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BRAIN COMMUNICATION. IN OUR BRAINS, WE HAVE. 100 BILLION NEURONS. 13.5 MILLION NEURONS IN THE SPINAL CORD ALONE. A SINGLE NEURON MAY HAVE UP 10,000 SYNAPSES SO THERE COULD BE ABOUT 1 QUADRILLION SYNAPSES IN THE BRAIN. MESSAGES IN THE NEURONS TRAVEL THROUGH ELECTRICAL
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IN OUR BRAINS, WE HAVE 100 BILLION NEURONS
A SINGLE NEURON MAY HAVE UP 10,000 SYNAPSES SO THERE COULD BE ABOUT 1 QUADRILLION SYNAPSES IN THE BRAIN
MESSAGES IN THE NEURONS TRAVEL THROUGH ELECTRICAL AND CHEMICAL IMPULSES
NEURONS CAN FIRE OVER AND OVER AGAIN ON AN AVERAGE OF 300-400 TIMES A SECOND
CERTAIN IMPULSES MAY TRAVEL UP TO 250 MILES PER HOUR
DENDRITES (SHORT FIBERS) RECEIVE THE MESSAGE FROM A CELL WHICH IS SENT THROUGH THE CELL BODY AND THROUGH THE AXON (LONG FIBERS)
THE AXON CARRIES THE ELECTRICAL IMPULSE TO THE AXON TERMINAL WHERE NEURO- TRANSMITTERS ARE LOCATED.
SOME NEURONS MAY BE 3 FEET LONG !
NO NEURONS TOUCH EACH OTHER. THE SMALL SPACE SEPARATING THEM IS CALLED A SYNAPSE. THE ELECTRICAL MESSAGE CANNOT JUMP ACROSS THE SYNAPSE SO THE MESSAGE IS SENT THROUGH A CHEMICAL MESSAGE CALLED A NEUROTRANSMITTER.
THE CHEMICAL MESSAGE IS THEN RECEIVED BY THE DENDRITE OF THE NEXT CELL WHICH TRIGGERS AN ELECTRICAL IMPULSE THROUGH THE RECEIVING CELL
IN ADDITION, THERE ARE ABOUT ONE TRILLION GLIAL CELLS IN THE BRAIN
GLIAL CELLS DO NOT SEND ELECTROCHEMICAL SIGNALS LIKE NEURONS. THEY SUPPORT THE NEURONS IN THE FOLLOWING WAYS: THEY ARE 10 TIMES MORE NUMEROUS THAN NEURONS
GLIAL CELLS PROVIDE STRUCTURAL SUPPORT PROVIDE NUTRITIONAL SUPPORT HELP WITH CELL MAINTENANCE
NEUROTRANSMITTERS • ACETYLCHOLINE (ACH)-basic bodily processes like movement • Botulism shuts off release of ACH • DOPAMINE – control of body movement, mood (Alzheimer’s and Parkinson’s) (some schizophrenics have excess) • ENDORPHINS – relieves pain increases sense of well-being (morphine within) • SEROTONIN-plays role in mood, body temperature, sleep
WE HAVE KNOWN ABOUT ELECTRICAL MESSAGES FOR MANY YEARS, p.58 BUT OUR KNOWLEDGE OF THE CHEMICAL FUNCTIONS IS RELATIVELY NEW. SCIENTISTS HAVE IDENTIFIED OVER 300 NEUROTRANSMITTERS. SOME ARE: ACETYLCHOLINE DOPAMINE NOREPHENEPRHINE ENDORPHINS GLUTAMATE GABA (ANGL OR GLAN) SEROTONIN (DEGA Star) EXCITATORYINHIBITORY
PARTS OF THE NEURON • Draw another neuron to communicate with your neuron. • Clearly identify the dendrites, cell body, axon, axon terminal, vesicles, neurotransmitters, and synapses. • Describe the function of the sensory neuron, interneuron, and motor neuron.