CENTRAL NERVOUS SYSTEMBRAINBRAINSPINAL CORDSPINAL CORDIt receives and sorts out information coming from the environment and from inside the body and determines the appropriate actionPERIPHERALNERVOUS SYSTEMNerves that extends throughout the bodyThere are 12 pairs of cranial nerves arising from the brains and 31 pairs of spinal nerves arising from the spinal cordIt is where the communication of body cell and tissue occursSOMATIC NERVOUS SYSTEMCommunicates with the skeletal muscleAUTONOMIC NERVOUS SYSTEMCommunicates with smooth muscles heart muscles and glands!hich speeds up or slows down some body processes!hich have opposite effect on thesame body processesFUNCTIONSIt receives information from the environment and inside the bodyIt interprets the information it receivesIt makes the body respond to the informationNEURONThe nervous system carries signal throughout the body in the form of nerve impulses." nerve impulse is a small electrical charge#!hat system also have an small electrical charge$DENDRITESCELL BODYNUCLEUSAXONNODE OF RANVIERMYELIN SHEATHAXON KNOBDENDRITE OF A NEURONSIGNAL OR MESSAGESIGNAL OR MESSAGETRAVELS ALONG THE NEURONREACHES THE END OF THE AXONTRIGGERS THE KNOBNEUROTRANSMITTERNEUROTRANSMITTERCHEMICAL PASSES THROUGH SYNAPSEREACHES ANOTHER DENDRITESDENDRITE OF A NEURONThe Spinal CordIt is a part of the central nervous system%tarts from the base of the skull and extends through most of the backbone or vertebral columnThe Spinal CordIt is a cylinder of nerve tissue as thick as a finger and about &' cm long"t the center of the cord is a gray matter and surrounding it is a white matterGRAY MATTERContains the cell bodies and motor connector neuronsThe axons of the sensory neurons whose cell bodies outside the spinal cord also enter the gray matterHITE MATTERContains the axons of neurons that run lengthwise through spinal cordThe spinal cord is surrounded by the membranes called meningesComing out of the spinal cord on both sides and at regular intervals are the spinal nerve roots# The spinal nerve branch out to the different parts of the bodyIt is the link between the peripheral and nervous system and the brainThe nerve tracts that make up the white matter in the spinal cord are the pathways of information to and from the brain%ensory messages from the eyes ears and other sense organs pass upward through the spinal cord to the brain#The pathway for sensory nerves are ascending tracts# M!" signa#s from the brain $ass d%n%a"d through the spinal cord to the neurons that lead to the glands or muscleThe spinal cord also handle some information coming from thesenses and provide motor responses that do not come from the brain# This called a reflex actionA reflex is an automatic response which is controlled by the spinal cordThe messages reaches the brain after the action is doneIn some cases the message is not transmitted to the brain