What is a neurotransmitter?
Neurotransmitters are chemical messengers that help relay information throughout the body. They transmit information through nerve cells called neurons. In its most basic form a neuron has two ends (although either can have multiple branches): an axon and a dendrite. A neuron communicates with other neurons by sending neurotransmitters from its axon to a dendrite of another neuron. The space between the axon and the dendrite is called a synapse; this is the space across which a neurotransmitter must cross.
Neurotransmitters are stored in the axon (or pre-synaptic neuron) in little packages called synaptic vesicles. They are released if an appropriate charge is sent down the axon. Once released, they cross the synapse to dock with receptors on the dendrite of another neuron (often called the post-synaptic neuron). If enough neurotransmitters dock with the receptors, a signal is sent down that neuron and the message continues on. However, if not enough neurotransmitter docks with the receptor, then the message stops.
It’s a lot like electricity going through a wire. Turning up the voltage will cause more electricity to go through the wire. In our case, the neurotransmitters act like electricity – if we have enough electricity, the lights will come on and things will run smoothly. If we don’t have enough electricity, things just don’t work like they should.
Either way, once the neurotransmitter is released from the receptor, it is either taken back up into the synaptic vesicle of the axon by a neurotransmitter reuptake pump/transporter or it is destroyed by enzymes that are present in the synapse.
If the neurotransmitters are taken back up into the pre-synaptic neuron via the reuptake transporters, they are protected and can be used again. However, if the transporters are blocked (as is the case with selective serotonin reuptake inhibitors and other medications), the neurotransmitters are eventually destroyed and cleared from the system by enzymes.
Most neurotransmitters are classified in one of two types – inhibitory and excitatory. Inhibitory neurotransmitters slow down the flow of information by calming and reducing the activity of neurons; they help to bring balance to the body. Excitatory neurotransmitters generally increase the flow of information. It is the balance between the inhibitory and excitatory neurotransmitters that has the greatest effect on your body functions.