transmission between neurons Flashcards
how is information transmitted between neurons
via synaptic transmission
- neurotransmitters are released from one neuron and attach to another neuron
- this initiated a reaction that ultimately results in postsynaptic potentials
what type of process is synaptic transmission
a chemical process
what neuron releases the neurotransmitter
- presynaptic
what neuron receives the neurotransmitter
- postsynaptic
what is the synapse
the junction between two neurons
- between the terminal button and membrane
- usually the membrane of the dendrite
how big is the synaptic cleft
20 nanometres
what is the process of synaptic transmission
- action potential arrives at terminal button
- calcium channel opens and calcium enters
- vesicles fuse with the membrane and calcium make the pore open
- releases neurotransmitter into the cleft - exocytosis
- neurotransmitter diffuses across the cleft and binds to the post synaptic membrane
- causes postsynaptic channel to open
- ions flow either out or in to the postsynaptic neuron - releases excitatory or inhibitory post synaptic potentials
what is binding
the neurotransmitter binds to binding site on post-synaptic membrane (lock and key)
what does the postsynaptic potential depend on
which ion channel is opened
what happens if sodium channels are opened
- sodium enters which causes depolarisation - excitatory
what happens if potassium channels are opened
- potassium leaves which causes hyperpolarisation - inhibitory
what are ionotropic receptors
- contains a binding site and an ion channel
- this opens when molecule attaches to the binding site
what are metabotropic receptors
- contains a binding site
- initiates a chain reaction that eventually opens ion channels
- requires energy
- psps slower than those produced by ionotropic receptors
how do we terminate postsynaptic potentials
- reuptake - transmitter is taken back by the presynaptic terminal via transporter molecules
- enzymatic deactivation/degradation - transmitter is broken down by an enzyme
what does excitatory mean
increases likelihood of neuron firing
what is inhibitory
- decreases the likelihood of neuron firing
what is neural integration
- summation of PSPs in control of neuron firing
what is GABA
- most abundant inhibitory neurotransmitter in CNS
- most common
what is glutamate
- most abundant excitatory neurotransmitter in CNS
- can bind to a number of receptors
- to do with learning and memory
what is Acetylcholine
- found in CNS and PNS
- specifically at neuromuscular junctions
what is dopamine
- important for motor control and reward and addiction
what is serotonin
- regulation of mood, eating and sleep
what is an antagonist
- a drug that blocks a neurotransmitter
- an example is Botulinum toxin - botox - stops release of acetylcholine and prevents muscle contraction
what is an agonist
- a drug that mimics a neurotransmitter and enhances synapse function
- an example is muscarine - imitates acetylcholine
