In the human body, the brain is the most complex and unique organ. The reason why the brain is so unlike the other organs is because of its tangible and intangible processes. Other organs have a physiological basis for their processes and thus have certain quantifiable parameters. The brain, not only has neurobiological processes at work, but also cognitive processes. Consciousness is an abstraction, which is very real but is not directly measurable by scientific methods.
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Emotions, memories, intuition are other manifestations of the workings of the brain which are not directly calculable through some neurobiological areas that have been identified by doctors and researchers. The entire process of the brain and its relation to the human nervous system requires a holistic treatment which is being attempted by the medical and research fraternity the world over. It has also included specialists from the fields of psychology and philosophy and thus what may have seemed as just another human organ is proving to be a frontier yet to be completely explored by man. This essay aims to outline the relationship between the brain, the nervous system, and the larger context of its working in relation to the other parts of the human body.
Cell/ Tissue/Organ/ System
Any explanation of a living organism has to necessarily start with the organization structure best exemplified by the Cell/Tissue/Organ/System methodology. The cell is the basic unit of a living organism. A group of cells forms a tissue, a group of tissues form an organ, a group of organs working to perform a bodily function forms a system and all organ systems working in concert finally give rise to the living organism as it is known. This methodology applies to the brain and the nervous system also.
The basic unit of the brain is the neuron which are special cells configured by nature to communicate information. Information is conveyed from neuron to neuron in the form of electrical signals by small gaps between them called synaptic clefts. The brain has billions of these neurons. Just as a computer logic of binary digits of yes or no, the neurons are either active or at rest. The similarity with such an analogy stops at this level because unlike a computer that finds answers based on stored information, the brain processes information not only with stored information but also with relational methods which are not easily defined and as yet difficult to replicate artificially.
Billions of neurons make parts of the brain tissue which also contains supporting cells and special formations forming important sub-organs within the main organ called the brain. The brain is a subset of the human nervous system but plays a central role in the overall functioning of the human body.
Anatomical and Physiological Mechanisms of the Brain and the Nervous System
The organization of the nervous system is best explained by dividing it into the Central Nervous System and the Peripheral Nervous System. The Central nervous system is said to comprise the brain and the spinal cord. The Peripheral nervous system comprises the sensory nerves and the motor nerves. Information is stored and processed in the brain, while the spinal cord acts as a pathway for that information. The sensory nerves of the peripheral nervous system bring information from different parts of the body to the central nervous system while the motor nerves send information away from the central nervous system.
Motor nerves that provide stimulation to the skeletal muscles like your arms are called somatic nerves while those that control the stimulation of smooth or cardiac muscles are called autonomic nerves. The somatic motor system acts in a controlled manner while the autonomic motor system has a further subdivision of sympathetic and parasympathetic fibers. The importance of these two subsystems lies in the effect they have on the maintenance of Homeostasis.
The Role of Brain and the Nervous System in Maintaining Homeostasis
The survival of a human organism depends on its ability to maintain normal internal balance which is called homeostasis. There are a total of eleven organ systems in the human body which must function within a normal range to ensure the survival of the organism. These eleven organ systems are the muscular system, the skin or integument system, digestive system, respiratory system, circulatory system, lymphatic system, nervous system, endocrine system, urogenital and reproductory systems, and the excretory system. The autonomic motor system as the name suggests controls automatic movements such as heartbeats, breathing, and control of involuntary muscle action.
The brain, together with the larger nervous system is crucial in maintaining homeostasis. All voluntary and involuntary processes in the human body and the associated organ systems have their origin in the brain. The brain has been divided into hindbrain, midbrain, and forebrain. Each division has further subdivisions and specific areas which control certain bodily functions and provides the necessary triggers for the various organs systems of the body. According to Levinthal (1990), the Medulla is located in the lower part of the hindbrain:
Plays a crucial role in regulating the basic life-support systems in the body. Blood pressure is controlled in the Medulla, as is the rhythm of breathing heart rate, digestion, and vomiting.——– Death would be just seconds away, was it not for the functioning of the Medulla.
The Pons and the Cerebellum located in the hindbrain are responsible for the system of sleep, arousal, and motor control respectively. The mid-brain has parts responsible for eye movements and reflexive action. In the forebrain, the Thalamus is responsible for being a relay for sensory pathways. The Hypothalamus, which lies below the thalamus is said to be responsible for feeding, drinking, temperature control, and sexual behavior.
The hypothalamus also controls the activation of the sympathetic and parasympathetic systems. “Sympathetic activation causes the anterior pituitary gland to release hormones into the bloodstream; these eventually cause a part of the adrenal glands to release adrenalin, thus energizing the body for dealing with an emergency.”(Levinthal, 1990). Whenever a physical or psychological threat is faced by the human, there is a tendency for the body to respond to the stimulus of perceived or real danger leading to a “fight or flight” response.
This leads to activation of the autonomic nervous system which results in the secretion of various hormones which in turn raises the heartbeat, shortens the breathing rhythm, diverting extra blood to the skeletal muscles to face the challenge and a host of other responses which disturbs the internal balance.
Such responses to a short-term threat are naturally inbuilt in the human being as an evolutionary characteristic. However, should a human face constant stress and trauma, it leads to continuing secretion of hormones and higher than normal stress on the heart and the circulatory system resulting in the long term and irreversible damage. Such cases of prolonged disruption of homeostasis can lead to the death of the human being. The responses, both autonomous and deliberate are processed and generated in the brain and transmitted through the central nervous system to the peripheral nervous system.
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Cognitive Functions of the Brain
The human Brain is unique in the animal world for the level of complexity in cognition. The part of the brain called the cerebrum which is divided into the right hemisphere and the left hemisphere is responsible for problem-solving capability. The left hemisphere looks after communication such as speaking, hand movements while the right hemisphere receives and analyses external information.
Ongoing Scientific Research in the Mechanics of Brain Functions
The explanation of the workings of the human brain and its relation to the other parts of the body is still undergoing further refinements with scientists and researchers grappling with the gaps in understanding of the human brain. Advancement in technology and availability of powerful computers is driving this impetus to enlarge the scope of understanding of the human brain. Computer Axial Tomography (CAT) and Magnetic Resonance Imaging (MRI) now allow a non-invasive structural view of the brain. With Positron Emission Tomography (PET), even the functional status of brain activity is now visible without having to resort to surgical instruments.
According to the Brain research website (2008), brain research is incorporating Cognitive brain research, Molecular Brain Research, and other brain research protocols. Cellular and Molecular Biology of the Nervous System is one area of research in which the genetic bases of structure and function in the nervous system are being examined. The structural organization of the brain is being reexamined through microscopy and non-invasive functional imaging as well as comparative neuro-anatomic studies.
The effect of sleep deprivation on the human body is another area of research that involves detailed research into the functioning of the hypothalamus which is known to control sleep functions. According to Dumer and Dinges(2005) “Although much is known about the neurobiology of hypothalamic mechanisms involving sleep-wake regulation, much less is known about how these systems interact and alter waking neurocognitive functions”. Some offbeat research also looks at the effects of soothing music on the maintenance of Homeostasis. According to Atwater (Jan 2004) of the Monroe Institute, listening to binaural beats, mixed with soft music such as the sound of the surf helps in synchronization of the two hemispheres of the brain leading to altered brain waves which are conducive for relaxation and healing.
The Monroe Institute has backed its research with scientific measurements and documented success stories of their technique which has been patented. The way the brain processes emotions is subject to intense study. According to Rimmele (2003), the amygdala and hormones play a role in influencing memory enhancement for emotionally arousing stimuli. When humans are under stress, the hormone cortisol is released which acts to impair memory.
The effect of good nutrition on the development of the brain is another important area of research that affects the lives of the young. Research is also underway to find ways and means to repair the brain. Alzheimer’s disease afflicts millions of people worldwide and is a particularly debilitating disease of the brain. Stem Cell research and the possibility of injecting stem cells to arrest Alzheimer’s disease is a frontier science that involves the best of neurobiology and technology and has a promising future.
The Mysteries of the Brain
While science has progressed far ahead in increasing the awareness of neurobiological processes of the brain, the field of cognitive brain research is still very much in infancy. The concept of memory, short term, and long term are known. How the memory is actually stored in the brain, is still a mystery. Waking, sleeping, concentrating, attention spans are all known to researchers in bits and pieces.
With the recent non-invasive methods of viewing a functional brain, many of the processes are now visible but a clear definition and the workings of consciousness are yet to be found. Consciousness works at different levels and the altered states of consciousness which the human brain is capable of is observable in neurobiological terms but a satisfactory explanation as to why such states exist is yet to be found. Behavioral studies attempt to explain human behavior in terms of a priori genetically wired instinctive behavior encoded over millions of years of evolution but fail to satisfactorily explain why the neurobiological aspects of behavior are not consistent with all the precepts of behavioral studies.
Intelligent Quotient (IQ) and Emotional Quotient (EQ) are fascinating concepts that have been quantified by some scientifically devised tests but till to date have no real explanation why two brains can be so different in their operation while retaining a marked similarity in their physiological makeup. Mechanics of the sensation of pain is yet another area that has poor understanding. There is no satisfactory explanation as to why different people react differently to pain and why the threshold of pain differs from person to person.
By common sense, if a person is pricked with a pin he should feel pain. However, it has been well documented among oriental races that during certain religious festivals, people pierce themselves with hundreds of needles without any medication, anesthetics and yet feel no pain. The fact that the placebo effect exists is well known. However, the effect of a placebo varies from person to person which has no known physiological or psychological explanation. All that is offered are theories that are correct and incorrect in varying degrees of validity. Brain researchers in the mechanics of sleep are divided in their support over two competing theories – the Recuperative theory and the Circadian Theory.
The recuperative theory states that humans sleep to regain lost energy while the circadian theory states that the human wake-sleep cycle is a natural cycle modified by the day and night cycle of nature. While the former try and explain sleep in behavioral terms, the latter has a more neurobiological explanation for the phenomenon of sleep. Both theories have their pluses and minuses and neither can explain the inconsistencies in the other. The mysteries of the brain as can be seen are innumerable and it will take science a considerable amount of time to finally solve the riddles.
The human brain is truly the last frontier yet to be conquered by science. The reason why it has proven so resistant to decryption lies probably in the millions of years of evolution that have resulted in the brain evolving into a most complex organ. Compared to the rest of the animal kingdom, the human brain stands unique in its ability to perform not only physiological functions but also cognitive functions of an unusually high order.
In the olden days, learning about the brain and its functions involved dissection which gave a fair idea of the physical characteristics of the brain but very little idea about its functioning. The advent of CAT, MRI, and PET made it possible for scientists to observe living functioning brains without having to invade them. Further advancement in technology and neurosciences hold the promise that in a not too distant future, most of the mysteries of the brain would get solved.
Atwater, Holmes, F. (2004). The Hemi-Sync Process. Web.
Brain Research Website. (2008). Brain Research. Web.
Durmer, Jeffrey S & Dinges, David F. (2005). Neurocognitive Consequences Of Sleep Deprivation. Web.
Levinthal, Charles F. (1990). Introduction to Physiological Psychology. New Jersey. Prentice-Hall, Inc. Page 58 and page 60.
Rimmele, Ulrike. (2003). Emotions, Learning and Brain Research. Web.