The function of neurotransmitters is the sending of signals from neurons to muscle fibers, glands, or to other neurons. These chemicals act in the body to regulate a variety of processes, including responses to stimuli and emotional states. Imbalances in the chemistry of the central nervous system can resort in disorders due to excessive or reduced levels of neurotransmitters. For example, some people with depression have an imbalance in the chemical serotonin which contributes to deep depressive moods. Studies on the function of neurotransmitters identify the different kinds of chemicals found in the body and how they work, which can be applied to medical treatment.
Neurons can interact through chemical or electrical synapses. Electrical synapses require a direct physical connection for signals to travel between a neuron and the target. Chemical synapses take the form of a small gap. Pouches known as vesicles squeeze out neurotransmitters, triggering a response in the target when they lock onto receptors. It can release the chemical when the response is over to allow the body to recycle it, which permits rapid recovery between nerve signals.
In the case of a synapse connecting two nerves, the neurotransmitters work to pass a signal on. They may excite or inhibit a neuron, moderating a response. For example, the neurotransmitter dopamine is involved in pleasure and reward in the brain. When people do something they enjoy, the brain releases more of this chemical, triggering a series of nerve responses that create a feeling of happiness. This regulation of neurological activity is an important part of the function of neurotransmitters.
Muscle fibers may be told to contract or relax by a neurotransmitter. This in turn can signal neighboring fibers to create a chain reaction. Another function of neurotransmitters can be seen at the glands, where these chemicals stimulate the production and release of hormones. For example, some people experiencing a flight or fight response typically develop a cascade of chemical reactions in their bodies, including the release of specific hormones in response to neurotransmitter signals.
When a disruption occurs, a patient can experience symptoms like poor motor coordination, hormone imbalances, or difficulty with cognition. Disorders involving the function of neurotransmitters may be treated with medications to restore the chemical balance. For instance, patients could take medications to slow the rate of reuptake, where the chemicals are absorbed for use in another signal; this increases the amount of neurotransmitters active at any given time.