Neurotransmitters play a vital role in controlling the functioning of the brain. In line with this, there are various kinds of neurotransmitters that have been identified so far. These are categorized in three groups namely; amino acids (primarily glutamic acid, GABA, aspartic acid & glycine), peptides (vasopressin, somatostatin, neurtensin, etc) and monoamines (neropinephrine, dopamine & serotonin). This paper will look at six major neurotransmitters; their function, their impact on medical disease and mental illness. These are; dopamine, serotonin, acetylcholine, noradrenaline, glutamate, and endorphins.
To begin with, dopamine plays a vital role in enhancing the brain functioning of human beings. It is important to note that dopamine is responsible for providing physical motivation since it manages the levels of arousal in most parts of the brain. As a result of this, low levels of dopamine in the brain are associated with mental stasis. In reference to Nevid (2008), irregularities in dopamine functioning in the brain may help explain the development of schizophrenia, a severe mental disorder characterized by symptoms as hallucinations and delusions as well as Parkinson's disease that is characterized by progressive loss of motor function, or physical movement (p.47).
Serotonin is another neurotransmitter that has been identified in the medical world. According to Nevid (2008), serotonin functions mostly as an inhibitory neurotransmitter; it helps regulate moods, feelings of satiation after eating, and sleep (p.48). Researches and studies that have been carried out in the past indicate that irregularities in the level of serotonin could result in depression. Furthermore, Nevid (2008) asserts that abnormalities in the activities of serotonin, a neurotransmitter involved in regulating feelings of satiaty, may prompt bulimic binges, which can be reduced by administering antidepressant drugs (p.300).
Acetylcholine (ACh) too is responsible for stimulating skeletal muscles to contract in response to voluntary commands since this neurotransmitter have an excitatory effect. In other words, acetylcholine play a vital in stimulating voluntary movements, without which the skeletal muscles would fail to contract as needed to facilitate these movements. Moreover, acetylcholine has been found to play a vital role in stimulating or rather controlling the beating of the heart. In reference to Nevid (2008), when receptors sites for ACh are blocked thus locking out ACh, one is affected by paralysis.
Noradrenaline on the other hand is responsible for concentration, alertness and attention. In this regard, research and studies that have been carried out in the past indicate that depression has been linked to low levels of noradrenaline. According to Webster (2001), although some studies show that noradrenaline inhibits neuronal firing it is general considered to increase behavioral activity and arousal. Notably, as mentioned above, low levels of noradrenaline could easily lead to depression.
Glutamate is generally an excitatory neurotransmitter. As such, it is important to understand that glutamate must be available in the right amount in the body. This is because very high amounts or very low amounts of glutamate are dangerous to the normal functioning of the brain. Schmidt & Reith (2005) affirms that glutamate is responsible for mood disorders among human beings.
Finally, endorphins are also neurotransmitters that play an important role in transmission of messages in the body of human beings. In line with this, endorphins were tasked with enhancing a sense of well-being in the body. As such, pain in the body can be dealt with when endorphins are released, especially during body workouts. In reference to Hemat (2007), endorphins are neurotransmitters produced in the brain that reduce pain and create feelings of happiness, vitality, and well-being. As such, they arguably form the first line of body defense against mental, emotional and physical stress. As such, low-levels of endorphins could cause an increase in physical, emotional and mental stress levels.