Neurotransmitters are “are chemicals that are used to relay, amplify and modulate electrical signals between a neuron and another cell” (Wikipedia, 2006). They help to convey information through the movement of chemicals through the synapse. Released at the presynaptic nerve terminal, they arrive at the synapse to be received by the neuron at the place named receptor. When the receptor is activated, the next step is “either depolarization (an excitatory postsynaptic potential) or hyperpolarization (an inhibitory postsynaptic potential)” (Washington University, n.d.). When the substance has had its effect, it is absorbed into the enzyme through the process called uptake or reuptake. In this way, the neurotransmitter is inactivated.
By exciting or inhibiting neurons in various parts of the body, neurotransmitters have impact on moods, memory, and well being of the individual. They are synthesized within the cell body of the neuron and then go down the axon within vesicles when they “fuse” with the membrane of the axon terminal, spilling the neurotransmitter into the synaptic cleft” (Washington University, n.d.).
There are a variety of neurotransmitters responsible for different functions in the sympathetic and parasympathetic nervous system and the brain. The most important neurotransmitters include dopamine, serotonin, acetylcholine, histamine, norepinephrine, epinephrine, and others. Thus, “serotonin is released specifically by cells in the brainstem, in an area called the raphe nuclei” (Wikipedia, 2006). Serotonin is involved in sleep disorders, schizophrenia, and emotional mood swings. Acting inside an area in the middle section of the brain, this substance is also found in the cerebral cortex and the spinal cord. In addition to the brain, it also affects the digestive and the cardiovascular systems. Dopamine helps to regulate the brain’s reward mechanism and regulates motion.
These actions performed by neurotransmitters are often targeted by drug actions. Cocaine acts to prevent the uptake of dopamine; as a result, dopamine longer stays in the synapse. The same action is performed by anti-depressants that fall into the class of serotonin reuptake inhibitors. An increase in dopamine levels contributes to the improvement in moods in human beings. Illness can be in caused by malfunction of neurotransmitter cycles. Thus, Parkinson’s disease is “related to failure of dopaminergic cells in deep-brain nuclei, for example the substantia nigra” (Wikipedia, 2006).
The above demonstrates that human behavior is guided to a great degree by the biological functioning of the human body. An increased or decreased level of a certain neurotransmitter can have a serious effect on the human brain and behavior. Serotonin, for example, is involved in anxiety disorders, and various types of depressions. Thus, an understanding of biological mechanisms and various substances involved in their functioning is crucial for the realization of inner motives of human behavior. While human conduct is too complex to be reduced to the action of substances, it is nevertheless in direct dependence on the processes in the body. This means that study of biology is of great importance to the understanding of human behavior, and study of neurotransmitters is of special importance to this endeavor.
Washington University. (n.d.). Neurotransmitters and Neuroactive Peptides. Retrieved July 22, 2006, from http://faculty.washington.edu/chudler/chnt1.html
Wikipedia. (2006). Neurotransmitter. Retrieved July 22, 2006, from http://en.wikipedia.org/wiki/Neurotransmitter
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