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T HE AVERAGE HUMAN BRAIN CONTAINS AS MANY AS 100 BILLION NERVE CELLS, OR N EURONS N EURONS VARY WIDELY IN SIZE IN SHAPE, BUT THEY ARE ALL SPECIALIZED.

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Presentation on theme: "T HE AVERAGE HUMAN BRAIN CONTAINS AS MANY AS 100 BILLION NERVE CELLS, OR N EURONS N EURONS VARY WIDELY IN SIZE IN SHAPE, BUT THEY ARE ALL SPECIALIZED."— Presentation transcript:

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3 T HE AVERAGE HUMAN BRAIN CONTAINS AS MANY AS 100 BILLION NERVE CELLS, OR N EURONS N EURONS VARY WIDELY IN SIZE IN SHAPE, BUT THEY ARE ALL SPECIALIZED TO RECEIVE AND TRANSMIT ( SEND ) INFORMATION

4 L IKE ALL CELLS, THEY ARE MADE UP OF : N UCLEUS : THE COMPLETE SET OF CHROMOSOMES AND GENES C YTOPLASM : KEEPS THE CELLS ALIVE C ELL M EMBRANE : ENCLOSES THE WHOLE CELL W HAT MAKES THEM DIFFERENT ? D ENDRITES : SHORT FIBERS THAT BRANCH OUT FROM THE CELL BODY AND PICK UP INCOMING MESSAGES A XON : S INGLE LONG FIBER EXTENDING FROM THE CELL BODY ; CARRIES OUTGOING MESSAGES TO OTHER NEURONS, MUSCLES OR GLANDS A LL NEURONS ONLY HAVE ONE AXON BUT AT THE END THEY BRANCH OFF INTO MANY TERMINAL BRANCHES

5 N ERVES : GROUP OF AXONS BUNDLED TOGETHER LIKE WIRES M YELIN S HEATH : WHITE, FATTY COVERING AROUND THE AXON P INCHED IN INTERVALS T WO F UNCTIONS : P ROVIDES INSULATION SO SIGNALS FROM ADJACENT NEURONS SO THEY DO NOT INTERFERE WITH EACH OTHER I NCREASES THE SPEED THAT A SIGNAL IS TRANSMITTED

6 S ENSORY N EURON : N EURONS THAT COLLECT MESSAGES FROM SENSE ORGANS AND CARRY THEM TO THE SPINAL CORD OR THE BRAIN M OTOR N EURONS : N EURONS THAT CARRY MESSAGES FROM THE SPINAL CORD / BRAIN TO MUSCLES AND GLANDS I NTERNEURONS (A SSOCIATION ) N EURONS : C ARRIES MESSAGES FROM ONE NEURON TO ANOTHER T HE N ERVOUS S YSTEM ALSO CONTAINS NUMEROUS G LIAL C ELLS OR GLIA G REEK WORD FOR GLUE H OLD THE NEURONS IN PLACE, PROVIDE NOURISHMENT AND WASTE PRODUCT, PREVENT HARMFUL SUBSTANCES FROM PASSING FROM THE BLOOD STREAM TO THE BRAIN, AND FORMS THE M YELIN S HEATH

7 N EURONS “ SPEAK ” WITH SIMPLE ELECTROCHEMICAL IMPULSES W HEN A NEURON IS AT REST AND NOT “ SPEAKING ” THEY ARE IN A STATE OF P OLARIZATION — THE CONDITION OF A NEURON WHEN THE INSIDES IS NEGATIVELY CHARGED OUTSIDE A GUITAR STRING THAT HAS BEEN PULLED BUT NOT RELEASED T O GENERATE A SIGNAL THE TENSION NEEDS TO BE RELEASE

8 D EPOLARIZATION : WHEN AN AREA OF THE CELL MEMBRANE IS STIMULATED ENOUGH BY MESSAGES, PORES ( CHANNELS ) ALLOW POSITIVELY CHARGED IONS COME IN ; ALLOWING THE INSIDE TO BE POSITIVE C REATES AN ELECTRICAL CHARGE, OR A NEURAL IMPULSE, THAT TRAVELS DOWN THE AXON W HEN THIS HAPPENS THE N EURON HAS “ FIRED ”— SENT A SIGNAL T HIS ENTIRE PROCESS TAKES ONLY A MILLISECOND

9 G RADED P OTENTIAL : INCOMING MESSAGES THAT CAUSE A SMALL, TEMPORARY SHIFT IN THE ELECTRICAL CHARGE LEAVING THE NEURON IN ITS POLARIZED STATE F OR A N EURON TO FIRE, GRADED POTENTIALS MUST EXCEED A CERTAIN MINIMUM THRESHOLD OF EXCITATION — LEVEL AN IMPULSE MUST EXCEED TO CAUSE A NEURON TO FIRE E ACH TIME A NEURON FIRES IT IS THE SAME STRENGTH C ALLED A LL - OR -N OTHING - L AW

10 H OWEVER, THE NEURON IS MORE LIKELY TO FIRE MORE OFTEN WHEN STIMULATED BY A STRONG SIGNAL A BSOLUTE R EFRACTORY P ERIOD : A FTER A NEURON FIRES, FOR THE NEXT THOUSANDTH OF A SECOND IT WILL NOT FIRE AGAIN REGARDLESS OF THE STRENGTH OF THE INCOMING MESSAGE ' S R ELATIVE R EFRACTORY P ERIOD : DURING THE RESTING STATE OF A CELL THE NEURON WILL ONLY FIRE IF THE INCOMING MESSAGE IS CONSIDERABLY STRONGER THAN NORMAL O THERWISE AFTER A NEURON FIRES IT RETURNS TO ITS RESTING STATE AND WAITS FOR THE NEXT INCOMING MESSAGE

11 N EURONS ARE NOT DIRECTLY CONNECTED LIKE A CHAIN, INSTEAD THERE ARE TINY GAPS — CALLED SYNAPTIC SPACE W HEN A NEURON FIRES, AN IMPULSE TRAVELS DOWN THE AXON, OUT THOUGH THE TERMINAL BRANCHES INTO A TINY SWELLING THAT LOOKS LIKE A LIGHT BULB C ALLED T ERMINAL B UTTON OR S YNAPTIC K NOB S YNAPSE : AREA COMPOSED OF THE AXON TERMINAL OF ONE NEURON, THE SYNAPTIC SPACE, AND THE DENDRITE ( CELL BODY ) OF THE NEXT NEURON

12 W HEN THE NEURAL IMPULSES REACHES THE END OF THE TERMINALS IT CAUSES THE VESICLES TO RELEASE VARYING AMOUNTS OF CHEMICALS CALLED NEUROTRANSMITTERS S YNAPTIC VESICLES : TINY BAGS IN THE TERMINAL BUTTON THAT RELEASE CHEMICALS INTO THE SYNAPSE N EUROTRANSMITTERS : CHEMICALS RELEASED BY THE SYNAPTIC VESICLES THAT TRAVEL ACROSS THE SYNAPTIC SPACE N EUROTRANSMITTERS EACH HAVE A SPECIFIC MATCHING RECEPTOR SITE ON THE OTHER SIDE OF THE SYNAPTIC CELL R ECEPTOR S ITE : LOCATION ON A RECEPTOR NEUROTRANSMITTER ; FITS LIKE A KEY INTO A LOCK O NCE THEIR JOB IS DONE THEY DETACH FROM THE RECEPTOR SITE R ECYCLED TO MAKE NEW NEUROTRANSMITTERS, OR DISPOSED IN THE BODY AS WASTE

13 T HERE ARE HUNDREDS OF NEUROTRANSMITTERS, BUT THEIR EXACT FUNCTION IS STILL UNKNOWN S OME N EUROTRANSMITTERS ARE : A CETYLCHOLINE : INVOLVED IN AROUSAL, ATTENTION, MEMORY, MOTIVATION, AND MOVEMENT. C AN LEAD TO A LZHEIMER ’ S DISEASE D OPAMINE : VARIETY OF BEHAVIORS AND EMOTIONS, INCLUDING PRESSURE. I MPLICATED IN SCHIZOPHRENIA AND P ARKINSON ’ S DISEASE S EROTONIN : REGULATES SLEEP, DREAMING, MOOD, EATING, PAIN, AND AGGRESSION I MPLICATED IN DEPRESSION E NDORPHINS : INHIBITION OF PAIN, RELEASED DURING STRENUOUS EXERCISE R ESPONSIBLE FOR “ RUNNER ’ S HIGH ”.

14 PSYCHOPHARMACOLOGY M OST PSYCHOACTIVE DRUGS AND TOXINS WORK BY EITHER BLOCKING OR ENHANCING THE TRANSMISSION OF CHEMICALS ACROSS SYNAPSES O THERS DO THE EXACT OPPOSITE ENHANCE ACTIVITY FOR NEUROTRANSMITTERS I NCREASING THE RELEASE OF TRANSMITTER S OME SUBSTANCES INTERFERE WITH THE REMOVAL OF NEUROTRANSMITTERS FROM THE SYNAPSE AFTER THEY HAVE DON ’ T THEIR JOB SO THAT THEY CAN STIMULATE RECEPTOR NEURONS E X : C OCAINE — PREVENTS DOPAMINE FROM BEING REABSORBED … LEAD TO THE EXCESS AMOUNTS OF DOPAMINE IN YOUR SYSTEM

15 NEURAL PLASTICITY N EURAL P LASTICITY : THE ABILITY OF THE BRAIN TO CHANGE IN RESPONSE TO THE EXPERIENCE F EEDBACK LOOP — EXPERIENCE LEAD TO CHANGES IN THE BRAIN, WHICH FACILITATE NEW LEARNING … WHICH LEADS TO THE BRAIN CHANGING TO ACCEPT WHAT WE NEWLY LEARNED E X : D EAF PEOPLE ’ S BRAINS HAVE SHOWN CHANGES IN THE AREAS RESPONSIBLE FOR HEARING TO REWIRED TO READ LIPS AND SIGN LANGUAGE S TUDIES DONE IN THE 1990’ S SHOWED THAT ADULT BRAINS ERE CAPABLE OF N EUROGENESIS – GROWTH OF NEW NEURONS

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