Question

10. Glutamate is an example of an excitatory amino acid neurotransmitter that acts via direct synaptic transmission when it is released from presynaptic neurons in the brain.

Which of the following is a mechanism by which an action potential is LEAST likely to occur in the associated postsynaptic neuron? Summation of ionic events

1. temporally from rapid stimulation of the presynaptic neurons that release glutamate

2. spatially from the glutamate-releasing neurons and other neurons releasing an excitatory neurotransmitter that acts via an indirect mechanism

3. spatially from the glutamate-releasing neurons and other neurons releasing the excitatory transmitter, aspartate

4. spatially from the neurons releasing glutamate and other neurons releasing the inhibitory transmitter, GABA

5. spatially from many postsynaptic neurons that release glutamate.

Answer 1

Answer will be.. Spatially from neurons releasing glutamate and other neurons releasing the inhibitory transmitter GABA.

Explanation::

As we know the glutamate amino acid is an example of excitatory neurotransmitter (NT) responsible for activation of reaction .It always release when gets a excitatory stimulus from the presynaptic terminal and binds with the specific receptor on the post synaptic cells. Normally Sodium ions channels are responsible for opening and release Na⁺ K⁺ ion after getting stimulus.In resting state Na ions present more at outside as compared to inside ,so more negative charge is inside as compare to outside,when excitatory stimulus occur due to NT the Na⁺ channel open and allow entry of Na⁺ inside the cells , which results into depolarisation of nerve membrane additionally responsible for threshold action potential .So glutamtate is responsible for depolarisation of neurons or excitatory postsynaptic potential..means reaching the action potential to threshold level.( For attaining threshold action potential sometimes many postsynaptic cleft require to release NT because one postsynaptic cleft release is not enough to reach that level)

On the contrary GABA is inhibitiory NT ,after getting Na⁺ channel open after some time K⁺ ions shows response and K⁺pumped out from the cell and able to close the Na influx .(k⁺ channel open causes hyperpolarization)....as a result voltage gated channel present on the synaptic cleft open which results into calcium channel opening ,helps to maintain the membrane potential and membrane will become hyperpolarised ..which means at that time action potential will below from the threshold and the activity will stop.Inhibitory NT response to chloride channel opening.(

So,Glutamate and GABA will respond opposite to each other,when cell needs activation glutamtate,Aspartate,and other excitatory neurotransmitter released from the brain cells and when it will be required to inhibit the action GABA NT will release.Both are working oppositely, one responses in depolarisation and in threshold action potential while other responses in hyperpolarization and below threshold action potential.

So ,on account of the question it will be least likely that excitatory and inhibitory neurotransmitters work at same response ,at a same time it will be either excitatory or inhibitiory action because both required different channel opening.