Neurotransmitters
Neurotransmitters involve materials which neurons use to send messages between one another and their target tissues through the process of neurotransmission. They are released from the nerve ending to the synaptic cleft where they bind to receptor proteins of the target tissues, which are inhibited, excited and modified functionally in different ways. The human nervous system constitutes several neurotransmitters where the most important ones include serotonin, Norepinephrine, Histamine, Gamma-aminobutyric acid (GABA), dopamine, glutamate and acetylcholine.
Neurotransmitters can also be defined as the chemical envoy that increases, balances and carries signals between nerve cells and other neurons in the body. The neurotransmitters continuously work to keep the brain functioning and manages everything our body does. The principal purpose of neurotransmitters is that they perform as signalling molecules that permit neurotransmission. They ensure the transmission of signals from one nerve cell to another or one gland cell to another.
Serotonin is one of the vital chemical neurotransmitters in the human body. Its majorly found in the digestive system although it’s located in the central nervous system and the blood platelets. The neurotransmitter ensures that it controls social behaviour, mood, digestion, appetite, sexual desire and function, memory and sleep. This results in serotonin being linked to depression. Serotonin impacts every body part from emotions to motor skills hence considered as attitude stabilizer. This chemical helps the body with sleeping, eating and digestion. Serotonin helps in carrying out the following in the body. Firstly, it regulates mood. The serotonin found in the brain helps in modifying happiness, anxiety and mood. Inadequate levels of serotonin in the body result in depression, while high amounts majorly brought through medication will lead to decreased arousal. Secondly, the neurotransmitter helps in controlling sleep. It’s capable of exciting the brain parts that regulates waking and sleep. For one to stay awake or asleep, its mainly determined by what area is enthused and which serotonin receptor is used. Thirdly, this neurotransmitter helps in blood clotting where the platelets release serotonin to heal the cuts. Lastly, the levels of serotonin in the body determine the sexual function. The high standards result in decreased libido, while low levels lead to an increased desire.
Some of the other neurotransmitters to be discussed include Norepinephrine, histamine and acetylcholine. Norepinephrine is also referred to as noradrenaline that is confined mainly from the ends of sympathetic nerve fibres. It primarily increases the force of contraction of skeletal muscle and the power of contraction of the heart. These actions are animated to the fight response where the body is always ready to act to the external threats. The Norepinephrine in the blood vessels triggers vasoconstriction of blood vessels, which increases blood pressure hence increasing the amount of blood from the heart. It also helps in increasing the levels of fatty acids circulating in the body and the level of glucose in the blood.
Histamine is a carbon-based nitrogenous compound tangled in minor immune responses and modifying physiological function in the gut. Histamine is a neurotransmitter help to control the wake-sleep cycle and may result in increased permeability of the blood-brain barrier. It’s also involved in influencing neuroendocrine control such as biological rhythms, reproduction, behavioural state, thermoregulation and energy metabolism. The neurotransmitter is also involved in neurocognitive cognition, where high levels of histamine affect thyroid function.
The third neurotransmitter is acetylcholine. It is the most copious neurotransmitter and the first neurotransmitter that scientists discovered. This is the chief neurotransmitter of the parasympathetic nervous system that widens blood vessels, contracts smooth muscles, reduces heart rate and upsurges body secretions. Acetylcholine, functions in the central nervous system and the peripheral nervous system as both inhibitor and activator. It ensures that it prevents initiation of the cholinergic system in the central nervous system while causing contraction of skeletal muscles in the peripheral nervous system. It also plays a vital role in signalling sensation of pain, muscle movement, rapid eye movement sleep cycles and memory and learning formation.
Stroke
Stroke affects several areas of the brain, including cerebellum, brain stem, limbic system and the cerebrum. A keystroke affecting the brain stem is usually lethal since this part help in life-supporting functions such as heart rate, breathing, digestion and blood pressure. When an individual can speak but has problems in understanding other the likely disorder affecting the individual is Wernicke’s Aphasia. This disorder impairs both understandings of language and expression. The side of the brain that is affected by Wernicke’s Aphasia disorder is the left middle side of the brain. A neurologist recognizes an individual with this disorder by typically involving individual with the disease to answer questions, follow commands converse and name objects. If Aphasia is suspected, the patient is referred to a speech-language pathologist who examines the ability of the person to speak, read and understand.
The cerebral hemisphere has two hemispheres, namely the right and the left hemisphere. These hemispheres are divided into four lobes: parietal, occipital, temporal and frontal.
The frontal lobe is located in the frontward part of the brain outspreading back to the central sulcus. If the lobe is affected, it affects language, motor control, emotion and reasoning. For example, one can do routine tasks like going to market to do shopping but can’t communicate verbally if the situation calls. An excellent example of a known case of frontal lobe damage is of Phineas Gage.
The parietal lobe is located closely behind the frontal lobe. The lobe is involved in processing info from body senses which include pain, temperature and touch. If the lobe is damaged, the individual is unable to sense any feeling concerned with touch pain and temperature.
The temporal lobe is located on the head side. When an individual has a damaged temporal lobe, the Wernicke’s area and the auditory cortex are damaged. This result in loss of emotion, some language aspects, memory and hearing.
The occipital lobe is located at the back of the brain. This is where the primary visual cortex is located, which is retinotopically arranged. If the lobe is damaged, an individual is unable to interpret the received pictorial information.
Imaging techniques
Some of the brain imaging techniques include Magnetic resonance imaging (MRI), Positron emission tomography (PET) and electroencephalography (EEG). The PET uses some amounts of transitory radioactive materials to record useful procedures in the brain. It is used to measure the sugar levels in the brain of a patient. Radioactive isotopes are injected to the blood of the patient and the brain parts with the tracer is directed to transport oxygen. This, therefore, creates visible spots which are taken to make brain image while performing a certain task. The MRI is the neural imaging mostly used in psychology to align spinning atomic nuclei. The patients under this technique have to hold for long periods in a noisy. This technique is used widely to study psychological phenomena, including telling lies activities. The last brain imaging technique is the EEG which is used to illustrate brain activity in some emotional states such as drowsiness and alertness. The EEG is prepared by placing electrodes on the face and scalp. This is determined by person state where its main disadvantage is that electric conductivity may vary from person to person over time where it’s sometimes unclear where exactly which area of the brain is releasing the signal.
References
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Barth, M., Breuer, F., Koopmans, P. J., Norris, D. G., & Poser, B. A. (2016). Simultaneous multislice (SMS) imaging techniques. Magnetic resonance in medicine, 75(1), 63-81.