The Mechanism of Transmission of an Impulse along a Neurone - Essay Example

? NERVE IMPULSE (The Mechanism of Transmission) by: ID Number Presented of the SchoolLocation Estimated Word Count: 1,054 Due on: March 10, 2013 Introduction The human species has evolved over the years into a highly-complex organism, which is why humans are called as the highest-level sentient beings around in this universe. A human body has many biological systems working in tandem and in perfect harmony to synchronize these various body functions. There are ten major systems in humans, which are the following: the circulatory system, the digestive, integumentary, musculo-skeletal, respiratory, reproductive, endocrine, urinary, immune, and finally, the nervous system. The human body is a complex or very complicated organism and one system that is not functioning properly will have adverse consequences, such as the onset of various ailments and chronic diseases. The nervous system can be considered as the most sensitive of these systems because these help humans to survive in a hostile environment, because the nervous system helps in early detection of dangers, through the perception of external and internal stimuli from all the five senses. Essential vitamins, minerals, and vital nutrients are necessary for the nervous system to function properly; additionally, these should ideally be complemented with a good diet, the recommended healthy lifestyle habits, and a regular physical, and also mental, exercise. The nervous system is made up of the brain, the spinal column, and the nerves, which are the highly-specialized cells called neurons, which are the cells responsible for the transmission or receiving of information from signals and stimuli. The nervous system can be grouped into its central system (composed of the brain, the spinal column, and the twelve cranial nerves, in which two pairs emerge directly from the cerebrum while ten pairs of nerves emanate lower from the brain stem), and the peripheral system (that is made up of the spinal nerves). The focus of this paper is how the nerves are able to communicate with each other by examining the manner of transmission; in other words, how signals are sent and received by the cells. A corollary discussion is the role of neurotransmitters which utilize chemicals and electricity. Discussion To better understand how neurons are able to transmit signals and communicate with each other, it is best to learn a few basic things about the structure of a nerve cell, or a neuron. It is composed of a nucleus (the main body of the cell), the axon, and the dendrites. The nucleus is further made up of the basic genetic information (DNA), the organelles (of mitochondria and Golgi bodies), liquid cytoplasm, and the cell membrane. A neuron is unique among body cells because its membrane can communicate with other cells via the transmission and receiving of chemical and electrical signals. The process is in turn facilitated by connections with the gaps between nerve cells known as synapses by an electrical action potential (differences in the electrical charge caused by the level of calcium ions in the neuron cell membrane). The neuron accomplishes this task of communication through its axon and dendrites. An axon is that part of a nerve cell that extends outwards to send a signal; it is the elongated fibre that protrudes from the cell body (called as soma). Its counterpart on a nearby cell is the dendrites, which receives the signal from the axon. As comparison, an axon is thinner and longer when compared to a dendrite, which is shorter but thicker in diameter. In simple terms, an axon is the output zone of the neuron (sender), while the dendrites are the input zones (the receivers). There is a very tiny gap between an axon and a dendrite, and the signal is sent or transmitted by the use of electrical signals, in which the gap (synapse) is bridged by jumping across it. It is just like an ordinary but incomplete electrical circuit, but this time, the neurotransmitter is sent across when an action potential of an electric charge exceeds the threshold limit of a cell. A neurotransmitter is actually a form of a cell message that is composed of certain chemicals, that in turn, are received by the receptor proteins of the receiving nerve cell. This completes the complex and well-coordinated mechanism of the transmission of signals between nerve cells. Any malfunction can cause serious disabilities, as signals are not sent or received well. The whole process or mechanism of transmission of signals between nerve cells can be quite accurately compared to a series of switches, which complete the electrical circuit. A correct level or amount of calcium ions must be present within the plasma membrane for the whole process to take place by triggering the electrical signal (Starr & McMillan, 2008:245). There are an estimated 100 different kinds of neurotransmitters, of which dopamine is the best well known, because it has been linked to Parkinson's and Alzheimer's (if there is a deficit) while too much of dopamine has been suspected to cause dyslexia and schizophrenia, among many other motor-related and psychological ailments of which are only now being researched. The nervous system can be likened to a command centre, which enables an individual to function properly by coordinating all the body systems. An example of how crucial the nervous system is the link between the digestive system and the nervous system. The link is called as enteric nervous system (ENS) consisting of about one hundred million nerve cells, starting from the esophagus (entry point of food) up to the anus (exit point of waste). The ENS neurons are all part of the sensory neurons (in the sense organs); the other two types of neurons are the motor neurons (for movement or locomotion), and the interneurons (for communication of cells). A neuron of the ENS is a part of the autonomic or involuntary nervous system which includes vital functions like heartbeat, urination, breathing and digestion (Tortora & Derrickson, 2012: 925), which in turn forms part of the overall peripheral nervous system in humans. Conclusion Neurotransmitters sent by a pre-synaptic neuron are received by the dendrites of a neuron that is post-synaptic in a self-propagating wave of electrical depolarization (Chiras, 2011:193); its speed of transmission is determined by the presence of myelin (the lining or insulation of the neuron), without myelin, the speed is only 2 feet per second, but with myelin, it increases to about 200 meters per second. It explains why a person can be ataxic if myelin is damaged. References Chiras, D. (2011) Human Biology. MA, USA: Jones & Bartlett Publishers. Starr, C. & McMillan, B. (2008) Human Biology. KY, USA: Cengage Learning. Tortora, G. J. & Derrickson, B. H. (2012) Principles of Anatomy and Physiology. NJ, USA: John Wiley & Sons, Incorporated. Read More