Brains, Synapses and Neurotransmitters Psychology 3506

Brains, Synapses and NeurotransmittersPsychology 3506

IntroductionWell, the book is called Drugs and Behaviour, so, we had better know how the nervous system worksThe nervous system is made up, basically, of two types of cellsNeuronsDo the communicatingGlial CellsSupport functions

Some key neuron factsOne axon, many dendritesDendrite -> cell body -> axonAxons transmit informationDendrites receive informationDendrites can grow and changeMake connections to more axonsMight be the basis of learning

Electrical activity of the neuronResting potentialAbout -70 mVSelectively allowing certain ions inWith stimulation Na+ is allowed inAction potentialChanges in one area lead to changes in anotherChemical to electrical, very cool

The action potentialResistance and myelin affect transmission rateLess resistance with a big axonNormally you have a resting potential because a process called Active Transport pump ouf NA+ and pulls K+ in (3:2) so you get a negative charge across the cell membrane

The Sodium Potassium PumpActive transport takes energyEasier encoding?Faster reaction?An Action potential happens when stimulation causes the pump to sort of stop, Na gets in, K goes outSort of reversed later

Biochemical ActivityOtto Loewi did a cool experiment in 1921Simulated the vagus nerve is a frogs heartSlowed the heart downWashed heart with solution, collected solutionPoured solution on a second heartIt slowed!!!!

Loewi and his frogsCalled the substance vagusstoffAcetylcholineLater stimulated heart rate, similar methodEnded up with a sped up heartEpinephrine

The SynapseGap between the axon and the dendriteNeurotransmitters are released across this gapSometimes, if all of the transmitter isnt absorbed it is taken back up, this is known as reuptake

There is lots of variation in synapsesSome are inhibitorySome are excitatory

More about synapsesIs the excitatory vs. inhibitory nature of a synapse due to shape?ProbablyGABA synapses are inhibitory, have less post synaptic thickeningGlutamate synapses have more thickening, more vesiclesThere are 7 types of synapses

The Seven Steps in NeurotransmissionSynthesisStorageReleaseReceptor interactionInactivationReuptakeDegradation

The NeurotransmittersBasically, five conditions must be met before we call something a neurotransmitterPresent in terminalReleased on firingPlacing substance or organ emulates firingUptake for inactivationInactivation blocks stimulation

The NeurotransmittersAcetylcholine (Ach)MonoaminesCatecholaminesNorepinephrine (NE)Epinephrine (E)Dopamine (DA)IndoleamineSeretonin (5-Ht)OthersHistamine (H)

More neurotransmittersAmino AcidsGlutamate (universally excitatory)GABA (universally inhibitory)GlycineProlinePeptidesSubstance P

Finally.Morphine like substancesEndorphinsEnkephalinsOther peptidesInsulinProlactinHGHVasopressin

ReceptorsTransmitters bind to receptorsSort of like a lock and a keyBinding siteIon channelOne neuron (usually) has only one type of receptorGreat place for drug interaction

The Nervous systemCentral Nervous system (CNS)Brain, spinal column, cerebellumCommunication is neuralPeripheral Nervous system (PNS)Nerves that make you move basicallyCommunication is neuralAutonomic nervous system