Sistema Nervioso (Ingles)

2011
Nervous System…

|



Your nervous system is the control and communication system of the body. Its job is to send and receive messages. Your nervous system controls all your thoughts and movements.

PARTS OF THE NERVOUS SYSTEM

   The cells that make up the nervous system are called neurons. Long, stringy neurons areperfect for carrying the electrical messages that are the "language" of the nervous system.
Content

Parts of Neuron
Each neuron consists of three parts –
Cyton – It is a part of neuron which has large nucleus. Many granules and fibres are found in the cytoplasm. These granules are known as Nissl’sgranules and fibres are called neurofibrils. Mitochondria and Golgi complex are also found in cytoplasm.
Dendrons – Many short processes that come out of the cyton are known as dendrons. Each dendron gives off fine branches which are called dendrites. These processes connect nerve cell with the other.
Axon - Axon is the longest process gives off from the cyton. It is thicker than the other processand its other end is divided into many branches. These branches are known as collateral fibres. Neurofibrils are found in dendrons and axons both but Nissl’s granules are not present in axons. Impulses are first received by dendrons, from where they go to cyton and passed onward through axon. The end fibres of one axon are placed very near to the dendrites of other cyton. This place of contactbetween the two nerve cells is known as synapse. Each axon is surrounded by several membranes. These membranes and axon together constitute the nerve fibre. Each axon fibre is covered by a thin membrane called neurilemma, below which flat Schwann cells are found. A thin layer of fat, called myelin sheath or medullary sheath is present between the axon and neurilemma. This sheath is broken at placeswhich are called nodes of Ranvier. The part intervening between two nodes are called internodes.

The Hindbrain
Having evolved hundreds of millions of years ago, the Hindbrain or the Reptillian Brain is the oldest part of the human brain. As you might guess from it's name, it's a piece of brain anatomy that we share with reptiles and is the most primitive. Likewise it's in charge of our primalinstincts and most basic functions. Things like the instincts of survival, dominance, mating and the basic functions of respiration, heartbeat all come from this area of the brain. Located in the Hindbrain are:
* The Spinal Cord
This is the infomation superhighway of the body. It carries information up to the brain and instructions back down.
* The Medulla Oblongata
Helps control thebody's autonomic functions (things you don't need to think about to perform) like respiration, digestion and heart rate. Also acts as a relay station for nerve signals going to/from the brain
* The Pons
Has a role in your level of arousal or conciousness and sleep. Relays sensory information to/from the brain. Also involved in controlling autonomic body functions.
* The Cerebellum
Mostlydeals with movement. It regulates and coordinates movement, posture and balance. Also involved in learning movement.
The Limbic System
The Limbic System sometimes called the "emotional brain" or "Old Mammalian Brain" is the next brain to have evolved in the more primitive mammals about 150 million years ago. This is where our emotions reside, where memory begins and where these two functions combinetogether to mark behaviours with positive or negative feelings. It's where mostly unconcious value judgements are made. Information going through the Limbic System are filed under "agreeable or disagreeable". It also plays a role in salience (what grabs your attention), spontaneity and creativity. Located in the Limbic System are:
* The Amygdala
It's name is latin for almond which relates...