The+Nervous+System

The Nervous System

=Nervous system is one of the most complex systems in our body. It helps all the parts of the body communicate with each other. Besides, the Nervous system also helps the body maintaining __//**homeostasis**//__, which is the internal balancing of making the body‘s state stable, back to normal. And so the Nervous system contributes to maintain it by controlling and regulating ("Body System"). =



__The neuron__

//__Neuron__// is the highly specialized cell in nervous system. It has 3 parts, cell body, //__dendrites__//, and //__axon.__// Schwann cell, //__synapse__//, and __//terminal//__ take job of transmitting signals. On the other hand, dendrites are the one that receive the signals (Nowicki 876).





__//Resting potential//__ means that no signal is transferred. Therefore, there are more of Na+ outside the cell and more of K+ inside the cell (Nowicki 877).

__//Action potential//__ is indicated when an electrical impulse moving down the axon. It’s started by the stimulus, which is the one that meant something that cause a response. Meanwhile, the Na+ enters and the cell becomes positive. K+ leaves and then the area of positive charge moves, which involved __//sodium-potassium pump//__. There are vesicles that contain chemical signals which called __//Neurotransmitters//__. The impulse reaches to terminal, then the force moves the vesicles to contact with terminal’s membrane. The vesicles release Neurotransmitters. And they bind to receptors of adjacent neuron, causes Na+ channel opens and continue the action potential at another neuron (Nowicki 877).

There are 3 kinds of neurons
 * Sensory neurons
 * Interneurons
 * Motor neurons

 Sensory neurons are found in PNS; it detects stimuli and sends signals to CNS.

Interneurons are in CNS. They transmit and interpret signals in brain and spinal cord.

Motor neurons are part of the PNS. Its job is to produce response by bringing the messages from CNS to the muscles target organs (Nowicki 877).

__ The CNS and PNS __

There are two main subsystem divided in nervous system, __//Central Nervous System (CNS//__) and __//Peripheral Nervous System (PNS)//__ (Nowicki 885).

Central Nervous System is made up of the brain and spinal cord.

Brain controls all of the body system and organs, keep they work normally. Brain makes us think, imagine… and behave. Brain contacts with the whole body through spinal cord and nerves ("The Nervous System").

<span style="font-family: Arial,Helvetica,sans-serif; font-size: 140%; line-height: 19px;">__//Cerebrum//__ is part of the part that has job of interpreting signals from the body and form responses. It has left and right halves, or can be called hemispheres (Nowicki 886).

<span style="font-family: Arial,Helvetica,sans-serif; font-size: 140%;">The outer layer of the cerebrum is the __//cerebral cortex//__. It interprets the information of sensory organs and forms responses (Nowicki 887).

<span style="font-family: Arial,Helvetica,sans-serif; font-size: 140%;">The __//cerebellum//__ part of the brain is like a bell, which coordinates your movement and maintains your balance and posture (Nowicki 888).

<span style="font-family: Arial,Helvetica,sans-serif; font-size: 140%;">The __//brain stem//__ is like a main house poll that connects the brain to the spinal cord, which controls basic life activities. There are 3 parts:
 * <span style="font-family: Arial,Helvetica,sans-serif; font-size: 140%;">Midbrain
 * <span style="font-family: Arial,Helvetica,sans-serif; font-size: 140%;">Medulla oblongata
 * <span style="font-family: Arial,Helvetica,sans-serif; font-size: 140%;">Pons (Nowicki 888)



<span style="font-family: Arial,Helvetica,sans-serif; font-size: 140%;">The spinal cord runs down to a tunnel of holes in your back bones or spine. The bones are the protectors. The cord is a thick and dense bundle of nerves, which connects the brain to the whole body ("The Nervous System").

<span style="font-family: Arial,Helvetica,sans-serif; font-size: 140%;">//__Reflex arcs__// are the nerve pathways that just only need to cross 2 synapses. It never has to travel up to brain and spinal cord like others (Nowicki 889).



<span style="font-family: Arial,Helvetica,sans-serif; font-size: 140%; line-height: 115%;">Peripheral Nervous System is also divided into 2 major parts, but 4 systems of nerves. Such like, s__//omatic nervous system (voluntary)//__, __//autonomic nervous system (involuntary)//__, __//sympathetic nervous system (action and stress)//__, and __//parasympathetic nervous system (calm and relaxation)//__ (Nowicki 890).



<span style="font-family: Arial,Helvetica,sans-serif; font-size: 140%; line-height: 115%;">2 parts of PNS are


 * <span style="font-family: Arial,Helvetica,sans-serif; font-size: 140%; line-height: 17px;">Sensory system
 * <span style="font-family: Arial,Helvetica,sans-serif; font-size: 140%; line-height: 17px;">Motor system

<span style="font-family: Arial,Helvetica,sans-serif; font-size: 140%;">The Sensory system detects information of the body and surrounding.

<span style="font-family: Arial,Helvetica,sans-serif; font-size: 140%;">The Motor system starts voluntary and involuntary responses within the body (Nowicki 889).

Thanks to:

<span style="font-family: 'Times New Roman',Times,serif; font-size: 16px; line-height: 32px;">"The Nervous System." // Welcome To The Nervous System //. ORACLE ThinkQuest. Web. 16 May 2011. "Body Systems and Homeostasis." // Mader //. 1997. Web. 14 May 2011. <span style="font-family: 'Times New Roman',Times,serif; font-size: 16px; line-height: 32px;">Nowicki, Stephen. "Human Biology." // McDougal Littell Biology //. Evanston, IL: McDougal Littell, 2008. 874+. Print.



<span style="color: #e368cc; font-family: Arial,Helvetica,sans-serif; font-size: 150%;">Picture citation:

[] <span style="margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px;"><span style="font-family: 'Times New Roman',Times,serif; font-size: 16px; line-height: 32px;">Nowicki, Stephen. "Human Biology." // McDougal Littell Biology //. Evanston, IL: McDougal Littell, 2008. 874+. Print.

<span style="color: #a21010; font-family: Verdana,Geneva,sans-serif; font-size: 140%;">For some more references:

<span style="font-family: Arial,Helvetica,sans-serif; line-height: 27px;"> Wikipedia : []

ThinkQuest: []

Children's Hospital Boston: []

Dummies: []

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