Question

Briefly explain synaptic activity following the release of neurotransmitter into the synaptic cleft. Include ionotropic and metabotropic receptors, and reuptake.

Answer 1

When an impulse is formed in the synaptic region so as to control a particular function the impulses are transmitted through the neurons. When neurons conduct an impulse the resting membrane potential is altered. The testing membrane potential in the neurone is a negative value creating more sodium ion concentration in the outside than inside. Soon the impulse teach the neuron the Na+ ions moves in and K+ ions moves out creating a positive potential in the particular part. Now the impulse is getting transferred to the next region through this process. At last the impulse teach the synaptic cleft. Here the impulse is transmitted by the chemical mechanism. When the impulse teach the synaptic cleft there activated the voltage based calcium channel allowing more Ca2+ influx making the vessicles filled with the neurotransmitter usually acetylcholine to move towards the presynaptic membrane. The vessicles fuse with the presynaptic membrane making the release of the neurotransmitter to the synaptic cleft. The neurotransmitter acts on the specialised receptors in the motor end plate on the post synaptic membrane. The neutramitter action on there receptors can be described on its action in the inotropic and metabotropic receptors. The inotropic receptor is the ligand gated receptor. Here the acetylcholine binds to the receptor and thus making the change in the shape of ion channels making them open. Now more Na+ reaches inside the cell thus changing the cell membrane potential. Thus the impulse is transferred to the next neurone. In case of metabotropic receptor. The metabotropic receptor use a second messenger to a the impulse. The G protein coupled receptor is one among them. The binding of the acetylcholine to the receptor activates the G protein. Thus GTP is formed. Then the alpha subunit acts on the Adenyl cyclase and activates the cAMP. This thus leads to the opening of the associated ion channels. The opening cause the Na+ to move inside and K+ to move outside making the cell potential to be positive and thus impulse is transferred. After that the acetylcholinesterase is released to the cleft making the neurotransmitter degrade. The degradation of the neurotransmitter ends the transfer of the nerve potential. Then the Na+/K+ ATP ase pump acts by the pumping the Na+ out of the cell and making the membrane potential back to the negative resting membrane potential. This done by hydrolysis reaction of the ATP to the ADP and thus making these pumps active.