Nervous System

Hugo Yu

What is the Nervous System?

The nervous system is a body-wide system that, basically, tell everything what to do. The nervous system consists of the Brain (which has smaller counterparts) and Spinal cord, creating the central nervous system, The peripheral nervous system, the sympathetic nervous system, and the parasympathetic nervous system.

What does the Nervous System Do and How Does It Work?

The Nervous System is the control center for your body. It sends signals from the brain to your other body systems and tells them what to do. Your sensory body systems, such as your eyes and sense of touch, will send signals to the brain to receive commands back.


Reflexes are involuntary actions. Most simple reflexes, such as taking your hand away from the burning stove (but why would you do that in the first place?) when you sense the pain and heat. This action doesn't involve the brain, but does require the spinal cord. The sense (pain) is transmitted along neurons to the spinal cord, part of the central nervous system, and immediately sends back a "move your hand away" response. When you actually feel the pain, your hand has already begun to move away, because the brain is unaware of anything until it receives the signal that says, "Ouch!"

Sometimes, the reflex is more complicated, like stepping on a sharp object, because sure, you moved your foot away, but you still have to balance yourself, right? More complicated reflexes do require the brain.


So, the reflex "signal" goes to the spinal cord or brain, then back, but how does it travel? You probably have heard of nerves, which are actually a cluster of neurons, individual nerve cells. Each neuron consists of a cell body (with all the organelles), an axon (a "long", tubelike extension) and dendrites, the much shorter extensions. The cell body, is where the nucleus and all that stuff is. The axon, is where the length of a neuron is important. The longer the axon, the less neurons, but also the slower the transmission. The dendrites, which lock in (but don't touch) with the axon of the next neuron. The dendrites are the receiving end of the neuron, and the axon moves it on to the next neuron. The neurons don't touch though, there is a small gap called a synapse between the two, where neurotransmitters bridge the gap.

How are the nerve signals created?

The signals, or impulses, are created by neurons and electricity. The neurons normally in an undisturbed state are more negative than their surroundings. When the impulse is created, the neuron becomes more positively charged. When it returns to its normal state (this is an extremely quick process), it has sent an impulse

The Cerebellum

Basically, the cerebellum is a mini brain that controls your balance. It is below the cerebrum.

Disorders and Diseases

There are several disorders including Stroke, Alzheimer's, Bipolar, and Epilepsy. Alzheimer's is a commonly known disease that is typical in people over the age of 65. There is no known cause, and symptoms include memory loss, confusion, and deterioration of certain mental functions. There are some "cures", such as Donepezil, Galantamine, Memantine Rivastigmine, although exercise and vitamin E will help as well.