The nervous system is one of the first systems to start developing in the body and is one of the last systems to finish developing. Perhaps, it is this system that coordinates the activities of human biological organs in response to signals taken from the external and internal environment (Rhoades & Bell, 2012). Even in a single touch on the human skin, it is the nervous system that operates in order to let the skin identify that touch. But within the nervous system, there are certain components that actually work in this. In fact, the nervous system is divided into two major components: CNS and PNS. These can be further divided into the different organs that regulate them. The core component of the nervous system is the neuron and it is a highly specialized cell.
The neuron is the fundamental cell of the nervous system. It consists of a few basic components. The cell nucleus contains the DNA, which is the genetic programming for the neuron. Dendrites extend off the cell body in order to receive incoming messages into the cell. The axon moves away from the cell body and is covered in a fatty lipid sheet of cells called the myelin sheath. The end of the axon forms a space between the next dendrite called the synapse. This is where neurotransmitters are secreted from the synaptic vesicles to interact in the synapse.
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The neurons in the nervous system communicate via action potentials. This is dependent on a sodium/potassium pump that regulates ion flow in and out of the synapse. At resting potential, the nerve has an approximate charge of -70 mV. During depolarization, sodium ions move into the cell causing the potential of the neuron to rise. Once the action potential is at 30 mV, the action potential fires down the neuron, hopping down the nodes of Ranvier until it reaches the synaptic vesicles that are stimulated by the electrical charge. These synaptic vesicles then release neurotransmitters into the synapse to communicate with the receptors on the other side. At the end of the action potential, repolarization of the membrane occurs as ions move back to their equilibrium concentrations to reach the base -70 mV until another action potential needs to be produced. The action potential is an all-or-nothing event in that either the action potential is going to occur or it will not. Some neurons of the body have to produce action potentials very rapidly, whereas others are barely used. Additionally, regarding receptors, study shows that a larger receptor cannot produce larger action potential but it can “induce more rapid firing of action potentials” (Sherwood, 2012). That means, more neurotransmitter will be released as an afferent fiber fires more rapidly.
Another thing in the nervous system is the reception and transmission of electrochemical signals. Nervous tissues consist of neurons, which are known as “specialized signaling cells”, and the cells that act as supports for them. The cell body is protected by long cytoplasmic extensions which allow the cell to receive and transmit electrochemical signals (Starr, Evers, & Starr). When a neuron receives enough stimulation, an electrical signal will be transmitted into the cytoplasmic extensions, then to other neurons, changing the behavior of a particular cell. The principles of the electrochemical signal can be applied to all neurons in the nervous system. The chemistry of the body is translated into electric signals, which actually causes humans to emit a slight electromagnetic field that is detectable. This is how predators, such as sharks, are able to detect their prey. It is also because our bodies are in essence an ionic solution that allows these ions to exist and for these electrochemical changes to occur. Without this, signal transduction and action potential events could not occur.