Brains, Synapses and Neurotransmitters Psychology 3506.
-
Upload
godfrey-morgan-carter -
Category
Documents
-
view
233 -
download
1
Transcript of Brains, Synapses and Neurotransmitters Psychology 3506.
Brains, Synapses and Brains, Synapses and NeurotransmittersNeurotransmitters
Psychology 3506Psychology 3506
IntroductionIntroduction
Well, the book is called Drugs and Well, the book is called Drugs and Behaviour, so, we had better know Behaviour, so, we had better know how the nervous system workshow the nervous system works
The nervous system is made up, The nervous system is made up, basically, of two types of cellsbasically, of two types of cells• NeuronsNeurons
Do the communicatingDo the communicating
• Glial CellsGlial Cells Support functionsSupport functions
Some key neuron factsSome key neuron facts
One axon, many dendritesOne axon, many dendrites Dendrite -> cell body -> axonDendrite -> cell body -> axon Axons transmit informationAxons transmit information Dendrites receive informationDendrites receive information Dendrites can grow and changeDendrites can grow and change
• Make connections to more axonsMake connections to more axons• Might be the basis of learningMight be the basis of learning
Electrical activity of the neuronElectrical activity of the neuron
Resting potentialResting potential• About -70 mVAbout -70 mV• Selectively allowing certain ions inSelectively allowing certain ions in• With stimulation Na+ is allowed inWith stimulation Na+ is allowed in
Action potentialAction potential• Changes in one area lead to changes in Changes in one area lead to changes in
anotheranother• Chemical to electrical, very coolChemical to electrical, very cool
The action potentialThe action potential
Resistance and myelin affect Resistance and myelin affect transmission ratetransmission rate
Less resistance with a big axonLess resistance with a big axon Normally you have a resting potential Normally you have a resting potential
because a process called Active because a process called Active Transport pump ouf NA+ and pulls Transport pump ouf NA+ and pulls K+ in (3:2) so you get a negative K+ in (3:2) so you get a negative charge across the cell membranecharge across the cell membrane
The Sodium Potassium PumpThe Sodium Potassium Pump
Active transport takes Active transport takes energyenergy
Easier encoding?Easier encoding? Faster reaction?Faster reaction? An Action potential An Action potential
happens when happens when stimulation causes the stimulation causes the pump to sort of stop, pump to sort of stop, Na gets in, K goes outNa gets in, K goes out
Sort of reversed laterSort of reversed later
Biochemical ActivityBiochemical Activity
Otto Loewi did a cool experiment in Otto Loewi did a cool experiment in 19211921
Simulated the vagus nerve is a frog’s Simulated the vagus nerve is a frog’s heartheart
Slowed the heart downSlowed the heart down Washed heart with solution, collected Washed heart with solution, collected
solutionsolution Poured solution on a second heartPoured solution on a second heart It slowed!!!!It slowed!!!!
Loewi and his frogsLoewi and his frogs
Called the substance vagusstoffCalled the substance vagusstoff AcetylcholineAcetylcholine Later stimulated heart rate, similar Later stimulated heart rate, similar
methodmethod Ended up with a sped up heartEnded up with a sped up heart EpinephrineEpinephrine
The SynapseThe Synapse
Gap between the axon and the Gap between the axon and the dendritedendrite
Neurotransmitters are released Neurotransmitters are released across this gapacross this gap
Sometimes, if all of the transmitter Sometimes, if all of the transmitter isn’t absorbed it is taken back up, isn’t absorbed it is taken back up, this is known as reuptakethis is known as reuptake
There is lots of variation in synapsesThere is lots of variation in synapses Some are inhibitorySome are inhibitory Some are excitatorySome are excitatory
More about synapsesMore about synapses
Is the excitatory vs. inhibitory nature Is the excitatory vs. inhibitory nature of a synapse due to shape?of a synapse due to shape?
ProbablyProbably GABA synapses are inhibitory, have GABA synapses are inhibitory, have
less post synaptic thickeningless post synaptic thickening Glutamate synapses have more Glutamate synapses have more
thickening, more vesiclesthickening, more vesicles There are 7 types of synapsesThere are 7 types of synapses
The Seven Steps in The Seven Steps in NeurotransmissionNeurotransmission
SynthesisSynthesis StorageStorage ReleaseRelease Receptor interactionReceptor interaction InactivationInactivation ReuptakeReuptake DegradationDegradation
The NeurotransmittersThe Neurotransmitters
Basically, five conditions must be Basically, five conditions must be met before we call something a met before we call something a neurotransmitterneurotransmitter• Present in terminalPresent in terminal• Released on firingReleased on firing• Placing substance or organ emulates Placing substance or organ emulates
firingfiring• Uptake for inactivationUptake for inactivation• Inactivation blocks stimulationInactivation blocks stimulation
The NeurotransmittersThe Neurotransmitters
Acetylcholine (Ach)Acetylcholine (Ach) MonoaminesMonoamines
• CatecholaminesCatecholamines Norepinephrine (NE)Norepinephrine (NE) Epinephrine (E)Epinephrine (E) Dopamine (DA)Dopamine (DA)
• IndoleamineIndoleamine Seretonin (5-Ht)Seretonin (5-Ht)
• OthersOthers Histamine (H)Histamine (H)
More neurotransmittersMore neurotransmitters
Amino AcidsAmino Acids• Glutamate (universally excitatory)Glutamate (universally excitatory)• GABA (universally inhibitory)GABA (universally inhibitory)• GlycineGlycine• ProlineProline
PeptidesPeptides• Substance PSubstance P
Finally….Finally….
Morphine like substancesMorphine like substances• EndorphinsEndorphins• EnkephalinsEnkephalins
Other peptidesOther peptides• InsulinInsulin• ProlactinProlactin• HGHHGH• VasopressinVasopressin
ReceptorsReceptors
Transmitters bind to receptorsTransmitters bind to receptors Sort of like a lock and a keySort of like a lock and a key Binding siteBinding site Ion channelIon channel One neuron (usually) has only one One neuron (usually) has only one
type of receptortype of receptor Great place for drug interactionGreat place for drug interaction
The Nervous systemThe Nervous system
Central Nervous system (CNS)Central Nervous system (CNS)• Brain, spinal column, cerebellumBrain, spinal column, cerebellum• Communication is neuralCommunication is neural
Peripheral Nervous system (PNS)Peripheral Nervous system (PNS)• Nerves that make you move basicallyNerves that make you move basically• Communication is neuralCommunication is neural
Autonomic nervous systemAutonomic nervous system