WEBVTT 00:01.166 --> 00:06.367 position:10% line:85% size:80% >>> THE NERVOUS SYSTEM IS THE BODY'S WIRING, A NETWORK THAT 00:06.367 --> 00:10.567 position:10% line:85% size:80% STRETCHES FROM OUR BRAIN ALL THE WAY TO OUR TOES. 00:10.567 --> 00:13.033 position:10% line:85% size:80% THE NERVOUS SYSTEM IS DIVIDED INTO THREE PARTS. 00:13.033 --> 00:14.934 position:10% line:85% size:80% THE CENTRAL NERVOUS SYSTEM INCLUDES THE BRAIN AND THE 00:14.934 --> 00:17.266 position:10% line:85% size:80% SPINAL CORD. 00:17.266 --> 00:19.800 position:10% line:85% size:80% THE SPINAL CORD IS A BUNDLE OF NERVE CELLS STARTING AT 00:19.800 --> 00:21.934 position:10% line:85% size:80% THE BASE OF THE BRAIN. 00:21.934 --> 00:24.467 position:10% line:85% size:80% AND IT'S PROTECTED BY THE VERTEBRAS OF YOUR BACK BONE. 00:24.467 --> 00:27.800 position:10% line:85% size:80% THE NEXT PART IS THE PERIPHERAL NERVOUS SYSTEM. 00:27.800 --> 00:31.166 position:10% line:85% size:80% THERE ARE 31 PAIRS OF NERVES COMING OUT BETWEEN THE 00:31.166 --> 00:32.200 position:10% line:85% size:80% VERTEBRAS INTO THE BODY. 00:32.200 --> 00:35.800 position:10% line:85% size:80% THEY BRANCH OUT THROUGHOUT THE WHOLE BODY. 00:35.800 --> 00:38.934 position:10% line:85% size:80% ALL YOUR SENSORY ORGANS, YOUR EYES, EARS, NOSE, SKIN, AND 00:38.934 --> 00:41.533 position:10% line:85% size:80% TONGUE ALL FEED INFORMATION TO THE BRAIN THROUGH THE 00:41.533 --> 00:44.000 position:10% line:85% size:80% PERIPHERAL NERVOUS SYSTEM. 00:44.000 --> 00:48.200 position:10% line:85% size:80% AND THE THIRD PART IS THE AUTONOMIC NERVOUS SYSTEM. 00:48.200 --> 00:50.467 position:10% line:85% size:80% THIS SYSTEM DEALS WITH THE INVOLUNTARY ACTIONS OF OUR 00:50.467 --> 00:51.000 position:10% line:85% size:80% BODY. 00:51.000 --> 00:54.166 position:10% line:85% size:80% THINGS LIKE BREATHING, YOUR HEART BEATING, OR EVEN 00:54.166 --> 00:58.400 position:10% line:85% size:80% DIGESTING FOOD. 00:58.400 --> 01:01.734 position:10% line:85% size:80% >> IT'S CALLED THE AUTONOMIC OR INVOLUNTARY SYSTEM BECAUSE YOU 01:01.734 --> 01:04.000 position:10% line:85% size:80% DON'T HAVE TO THINK ABOUT IT, YOUR BRAIN AND NERVES JUST KEEP 01:04.000 --> 01:06.567 position:10% line:85% size:80% YOUR BODY FUNCTIONING. 01:06.567 --> 01:09.300 position:10% line:85% size:80% >> THE NERVOUS SYSTEM IS MADE UP OF MORE THAN 100 BILLION 01:09.300 --> 01:12.166 position:10% line:85% size:80% NERVE CELLS. 01:12.166 --> 01:14.166 position:10% line:85% size:80% EACH CELL HAS THREE MAIN PARTS. 01:14.166 --> 01:16.934 position:10% line:85% size:80% THE CELL BODY OR NUCLEUS. 01:16.934 --> 01:21.834 position:10% line:85% size:80% DENDRITES, LONG THIN BRANCHES THAT GROW OUT OF THE CELL BODY. 01:21.834 --> 01:24.000 position:10% line:85% size:80% AND AXONS, SLIGHTLY LONGER THAN THICKER BRANCHES THAT 01:24.000 --> 01:26.934 position:10% line:85% size:80% ALSO COME OUT OF THE CELL BODY. 01:26.934 --> 01:31.734 position:10% line:85% size:80% A MESSAGE OR IMPULSE MOVES BETWEEN CELLS. 01:31.734 --> 01:34.633 position:10% line:85% size:80% THIS ELECTRICAL CHARGE TRAVELS INTO CELL BODY VIA THE 01:34.633 --> 01:39.100 position:10% line:85% size:80% DENDRITES AND OUT OF THE CELL BODY THROUGH THE AXONS. 01:39.100 --> 01:42.800 position:10% line:85% size:80% NERVE CELLS ARE SEPARATED BY TINY GAPS CALLED SYNAPSES. 01:42.800 --> 01:46.000 position:10% line:85% size:80% WHEN AN ELECTRICAL IMPULSE REACHES THE SYNAPSES, THE 01:46.000 --> 01:49.800 position:10% line:85% size:80% CELLS RELEASE A CHEMICAL KNOWN AS NEUROTRANSMITTER. 01:49.800 --> 01:53.834 position:10% line:85% size:80% THE MESSAGE JUMPS OR FLOWS ACROSS THE GAP WITH THE 01:53.834 --> 01:55.567 position:10% line:85% size:80% NEUROTRANSMITTER TO SPECIAL LANDING SITES KNOWN AS 01:55.567 --> 01:57.500 position:10% line:85% size:80% RECEPTORS. 01:57.500 --> 01:59.567 position:10% line:85% size:80% >> JUST LIKE A RELAY RACE. 01:59.567 --> 02:02.834 position:10% line:85% size:80% NERVE CELLS PASS IMPULSES FROM ONE CELL TO THE NEXT. 02:02.834 --> 02:06.000 position:10% line:85% size:80% >> AND NERVE CELLS ARE REALLY FAST. 02:06.000 --> 02:08.200 position:10% line:85% size:80% IT ONLY TAKES ABOUT ONE- THOUSANDth OF A SECOND FOR A 02:08.200 --> 02:10.567 position:10% line:85% size:80% MESSAGE TO JUMP FROM CELL TO CELL. 02:10.567 --> 02:13.667 position:10% line:85% size:80% >> WHILE YOUR BRAIN GENERALLY CONTROLS A LOT OF WHAT'S GOING 02:13.667 --> 02:15.400 position:10% line:85% size:80% ON IN YOUR NERVOUS SYSTEM, IT DOESN'T CONTROL THE BODY'S 02:15.400 --> 02:17.667 position:10% line:85% size:80% EVERY MOVEMENT. 02:17.667 --> 02:19.800 position:10% line:85% size:80% IF YOU TOUCH SOMETHING HOT, THE SENSORY NERVE CELLS SEND 02:19.800 --> 02:22.000 position:10% line:85% size:80% A SIGNAL TO THE MUSCLES TO TELL THEM TO MOVE. 02:22.000 --> 02:22.834 position:10% line:85% size:80% >> OUCH! 02:22.834 --> 02:27.667 position:10% line:85% size:80% >> THAT AUTOMATIC MOVEMENT IS CALLED A REFLEX REACTION. 02:27.667 --> 02:30.734 position:10% line:85% size:80% DIFFERENT NERVE CELLS DO DIFFERENT THINGS IN YOUR BODY. 02:30.734 --> 02:33.367 position:10% line:85% size:80% SOME DETECT CHANGES IN LIGHT SO YOU BLINK. 02:33.367 --> 02:35.000 position:10% line:85% size:80% OR SMELLS SO YOU SNIFF. 02:35.000 --> 02:37.166 position:10% line:85% size:80% OR TASTE SO YOU LICK. 02:37.166 --> 02:40.367 position:10% line:85% size:80% OR SOUND SO YOU HEAR. 02:40.367 --> 02:42.200 position:10% line:85% size:80% OR TEMPERATURES SO YOU SWEAT. 02:42.200 --> 02:45.667 position:10% line:85% size:80% OR PRESSURE SO YOU MOVE. 02:45.667 --> 02:50.533 position:10% line:85% size:80% >> YOU HAVE MORE THAN A MILLION STRETCH SENSORS IN OUR JOINTS, 02:50.533 --> 02:54.467 position:10% line:85% size:80% MUSCLES, SKIN AND NERVES TO CONSTANTLY MONITOR YOUR BODY 02:54.467 --> 02:57.233 position:10% line:85% size:80% POSITION. 02:57.233 --> 03:00.633 position:10% line:85% size:80% YOUR NERVOUS SYSTEM NEVER RESTS. 03:00.633 --> 03:03.934 position:10% line:85% size:80% AND UNLIKE OTHER CELLS, THE BODY'S NERVES RARELY GET 03:03.934 --> 03:06.000 position:10% line:85% size:80% REPAIRED OR RENEWED IF DAMAGED.