstring example is most books?

 

[Mrbubbles]

Thanks Jay, you were ab big help, what are stretch reflexes? like the quadriceps/hamstring example is most books?

OMG! i think i just threw up in my mouth. understand concepts, not details.

get an overview of BIG pictures (circulatory system, mucuskeleton (whatever it's called), respiratory etc)....

and how they work together if u wanna get more indepth...
use this time to do practice problems instead of making up questions. I guarantee u that the ACH question will come in the form of "Ach is a neurotransmitter associated with: a) parasymp b) sympathetic nervous system ..etc etc...

simple stuff.! and some diagrams just to piss u off.

 

[doc3232]

OMG! i think i just threw up in my mouth. understand concepts, not details.

get an overview of BIG pictures (circulatory system, mucuskeleton (whatever it's called), respiratory etc)....

and how they work together if u wanna get more indepth...
use this time to do practice problems instead of making up questions. I guarantee u that the ACH question will come in the form of "Ach is a neurotransmitter associated with: a) parasymp b) sympathetic nervous system ..etc etc...

simple stuff.! and some diagrams just to piss u off.

hahaha, ok I get it.

 

[Neuro178]

So as you can see it is the official one...

1. Acetylcholine is a neurotransmitter that is always excitatory and also lets Na+ into the postsynaptic thread? So does that mean neuron cell to neuron cell synapses would be the same as neuromuscular junctions or at least similar in some cases?

2. How does temporal summation and spatial summation work? I partially understood spatial summation, but I didn't understand temporal summation.

3. Monosynaptic reflex arc is made up of only 2 neurons and 1 synapse? The only examples in my book had a sensory neuron that ran through the spinal cord and ran through an interneuron (that was in the spinal cord). What is an example of one and how does it work?

4. So if Na+ channels are left open then Na will be in the cell and out of the cell equally, but the potassium channel is closed and the sodium potassium pump is still running. That would force all of the Potassium into the cell to be very positive right? Different scenario: And if the potassium channels were open and sodium ones are closed then the pump would cause all the sodium out of the cell. Would the cell reach -70 or would the sodium come back into the cell to stabalize the negative charge? This is only a hypothetical situation.

5. Nodes of Ranvier, I know they allow us to use less ATP on the pumps by minimizing the area, but how does that work out? Wouldn't the areas that are myelinated also need to repolarized, hence using the same amount of ATP?

6. Spinal cord controls our primitive processes? All of them?

So. That took a while to write.

Thanks in advance for your help

Okay.. hopefully my neuro major and neuroscience research can help here... haha

1. Don't be caught by excitatory/inhibitory neurotransmitters. The receptors themselves are excitatory/inhibitory. My neuro prof always told us that is a common mistake made by textbook writers. I do believe ACh can be received by inhibitory receptors.

2. Jay47 explained it well. Look up pictures for a visual explanation.

3. It goes: sensory neuron - interneuron - motor neuron. Monosynapse = one synapse. Although, where is the synapse? I looked back through my neuro notes and my prof wasn't very clear on this...

4. Might want to review the main concept of an action potential. Sodium channels open, sodium rushes in, cell is depolarized (very positive). Then during the repolarization/refractory period, sodium channels close, the potassium channels open, and potassium leaves the cell. This repolarizes the cell, putting its membrane potential back in the negative. Then we have hyperpolarization, etc. I'm not sure I understood your exact questions, but that is the basic idea.

5. Jay47 got this one too. Myelin allows for saltatory (faster) conduction of APs, and the nodes are the breaks/gaps in the myelin.

6. The pons/medulla/hypothalamus control the main "primitive" processes, such as respiration, thirst, hunger, etc.

Hope this helped!