Central Nervous System.

The central nervous system (CNS) includes the brain (Latin: 'ensephalon') and spinal cord (Latin: 'spinal cord'). Both are very soft organ, with a very important function it needs protection. In addition to the skull and spine segments, the brain is also protected three layers of the meninges membrane. When the membrane is exposed to infection, inflammation will occur is called meningitis.

The third layer of the meninges membrane from the outside in are as follows :

- Durameter.

Composed of two layers, the outer one with the skull as endostium, and other layers as dura mater easily removed from the skull. Among the bones of the head with the dura mater contained epidural cavity.

- Arachnoidea mater.

So called because it looks like a cobweb. In it there is a liquid called liquor cerebrospinalis, a kind of lymph fluid that fills the gap between the arachnoid membrane. Arachnoidea membrane function is as a cushion to protect the brain from the danger of mechanical damage.

Pia mater.

The innermost layer which has a form adapted to the folds of the brain surface.

Brain and spinal cord has three essential materials, namely :

- The cell bodies.

Which forms part of the gray matter (substance grissea)

- Nerve fibers.

Which forms part of the white matter (substance alba)

- Neuroglia cells.

That is the connective tissue that lies between the nerve cells in the central nervous system
Although the brain and spinal cord have the same material but different composition. In the brain, the gray matter located in the outer or skin (cortex) and the white section in the middle. At the center of the spinal cord gray matter in the form of a butterfly-shaped, while the cortex in the form of white matter.

Brain.

The brain has five main parts, namely: a large brain (cerebrum), midbrain (mesensefalon), small brain (cerebellum), marrow grafting (medulla oblongata), and the bridge Varol.

Large brain (cerebrum).

Large brain has a function in the regulation of all mental activity, which is associated with intelligence (intelligence), memory (memory), awareness and consideration.
Big brain is the source of all activities / voluntary movement or in accordance with the will, although there are also some reflex movements of the brain. In the cerebral cortex of gray are excitatory receiver section (area sensor) located in the rear area of ​​the motor which controls voluntary movement or to respond to stimuli. In addition there is an association area that connects the motor and sensory areas. This area plays a role in learning, memory store, make conclusions, and learn various languages. In the vicinity of the area is the part that regulates the activities of higher psychology. For example, the front is the center of the process of thinking (ie remembering, analysis, speech, creativity) and emotions. Vision center located on the back.

Midbrain (mesensefalon).

The midbrain is located in front of the cerebellum and the bridge Varol. In front of the thalamus and midbrain are the pituitary gland which regulates the endocrine glands work. The upper (dorsal) midbrain is the optic lobe that regulates such eye reflex constriction of pupils, and also a center of hearing.

Small brain (cerebellum).

The cerebellum has a major function in coordination of muscle movements that occur consciously, balance, and body position. When there are adverse or harmful stimuli then normal voluntary movement impossible.

Marrow grafting (medulla oblongata).

Continued marrow function deliver impulses coming from the spinal cord to the brain. Marrow grafting also affect bridge, reflex physiology such as heart rate, blood pressure, volume and respiratory rate, movement of the digestive tract, and secretion of digestive glands.
In addition, marrow grafting also regulate other reflexes such as sneezing, coughing and blinking.

Varol bridge (pons Varoli).

Varol bridge contains nerve fibers that connect the cerebellum to the left and right, also connects the large brain and spinal cord.

Spinal cord (spinal cord).

In the cross section of the spinal cord looks white exterior, while the inside of a butterfly-shaped and gray. In the cross section of the spinal cord there are parts such as wings, consisting of the upper wing is called the dorsal horn and lower wing is called the ventral horn. Sensory impulses from the receptors were ushered into the spinal cord through the dorsal horn and exit the motor impulses from the spinal cord through the ventral horn to the effector. In the dorsal horn neuronal cell bodies contained a link (association connector) which will receive impulses from sensory nerve cells and will deliver them to the motor nerve.

Nerve cells

Nerve cells or neurons is the main working unit of the nervous system that functions to deliver electrical impulses formed by the existence of a stimulus (stimuli). Millions of nerve cells forming a nerve system.

Structure.

Each neuron consists of a cell body in which there are cytoplasm and the cell nucleus. From the cell body out two types of nerve fibers, the dendrites and axons.
Dendrites function sends impulses to the nerve cell body, whereas the function of axons transmit impulses from the cell body to another nerve cell or to another network. Axons are usually very long. Conversely, short dendrites. At the end of the end of the axon synapses that there is a gap between the nerve endings where neurotransmitter is released to deliver impulses to the next nerve or organ in question.
Each neuron has only one axon and at least one dendrite. Both of these nerve fibers containing plasma cells. On the outside of the axon there is a layer of fat called myelin formed by Schwann cells attached to the axon. Schwann cells are the primary glial cells in the peripheral nervous system that serves to form the myelin sheath. Myelin function is to protect and nourish the axon. Part of that is not wrapped myelinated axons are called nodes of Ranvier, which can accelerate the delivery of impulses.

Grouping.

Based on its function, nerve cells can be divided into three groups, namely sensory nerve cells, motor nerve cells, and nerve cells intermediates (association).

Sensory nerve cells.

Sensory nerve cell function is deliver impulses from receptors to the central nervous system, the brain (ensefalon) and spinal cord (spinal cord). Tip of the axon of nerve sensory nerves associated with associations (intermediates).

Motor nerve cells.

The motor nerve cell function is to send impulses from the central nervous system to muscles or glands which results in the body's response to stimuli. The motor nerve cell bodies located in the central nervous system. His very short dendrites associated with nerve axons association, whereas its axon can be very long.

Intermediates nerve cell / nerve cell connectors.

Intermediates nerve cells called neurons association. These cells can be found in the central nervous system and serves to connect the motor nerve cells to sensory nerve cells or in connection with other nerve cells in the central nervous system. Intermediates nerve cells receive impulses from sensory receptors or nerve cells other associations. Groups of nerve fibers, axons and dendrites join in the sheath and form a fibril. While the neuronal cell bodies come together to form a ganglion or ganglion. Thank you for reading this article.
Written and posted by Bambang Sunarno. sunarnobambang86@gmail.com
author:
https://plus.google.com/105319704331231770941.
name: Bambang Sunarno.
http://primadonablog.blogspot.com/2015/09/central-nervous-system.html
DatePublished: September 9, 2015 at 10:37

Tag : Central Nervous System.

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