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<h1>The great control center.</h1>
<p>The nervous system ensures the internal communication of the human body while it relates to the external environment through the organs of the senses. All the physiological functions are interrelated through the internal senses, which are in charge of informing at all times the nervous centers of the general state of the body. When studying the nervous system, it is divided into two sectors: the central and the peripheral. The central nervous system is the nucleus that controls everything that happens in the organism and, like in the rest of the vertebrate animals, it is constituted by two centers: the encephalon and the spinal cord. The peripheral nervous system is constituted by the set of nerves that, starting from the encephalon and the medulla, extends towards all the parts of the human body.</p>
<p><img src="https://steemitimages.com/0x0/https://upload.wikimedia.org/wikipedia/commons/thumb/b/b2/TE-Nervous_system_diagram.svg/1200px-TE-Nervous_system_diagram.svg.png" width="1200" height="1410"/></p>
<p><a href="https://en.wikipedia.org/wiki/Nervous_system">Source.</a></p>
<h1>The neuron.</h1>
<p>Neurons or nerve cells are basic units of the functioning of the nervous system. They are formed by three parts: The neuronal body, which houses a large, spherical nucleus; the dendrites, which are branches whose basic function is to capture stimuli and transmit it to the neuronal body; and the axon, an elongated part whose basic function is to send nervous stimuli to the dendrites of nearby neurons. Neurons communicate with each other thanks to the connection between the axons of some neurons with the dendrites of others, so that each neuron can be stimulated by thousands of neurons and stimulate others at the same time.</p>
<p><img src="https://steemitimages.com/0x0/https://upload.wikimedia.org/wikipedia/commons/thumb/b/b5/Neuron.svg/1200px-Neuron.svg.png" width="1200" height="645"/></p>
<p><a href="https://simple.wikipedia.org/wiki/Neuron">Source.</a></p>
<h1>The nerves.</h1>
<p>The nerves are formed by groups of axons, with the blood vessels that accompany them and by the connective tissue that surrounds them with fibrous tissue that form a nerve. Depending on the physiological function of a nerve in the organism, its neurons are classified as sensory or motor. Most nerves contain as many sensory and motor neurons. The sensitive ones transport nerve impulses from the sensors of the body to the central nervous system; the motors transport, from the central nervous system, the orders to contract the muscles.</p>
<p><img src="https://steemitimages.com/0x0/http://tozapping.com/wp-content/uploads/2018/03/Tozapping-remedios-caseros-para-los-nervios-736x685.jpg" width="736" height="685"/></p>
<p><a href="http://tozapping.com/remedios-caseros-para-los-nervios/">Source.</a></p>
<h1>The central nervous system.</h1>
<p>It is formed by the brain and spinal cord as well as by millions of neurons and glial cells, among other components. The encephalon and the spinal cord, given their importance, are strongly protected from trauma. Its first protection is a bone covering, which in the brain is the skull and in the spinal cord is the spine. Second, they are protected by three membranes called meninges. The outermost is called arachnoid, and the innermost is the pia mater and contacts the nervous system. Finally, it is also covered by the cerebrospinal fluid, which fills the space between the membranes of the meninges and between the cephalic cavities.</p>
<p><img src="https://steemitimages.com/0x0/http://d1aueex22ha5si.cloudfront.net/TEMP/DQmPA6vtBwUHETzzMxM3Usb32dbCo8xEUKaytLPxmuvcn5n_1680x8400-1514383814807.jpg" width="640" height="480"/></p>
<p><a href="http://infectiousdiseasescongress.alliedacademies.com/events-list/central-nervous-system-infections">Source.</a></p>
<h1>In encephalon.</h1>
<p>The encephalon is the center that coordinates all the functions of the organism. It is, therefore, where the stimuli coming from the organs of the senses and the motor areas are collected and made conscious. It is divided into three regions: cerebral, cerebellum and brainstem. The outer part of the brain, or cerebral cortex, is formed by gray matter, while the inner part is formed by white matter. The gray matter of the cerebral cortex is responsible for coordinating all the functions of the organism and is the center of intelligence, will and memory. The cerebellum is responsible for regulating muscle movements and controls the balance of the body. The brainstem gathers all the structures that exist between the brain and the spinal cord and regulates the vital activities of reflex type, such as respiratory, circulatory or cardiac.</p>
<p><img src="https://steemitimages.com/0x0/https://i.pinimg.com/originals/12/95/9d/12959dbafea9d4c4fbb229c2c140ceae.jpg" width="800" height="600"/></p>
<p><a href="https://www.pinterest.es/pin/576320083543390761/">Source.</a></p>
<h1>Spinal cord.</h1>
<p>The spinal cord is the nerve cord that goes down from the brain through the inside of the spine and reaches the height of the second lumbar vertebra. There follows a filament and fibrous that receives the name of filum terminale. The nervous impulses of the body go up to the body through the spinal cord and the orders that the brain directs to any part of the body go down. Contrary to what happens in the brain, here the gray substance is found in the inner part of the marrow and the white substance in the outer part. Modular nerves emerge from the sides of the spine. In total there are 31 pairs that connect the different regions of the organism with the marrow, and therefore with the central nervous system. Each medullary nerve is divided into two roots, just before joining the cord.</p>
<p><img src="https://steemitimages.com/0x0/https://s3.amazonaws.com/reeve-assets-production/BrainSpinalCordlabld.jpg" width="752" height="1024"/></p>
<p><a href="https://www.christopherreeve.org/living-with-paralysis/health/how-the-spinal-cord-works">Source.</a></p>
<h1>The peripheral nervous system.</h1>
<p>The peripheral nervous system is constituted by the set of sensory nerves that carry information to the central nervous system, either relative to the interior or exterior of the body, and also by the motor nerves that start from the central nervous system and go to the different organs of the nervous system. body to give timely responses to the stimuli received. In the peripheral nervous system, the 12 pairs of cranial nerves and 31 pairs of medullary nerves are differentiated. This wide network of nerve cords branches off every corner of the body.</p>
<p><img src="https://steemitimages.com/0x0/https://upload.wikimedia.org/wikipedia/commons/thumb/5/5b/Nervous_system_diagram-en.svg/1200px-Nervous_system_diagram-en.svg.png" width="1200" height="1333"/></p>
<p><a href="https://en.wikipedia.org/wiki/Peripheral_nervous_system">Source.</a></p>
<h1>The autonomic nervous system.</h1>
<p>The function of the autonomic nervous system is to control the activities of the different apparatuses of the body, such as the digestive, the urinary and the circulatory. To achieve this, it transmits nervous impulses to the organs of the body. This system is characterized by being involuntary (autonomous) and usually does not originate sensations. The autonomic nervous system is formed by nerve fibers and has different points of origin in the central nervous system. It is divided into the sympathetic and parasympathetic systems, which work in an antagonistic way: the first stimulates the organs and the second inhibits them. This opposite work ensures balance in the organism.</p>
<p><img src="https://steemitimages.com/0x0/https://psychlopedia.wikispaces.com/file/view/autonomic.gif/324424436/480x367/autonomic.gif" width="480" height="367"/></p>
<p><a href="https://psychlopedia.wikispaces.com/Autonomic+Nervous+System">Source.</a></p>
<h1>The alarm and the calm.</h1>
<p>The sympathetic nervous system is formed by nerve fibers that start from the spinal cord. It acts against alarm states, such as fear or fatigue, so it prepares the body for the expenditure of energy. On the contrary, the parasympathetic nervous system, which is formed by some pairs of cranial nerves and also by nerves that are born in the sacral region of the medulla, acts to calm situations and prepares the body for rest. It decreases the heart rate and lowers blood pressure. Stimulating the digestive system for the elimination of food waste. In most cases, impulses from the sympathetic actively stimulate the organs, while parasympathetic impulses depress or inhibit this activity.</p>
<p><img src="https://steemitimages.com/0x0/http://tendenzias.com/wp-content/uploads/2013/05/image_thumb5.png" width="490" height="307"/></p>
<p><a href="https://tendenzias.com/life/por-qu-cuando-tenemos-miedo-abrimos-tanto-los-ojos/">Source.</a></p>
<p><img src="https://steemitimages.com/0x0/https://gcdn.emol.cl/espiritualidad/files/2011/12/meditar.jpg" width="614" height="301"/></p>
<p><a href="https://www.guioteca.com/espiritualidad/tres-pasos-para-encontrar-la-calma/">Source.</a><br>
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<h1><strong>Nervous diseases.</strong></h1>
<p>Most diseases of the nervous system have no definite cure, and can only be placated and controlled. One of the most important is multiple sclerosis. Today, this disease is incurable, is degenerative and impairs the transmission of the nerve impulse, so its effects are sensitive and motor. Epilepsy is one of the most frequent neurological diseases and its crises are caused by an exaggerated nervous impulse of a group of brain neurons. Chronic headaches, or headaches, neuralgias and depressions are classified as nervous diseases and currently affect a significant amount in society.</p>
<p><img src="https://steemitimages.com/0x0/https://cdn.hispantv.com/hispanmedia/files/images/thumbnail/20121103/19183119_xl.jpg" width="450" height="299"/></p>
<p><a href="https://www.hispantv.com/noticias/salud/150682/fibras-nerviosas,-nuevo-metodo-para-curar-la-em">Source.</a><br>
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