Question

Acetylcholine is

(a) Neural messenger

(b) Anti Stress hormone

(c) Chemical messenger

(d) Chemical transmitter

Answer 1

Hint: This communicates between the two neurons and between a neuron and a muscle. These do not participate in the transmission of nerve impulses at the electrical synapses.

Complete step by step answer:

Acetylcholine is a neural messenger. This is the neural messenger or neurotransmitter present in the preganglionic sympathetic and parasympathetic neurons. This is a type of excitatory neurotransmitter.

So, the correct answer is ‘Neural messenger’.

Additional information:

As a neural signal reaches the presynaptic membrane, Calcium channels get open up. Due to this, the membrane of synaptic vessels fuses with the plasma membrane of the synaptic knob. So this results in the release of neurotransmitters in the synaptic cleft.

These neurotransmitters bind to their specific receptors present on the postsynaptic membrane. Now the entry of ions generates the new potential. An increase in the Calcium ions leads to the binding of Calcium with the subunit of troponin on actin filaments and thus remove the active sites of myosin and facilitates muscle contraction.

Overall this Acetylcholine is released from the axon of the motor neuron, diffuses across the synapses, and binds to the receptors on the muscle cell, leading to contraction.

Note:

- Acetylcholine was the first neurotransmitter that is discovered by Otto Loewl, originally known as ‘Vagus stuff’.

- In the peripheral nervous system, it causes skeletal muscles to contract.

- Acetylcholine inhibits the action of the activation of the cholinergic system in the central nervous system.

- Acetylcholine is broken down by the enzyme called acetylcholinesterase which is already present in the synaptic cleft and terminates the action of the transmitter.