If a neuron was stimulated simultaneously at both ends, the action potential generated in the middle would effectively cancel out due to the opposing electrical currents flowing towards each other. This phenomenon is known as antidromic collision and may prevent the neuron from conducting signals efficiently.
The actional potential would not reach the axon terminals.
Neurotransmitters send signals from neuron to neuron
That would be an interneuron otherwise known as an associative neuron.
A two-neuron reflex typically involves a sensory neuron carrying information from a sensory receptor to the spinal cord, where it synapses with an interneuron. The interneuron then synapses with a motor neuron that carries the response signal to an effector organ, such as a muscle or gland. In this pathway, a third neuron would not typically be involved in a two-neuron reflex.
Movement
It depends on what you mean by 'main'. The AXON is the part which CONVEYS the neural impulse, which could be thought of as the main FUNCTION of the neuron. But the DENDRITES are the parts which assess whether the neuron has been stimulated enough to fire the axon, which is another fundamental function of some neurons. And the BODY (soma) of the neuron is very much a 'main' part of the neuron, because without it the neuron would die.
The neural activity progresses as if it were a wave (the effect moves but the nerve, of course does not). As the wave progresses it depolarizes the nerve surface, opens Na+ channels and activates the nerve surface as it goes forward. One effect of the firing however is that the Na+ channels inactivate and enter a refractory period in which they will not reopen. This essential drives the propagation wave in one direction only. If the nerve were to be simultaneously stimulated at both ends the two waves would meet and then activity would cease. Neither wave would be able to overcome the refractory membrane that the other wave had passed over.
If a motor neuron in the body were stimulated by an electrode placed about midway along the length of the axon, the action potential would be generated and propagate both towards the cell body and towards the axon terminals. The direction of the action potential propagation is determined by the all-or-none principle, meaning that once initiated, the action potential will travel the length of the axon in both directions.
The actional potential would not reach the axon terminals.
if neurons didn't have myelin sheath then the transmission of nerve impulses is slowed or stopped
The cell membrane becomes more permeable to the sodium potassium ions.
The cell will depolarise
Nervous impulses travel along neurons through a process called action potential, which occurs when a neuron is stimulated by an external signal. This stimulation causes sodium ions to flow into the neuron, leading to a rapid change in electrical charge that propagates along the axon to the synapse. At the synapse, neurotransmitters are released to transmit the signal to the next neuron. A simple diagram would illustrate a neuron with labeled parts: dendrites, cell body, axon, and synaptic terminal, showing the direction of impulse travel.
Motor neuron
If a neuron is not sending out an impulse or signal, this means the neuron is at rest. Neurons send signals electrochemically.
neurotransmitters send signals from neuron to neuron
Blocking the chemically gated sodium channel in the postsynaptic membrane would prevent sodium ions from entering the neuron, hindering depolarization and transmission of the signal. This would effectively inhibit the neuron from responding to neurotransmitters released by the presynaptic neuron, leading to a disruption in neuronal communication and a potential loss of function in the neural circuit.