In all vertebrates and most invertebrates, the brain is the central part of the nervous system. This centralizes all functions of the nervous system. There are however, some living things like the starfish that have no brain hence demonstrate a decentralized nervous system. In addition, other living things like sponges have no brain and nervous systems. For vertebrates, the brain is located in the head and at close proximity senses like taste, sight, smell, hearing, and balance.
The human brain is made up of billions of neurons and the quantity is dependent on gender and age. These neurons are normally referred to as chemical messengers or neurotransmitters, whose main work is communication means between different brains cells which can influence mood, physical occurrences, and aggression among others. Neurotransmitters are then classified into three: Peptide, Biogenic amine, and amino acid neurotransmitters. The work of neurotransmitters is made possible by a firm jelly called the Cerebrospinal Fluid (CSF) secreted by the choroids plexus. This paper intends to discuss the six major neurotransmitters of the human brain their functions and impact on medical diseases.
The major neurotransmitters, as stated by Keamey and Trull (2010), of the brain are glutamic acid and Gamma-amino butyric acid (GABA) which are the two main amino acid neurotransmitters. The reason why the two are the most important neurotransmitter is because they are excitory (Glutamate) or inhibitory (the GABA). The other four include Serotonin, Norepinephrine, Dopamine, and Acetylcholine.
The most common neurotransmitter in the brain is Glutamate which is an excitory neurotransmitter (Keamey and Trull 2010 P 26). This neurotransmitter is mostly associated with learning and memory. Too much glutamate can accumulate in the brain in the effect of a disease like stroke or Alzheimer’s disease of the elderly which is associated with memory loss. This excess glutamate affects the brain by causing damage or death of the affected brain cells due to resulting conditions called excitotoxity.
According to Keamey and Trull (2010 P 26), the second major brain neurotransmitter is called GABA which is an inhibitory courier functioning in the negative response system for the purpose of preventing a signal from being transmitted to another cell. GABA’s main function is in the regulation of mood and particularly arousal, anxiety and behavior through the balancing of the brain’s excitation. For this reason, GABA is very important in reducing anxiety disorders and hence a source of relaxation.
Serotonin is a monoamine neurotransmitter produced and found in the gastrointestinal track and the central nervous system of humans. Serotonin is associated with roles of regulating the digestive system and appetite, and coordinate muscular responses such to modulate mood, anxiety, sleep, and sexuality, and processing of information. One mental disorder associated with Serotonin is the panic disorders which treated with the use of Serotonin Reuptake inhibitors (SSRIs) (Masters and Mc Guire 1994).
Dopamine is associated with novelty such as looking for friendliness, enjoyment, incentive, harmonization and motor movement. Parkinson’s disease of the brain and Schizophrenia are associated with the dysfunction of the Dopamine system (Kretschmann and Weinrich 2004).
According to Keamey and Trull (2010), acetylcholine is the neurotransmitter responsible for the motor behavior, arousal, reward, learning and memory. Like the Glutamate, acetylcholine is associated with diseases of the brains in the likes of Dementias, stroke and Alzheimer’s disease of the elderly that is associated with memory loss.
Finally, is the Neropinephrine neurotransmitter that is associated with modulation of arousals, mood, behavior and sleep. This is the stress hormone in the brain and is found in the Amygdala part of the brain which controls both attention and responses. The other function is the drug for low blood pressures as its rises the blood pressure (Kretschmann and Weinrich 2004).
Keamey C. and Trull T., (2010). Abnormal Psychology and Life: A Dimensional Approach. Cengage Learning. Canada: CA.
Kretschmann H. and Weinrich W., (2004).Cranial Neuroimaging and Clinical Neuroanatomy: Atlas of MR imaging and Computed Tomology. George Theime Verlag. New York: USA.
Masters R. and Mc Guire M. T., (1994). Neurotransmitter revolution: Serotonin, social behavior, and the law. Illinois University. United States of America: USA