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Central And Peripheral Nervous System For Fast Functioning

Posted by rafael on June 1, 2012 in News

The human body is composed by several system. They are the respiratory system, circulatory system, excretory system, nervous system, digestive system, reproductive system, endocrine system and osseo-muscular system. As several specialized sources report, the nervous system is the most complex and unknown of all them.

It ensures the function of the human body, working closely with the endocrine system. Particularly, the nervous system receives and integrates data from different human sensory organs, and accordingly elaborates and transmits responses. This system usually handles fast functioning activities, but at the same time is responsible for such intellective functions as emotions, memory, or reasoning.

The anatomical constitution of the nervous system is quite complex. Furthermore, alike others cells composing the human body, nervous system’s cells do not regenerate. It is divided into central nervous system and peripheral nervous system.

Central Nervous System

The central nervous system (CNS) consists of the spinal cord and the brain. They are protected by three layers, an inner membrane called Pia mater, a middle membrane known as arachnoid, and an outer membrane, called Dura mater (or just Dura), the three of them generically known as meninges. Moreover, bone casings (skull and spine) protect the brain and spinal cord respectively.

Cavities of these bodies (ependymal canal in the case of the spinal cord and ventricles in the case of the brain) are filled with a colorless clear liquid known as cerebrospinal fluid. This liquid serves to maintain a proper ion balance within the human body, as a waste products’ elimination system, as an exchange mean of some specific substances, and as a shock absorber system.

The central nervous system performs several essential functions for the human body.  First, it perceives stimuli from the outside world. Second, the central nervous system transmits nervous impulses to the specific processing centers, depending on the specific stimuli it received. Third, it produces response impulses to these stimuli. Fourth, CNS transmits these impulses to skeletal muscles.

These functions are possible due to the existence of neurons. They are considered as the nervous system’s functional unit. Neurons are nerve cells serving as communicating link between receptors and effector organs in the human body, which perform this task through system nerve fibers. The human CNS has about 10 billion neurons. They consist of three parts:

  • Axon: long ending (can reach 1 m length);
  • Dendrites: nerve endings;
  • Body or soma: mainly composed cytoplasm, nucleus, and nucleolus.

The axon has multiple endings that are in proximity to dendrites or body of another neuron. The separation between the axon of one neuron and dendrites or body of another is just about 0.02 microns. The relationship between the axon of one neuron and the dendrites of another is called synapses. Precisely, thorough synapses takes place the process of communication or transmission of nervous impulses, i.e., through synapse a neuron sends message impulses from the axon of one neuron to the dendrites or the body of another.

Synapses has several characteristics. First, the conduction of nerve impulses is performed just in one direction, i.e., from the axon of one neuron to the body or dendrites of another neuron. Second, the nerve impulses spread through chemical intermediates (for example, norepinephrine, acetylcholine), released by the axon terminals of the first neuron. When these chemical intermediates are received by the second neuron, they incite the production of a new impulse; and so on, the process is repeated. Third, there are excitatory and inhibitory neurons in the central nervous system, and every one releases its own mediator substance. Fourth, the speed of conduction of an impulse along nerve fibers ranges from one to 100 meters per second, being higher while the distance is longest. Fifth, a synaptic fatigue can occur if the synaptic terminals are stimulated continuously; as a result, the amount of transmitted impulses diminish. Finally, there is a delay of just five milliseconds from in the transmission from one neuron to another.

Peripheral Nervous System

The peripheral nervous system (PNS) is made up of nerves and neurons that are located outside the CNS and extent to the limbs and organs of the human body. Alike the CNS the peripheral nervous system is not protected by bones or brain barriers, allowing its exposure to mechanical damage and toxins. The PNS is in charge of coordinating, integrating and regulating the function of internal organs, mainly through unconscious responses. It is further divided into:

  • Autonomic or vegetative nervous system: It is responsible for regulating body functions, controlling heart, smooth muscles, glands, and guts according to CNS instructions. It carries out this regulation under three branches: sympathetic, involved in activities requiring energy expenditure; parasympathetic, in charge of gastric motility, as well as storing and conserving energy and; enteric, coordinating the peristaltic reflex and regulating the gastrointestinal activity. This system is composed of plexus (lumbosacral, brachial and cervical), roots (sacred, cervical, lumbar and thoracic dorsal) and nerves (lower limbs nerves, upper limbs nerves and cranial nerves)

  • Somatic nervous system: This system is associated with the control of body movements. It is composed of spinal nerves and cranial nerves. Spinal nerves are responsible for sending sensory information (pain, touch, etc.) from the limbs or trunk to the CNS via the spinal cord. Furthermore, they also transmit information linked to the conditions and position of joints and muscles of the trunk and limbs. Moreover, these nerves receive motor commands from the spinal cord in order to control the skeletal muscles. There are 31 pairs of such nerves, each one having two roots, one motor and other sensorial. Particularly, the motor root carries impulses from the spinal cord to efferent nerves (effectors), while the sensory root carries impulses from the afferent nerves (receptors) to the spinal cord. On the other hand, cranial nerves send sensory information from the neck and head to the central nervous system. There are 12 of these nervous, such as optic nerve, trigeminal nerve, facial nerve, oculomotor nerves, among others.

If you are looking for more information on the central and peripheral nervous systems, check the links below:

Brain is the main organ of the body that controls everything in a human body. All the organs are in control of the brain and functions only when the brain commands. The organisms are under the control of brain too since they can not even associate with their corresponding organs until unless commanded by the brain. That’s not the end brain controls all the six senses present in a human. It is the brain that allows you to see the upside image captured by your eye into a straight and normal, it is none other the brain that let you smell the curry as sour, it is again the brain that help your hear with the waves of air, it is the brain also that alert you even when the wind touches you, the brain makes you know the taste of anything and last, but certainly not the least it is the brain only that makes you vision the future.

Central And Peripheral Nervous System For Fast Functioning

Central And Peripheral Nervous System For Fast Functioning

What Helps Brain Do Such Extra Ordinary Things

Brain is connected to the central and peripheral nervous system that helps it to spread its messages in a fast way. The central and peripheral nervous system does not only spreads and delivers the messages fast but also to the right place at the right time. It is said that central and peripheral nervous systems of the brain is responsible for sending / analyzing the messages and working as a substitute organ for the messaging process respectively. It is advocated that brain that becomes incapable of linking itself with the central and peripheral system can no more remain able to control the whole or partial parts of the body. Any disease that causes such a disconnection between the brain and the central and peripheral nervous system should be eliminated soon to save the patient from getting expire.

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