3.	Neurons 
    The cells that make up the nervous system are called neurons  As we see in the picture, the most long and thin extension is the 
axon  and the remaining branches that are more numerous and shorter are called
dendrites .
	
		
		
 
		
    4.	Parts of the nervous system  
   In this system we can distinguish: 
   - The encephalon  that is in the head, it allows us to understand and reason. It has three parts: cerebrum, cerebellum and
medulla oblongata . 
   - The brain  is the most voluminous organ. It is about 1200 to 1600 grams. It is formed of two hemispheres (right and left) joined by nerve fibers. The outside part is the cerebral cortex and is crossed by a wrinkle or gyrus. 
   - The cerebellum  is a nerve center which is located beneath the brain and regulates the movement of the heart and breathing. 
   - The medulla oblongata  is a thick nerve cord placed at the bottom of the brain. it connects the brain and the spinal cord. 
   - The spinal cord  is in the vertebral column.  The nerves come from it. They go to the body to drive the impressions to the brain and return the response to the corresponding organ. 
   - Nerves  are little cords that link the nervous centers and the various organs of the body. 
		
		 
	 
   5.	Select one of these parts of the nervous system : the encephalon , brain, cerebellum, medulla oblongata, spinal cord or nerves 
    
 6.	Autonomic nervous system 
    It consists of two cords (sympathetic and parasympathetic), they are placed on both sides of the vertebral column, it has the mission to direct the movement of various organs: heart, stomach, lungs, etc. 
    
 7.	Hygiene of nervous system 
     We must take into account: 
   - Do not force the nervous system to work in excess because it can cause failures in the function. 
   - Live with good habitudes with fixed working hours and rest. 
   - Do not consume alcoholic beverages or non-medically prescribed drugs. 
   - Do not use drugs because they are highly harmful because they spoil the nervous system and the personality. 
   - Do not abuse of tobacco and coffee. 
   8.	Indicate if these advices are correct or incorrect:  
 
	®Arturo Ramo García.-Record of intellectual property of Teruel (Spain) 
No 141, of 29-IX-1999