Neurons, neurotransmitters Neurons, neurotransmitters and other stuff we did last and other stuff we did last

term…term…

Psychology 2617Psychology 2617

IntroductionIntroduction

This is mostly review for those of you that This is mostly review for those of you that took 2606took 2606

The nervous system is made up, basically, The nervous system is made up, basically, of two types of cellsof two types of cellsNeuronsNeurons

Do the communicatingDo the communicating

Glial CellsGlial CellsSupport functionsSupport functions

Some key neuron factsSome key neuron facts

One axon, many dendrites (usually, One axon, many dendrites (usually, multipolar neurons have more than one multipolar neurons have more than one axon)axon)

Dendrite -> cell body -> axonDendrite -> cell body -> axonAxons transmit informationAxons transmit informationDendrites receive informationDendrites receive informationDendrites can grow and changeDendrites can grow and change

Make connections to more axonsMake connections to more axonsMight be the basis of learningMight be the basis of learning

Electrical activity of the neuronElectrical activity of the neuron

Resting potentialResting potentialAbout -70 mVAbout -70 mVSelectively allowing certain ions inSelectively allowing certain ions inWith stimulation Na+ is allowed inWith stimulation Na+ is allowed in

Action potentialAction potentialChanges in one area lead to changes in Changes in one area lead to changes in

anotheranotherChemical to electrical, very coolChemical to electrical, very cool

The action potentialThe action potential

Resistance and myelin affect transmission Resistance and myelin affect transmission raterate

Less resistance with a big axonLess resistance with a big axonNormally you have a resting potential Normally you have a resting potential

because a process called Active Transport because a process called Active Transport pump ouf NA+ and pulls K+ in (3:2) so you pump ouf NA+ and pulls K+ in (3:2) so you get a negative charge across the cell get a negative charge across the cell membranemembrane

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, Na pump to sort of stop, Na gets in, K goes outgets in, K goes out

Sort of reversed laterSort of reversed later

Biochemical ActivityBiochemical Activity

Otto Loewi did a cool experiment in 1921Otto Loewi did a cool experiment in 1921Simulated the vagus nerve is a frog’s heartSimulated the vagus nerve is a frog’s heartSlowed the heart downSlowed the heart downWashed heart with solution, collected Washed heart with solution, collected

solutionsolutionPoured 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 vagusstoffAcetylcholineAcetylcholineLater stimulated heart rate, similar methodLater stimulated heart rate, similar methodEnded up with a sped up heartEnded up with a sped up heartEpinephrineEpinephrine

The SynapseThe Synapse

Gap between the axon and the dendriteGap between the axon and the dendriteNeurotransmitters are released across this Neurotransmitters are released across this

gapgapSometimes, if all of the transmitter isn’t Sometimes, if all of the transmitter isn’t

absorbed it is taken back up, this is known absorbed it is taken back up, this is known as reuptakeas 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 of a Is the excitatory vs. inhibitory nature of a synapse due to shape?synapse due to shape?

ProbablyProbablyGABA synapses are inhibitory, have less GABA synapses are inhibitory, have less

post synaptic thickeningpost synaptic thickeningGlutamate synapses have more Glutamate synapses have more

thickening, more vesiclesthickening, more vesiclesThere are 7 types of synapsesThere are 7 types of synapses

The Seven Steps in The Seven Steps in NeurotransmissionNeurotransmission

SynthesisSynthesisStorageStorageReleaseReleaseReceptor interactionReceptor interaction InactivationInactivationReuptakeReuptakeDegradationDegradation

The NeurotransmittersThe Neurotransmitters

Basically, five conditions must be met Basically, five conditions must be met before we call something a before we call something a neurotransmitterneurotransmitterPresent in terminalPresent in terminalReleased on firingReleased on firingPlacing substance or organ emulates firingPlacing substance or organ emulates firingUptake for inactivationUptake for inactivation Inactivation blocks stimulationInactivation blocks stimulation

The NeurotransmittersThe Neurotransmitters

Acetylcholine (Ach)Acetylcholine (Ach)MonoaminesMonoamines

CatecholaminesCatecholaminesNorepinephrine (NE)Norepinephrine (NE)Epinephrine (E)Epinephrine (E)Dopamine (DA)Dopamine (DA)

IndoleamineIndoleamineSeretonin (5-Ht)Seretonin (5-Ht)

OthersOthersHistamine (H)Histamine (H)

More neurotransmittersMore neurotransmitters

Amino AcidsAmino AcidsGlutamate (universally excitatory)Glutamate (universally excitatory)GABA (universally inhibitory)GABA (universally inhibitory)GlycineGlycineProlineProline

PeptidesPeptidesSubstance PSubstance P

Finally….Finally….

Morphine like substancesMorphine like substancesEndorphinsEndorphinsEnkephalinsEnkephalins

Other peptidesOther peptides InsulinInsulinProlactinProlactinHGHHGHVasopressinVasopressin

distributiondistribution

Ach is all over the place, cortex, RAS, muscular Ach is all over the place, cortex, RAS, muscular system etcsystem etc

5Ht is also all over the place but originates in the 5Ht is also all over the place but originates in the nuclei of the raphe which project to the nuclei of the raphe which project to the cerebellumcerebellum

NE mostly in lucus ceruleusNE mostly in lucus ceruleus DA substantia nigra and reward systemDA substantia nigra and reward system GABA and glutamate are all over the place, GABA and glutamate are all over the place,

maybe 1/3 of all synapses are GABAmaybe 1/3 of all synapses are GABA Opiates in VTAOpiates in VTA

ReceptorsReceptors

Transmitters bind to receptorsTransmitters bind to receptorsSort of like a lock and a keySort of like a lock and a keyBinding siteBinding site Ion channelIon channelOne neuron (usually) has only one type of One neuron (usually) has only one type of

receptorreceptorGreat 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, cerebellumCommunication is neuralCommunication is neural

Peripheral Nervous system (PNS)Peripheral Nervous system (PNS)Nerves that make you move basicallyNerves that make you move basicallyCommunication is neuralCommunication is neural

Autonomic nervous systemAutonomic nervous system