Published on Nervous system.

The nerves represent communication and are part of the nervous system

Nervous system

Published on Nervous system, Useful concepts.

The nervous system is basically divided in two systems:

The Central Nervous System (CNS) and the Autonomic Nervous System (ANS), also called vegetative nervous system.

Nerves are like pieces of string connecting nervous centres to organs. Some nerves are connected to the central nervous system. They are called spinal nerves, and include the rachidian nerves (linked to the spinal cord). There are also the cranial nerves.

There are nerves that are linked to the autonomic system, vegetative parasympathetic nerves and sympathetic nerves.

The peripheral nervous system is formed by all the nerves that do not belong to the central nervous system. The nerves that form the peripheral nervous system are the cranial nerves, which connect the head and face directly to the brain, the nerves that connect the eyes and the nose to the brain, and all the nerves that connect the spinal marrow to the rest of the body.

The brain communicates with most of the body through the 31 pairs of spinal nerves that come out of the spinal marrow. Each pair of spinal nerves includes a nerve in the anterior side of the spinal marrow, which allows the transmission of information from the brain to the muscles, and a nerve in the posterior side of the marrow, which transmits sensitive information to the brain. The spinal nerves join together through plexuses on the neck, the shoulder and the pelvis and, subsequently, they divide again to innervate the most remote parts of the body.

The central nervous system is formed by the encephalon (brain) and the spinal marrow. It rules the voluntary movements of the body.

Conditions affecting this part of the nervous system will be dealt with separately in this book.

The autonomic nervous system controls the vegetative system, which is autonomous: circulatory system, digestive system, respiratory system, reproductive and urinary systems and endocrine system.

It rules the autonomous movements of the body.

It includes the parasympathetic system, which regulates, and the sympathetic system, which stimulates.

The sympathetic system prepares one for fighting or fleeing. It reacts to sudden situations, and is activated by adrenalin. When this happens, the heart beats faster or the blood pressure increases, the trachea expands, breathing becomes heavier, the pupil dilates, there is perspiration, the blood flows to the voluntary muscles of the skeleton (connected to the central nervous system) and the sexual and digestive systems become inactive.

The so-called sympathetic trunk, next to the spine, is formed by a group of nervous cells that do not form part of the CNS and which are called ganglia.

There are muscles that are linked to the central nervous system, which are the voluntary control muscles. They are linked to the skeleton. Their role is to produce movement in the bones of the body, in the skeleton. They are striated muscles. There are equally muscles that are connected to the autonomic nervous system and that are involuntary control muscles and line the walls of both blood vessels and internal organs. Their role is to produce automatic movement in the internal organs. They are smooth muscles.

There appears to be just two exceptions: Muscles in the bladder are smooth, although they are voluntary movement muscles. And the muscles in the heart are striated, although they are involuntary control muscles.

Of all the systems in the body, the nervous system is the slowest to react, because it is the deepest. It is the most yang of the systems. And since cure occurs from the outside inwards, it takes longer to come up. Nervous system.

© Copyright by Luís Martins Simões, developed by RUPEAL