The function of a neuron depends on the type of neuron, each having its own function. The first neuron is the interneuron or relay neuron (white and green). The job of this nerve cell is to communicate with the sensory and motor neuron. With the sensory neuron (black) the function of this nerve cell is to convert external stimuli from the environment into internal electrical impulses which are sent to the brain. From here the interneurons in the brain make a decision, finally sending impulses to the motor neurons (pink and green) to make a certain motion. This process can be demonstrated using a coffee shop as an example. You are at a coffee shop and you are waiting for your order. Using your sensory neurons, you see your drink is finished being made and the barista hands you the drink, your sight enables you to sense this. You make a decision of what to do with the coffee with you interneurons, lastly you pick up the coffee with your hands after your brain makes the decision to do so after sending impulses through your motor neurons.
Action potential is an electrochemical signal that briefly travels throughout the axon. This is caused by positive sodium ions and negative potassium ions making movement within the axon. In polarization of action potential, it is constant with positive ions on the outside of the axon and negative ions on the inside. In depolarization, the positive ion enter the axon through channels in the membrane. Once entered a new channel opens for the positive potassium ions to leave the axon. This process is called repolarization.
Once the action potential (AP) reaches the end of the neuron’s axon, synapse occurs. A signal is sent to from one neuron to another. This signal travels from the axon of one neuron to the dendrite of the neuron that is receiving the signal. The synaptic vesicles in the axon produce neurotransmitters (NT) which are then released into the synaptic gap. This is when the released NT bind with the receptors on the dendrites of the receiving neuron. These NT can either stimulates the AP by being excitatory or can repress the AP by being inhibitory, ultimately this is decided by the receptor. If the NT is glutamate it would causes an excitatory reaction and stimulate the AP where as if the NT is GABA it would cause the opposite and repress the AP with an inhibitory reaction.
synapse photo link:https://www.quora.com/What-happens-at-synapse