Question

During synaptic transmission of nerve impulse, a neurotransmitter (P) is released from synaptic vesicles by the action of ions (Q) . Choose the correct P and Q.
(a) P = acetylcholine, Q = ${ Ca }^{ ++ }$
(b) P = acetylcholine, Q = ${ Na }^{ ++ }$
(c) P = GABA, Q = ${ Na }^{ + }$
(d) P = Cholinesterase, Q = ${ Ca }^{ ++ }$

Answer 1

Hint: There are neurotransmitters present in each synaptic vesicle which are involved in the transmission of nerve impulses across chemical synapses. These are exhibitory neurotransmitters. The neurotransmitter P has its agonist as nicotine and antagonist as atropine. The ions Q are abundant ions that take part in muscle contractions too.

Complete answer:
A nerve impulse is transmitted from one neuron to another through junctions called the synapse. A synapse is formed by the membrane of presynaptic neurons and postsynaptic neurons and may or may not contain a synaptic cleft. In chemical synapses, impulses are transmitted through neurotransmitters. For example, Acetylcholine. The cytoplasm of the synaptic node contains tiny, round sacs called synaptic vesicles. These synaptic vesicles contain 10,000 molecules of neurotransmitters that are chemicals that are involved in the transmission of nerve impulses across chemical synapses.
When the depolarization reaches the pre- synaptic membrane, calcium channels concentrated at the synapse open up. Due to the opening of calcium channels, ${ Ca }^{ ++ }$ diffuse inside the cytoplasm of the synaptic knob from the extracellular fluid. The calcium ion in some way stimulates the movement of synaptic vesicles towards the pre- synaptic membrane. Therefore, resulting in the rupture of synaptic vesicles and the release of Acetylcholine.
So, the answer is, ‘P = acetylcholine, Q = ${ Ca }^{ ++ }$ ‘

Note: - Neurotransmitters do not participate in the transmission of nerve impulses at electrical synapses. - There are two types of neurotransmitters: Excitatory neurotransmitters, for example, Acetylcholine, Epinephrine, Norepinephrine, and Inhibitory neurotransmitters, for example, Dopamine, Serotonin, and GABA. - Acetylcholinesterase is present in the muscle cells or post-synaptic neurons. It breaks down acetylcholine into acetate and choline and terminates the action of the transmitter.