Neurons and Neurotransmitters

What are neurotransmitters?

Neurotransmitters are chemical messengers that enable the communication of nervous cells, neurons, in the central and peripheral nervous systems. Neurotransmitters either potentiate or prevent the "firing," or action potentials, of neurons farther down the line, and are therefore called excitatory or inhibitory respectively. In the human brain, this aspect of function regulates the flow of information across complex networks of neurons associated with emotional, cognitive, and behavioral experiences.

First of all, what exactly is a neuron?

A neuron consists of three main parts: dendrites, a cell body, an axon, and axon terminals. Dendrites are numerous and extend from a cell body like branches. They receive neurotransmitters. The longer single axon extends from the cell body and allows the positive charge to travel down its length. At the axon's end is the axon terminal, from which neurotransmitters are released. The cell body contains the nucleus and is where the proteins are produced.

How do neurotransmitters work?

A neuron, like all cells of the body, normally has a small electric charge to it of about -70mV, with the inside of the neuron being negative compared to the outside. This is due to the concentration of negatively charged proteins inside the cell being larger than the concentration of positively charged sodium ions outside the cell. When a neurotransmitter is released from the axon terminal of a previous neuron, it binds to the dendrites of the next one. Here it attaches itself and causes a flow of ions through the membrane of the dendrite. If the neurotransmitter is excitatory, it allows sodium to flow into the dendrites and this positive charge travels down the axon causing more neurotransmitter to be released from the axon terminal, and so on, until an effect occurs, such as a feeling of pain, or the movement of an arm, or the memory of a friend. If the neurotransmitter is inhibitory, it does not allow for the passage of sodium through the dendrite membrane and consequently no neurotransmitter is released and no effect is seen.

Where do neurotransmitters work?

The central nervous system consists of the neurons of the brain and spinal cord. The peripheral nervous system consists of the neurons in the body and head that carry information to and from the central nervous system. For example, when you step on a nail a peripheral nerve picks up the sensation and sends it to a neuron in the spinal cord which sends it to a neuron in the brain which interprets the message as "ouch!"

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