Transmission Between Neurons Flashcards
An excitatory input is called…
Excitatory post synaptic potential EPSP
The synapse is…
A small gap between neurons
Electron microscopes let us see individual synapses
A neurotransmitter is…
A chemical signal carrying information between neurons. It is released from pre synaptic neuron to the post synaptic neuron
A vesicle is…
A sack full of neurotransmitter found in each bouton/terminal
The synapse in action…
1) AP arrives at the bouton of presynaptic cell which opens the calcium ca2+ ion channels
2) calcium causes vesicles to fuse with cell membranes (exocytosis) and neurotransmitter is released into synaptic cleft
3) the neurotransmitter diffuses across the cleft and binds to receptor on the post synaptic neurons which can trigger a new AP
Neurotransmitter can be removed from the synaptic cleft by…
Diffusion
Reuptake - transport moves neurotransmitter back into presynaptic neuron which uses energy
Deactivation - enzyme breaks neurotransmitter down into parts, which happens in the synaptic cleft
Raman Y Cajal
Nobel prize 1906
Proposed synapses
Bernard Katz
Nobel prize 1970
Synapse chemical
Inhibitory neurotransmitter
GABA
Excitatory neurotransmitters
Glutamate
Acetylcholine
Serotonin
Dopamine
Non primary neurotransmitter
Neuro modulators - modulate transmission of information
Action potentials are…
Generated in the axon hillock. They move down the axon and their amplitude is always the same
Several action potentials arrive at the dendrite which triggers a change in the postsynaptic membrane causing an electrical change in membrane potential
Acetylcholine
Is found in the brain and neuromuscular junction. It binds to nicotinic receptors in the post synaptic neuron. It increases the membrane potential
It is fast (ionotropic) and excitatory
Nicotine also binds at nicotinic receptors
A neuromuscular junction is…
Where the neuron joins muscle to activate the muscle
Curare blocks the action of ACh here and paralyses prey
Glutamate
Found in the CNS and the brain. It is the main carrier of excitatory neurotransmission
ACh is a primary neuromodulator here
Serotonin
Is found in the brain
It binds to receptor which triggers G protein which activates a 2nd messenger which opens on channels
It is slow (metabotropic) and excitatory
GABA (gamma aminobutyric acid)
Is found throughout the brain. Binds to fast and slow GABA receptors which opens Cl- ion channels and decrease membrane potential.
GABA inhibits neurons and reduces the likelihood to fire at AP
Neurotransmitters and drugs
Nicotine - nicotinic acetylcholine receptors Alcohol - GABA serotonin dopamine NMDA amphetamines and cocaine - dopamine Prozac - serotonin L-Dopa - dopamine Diazepam - GABA Dinepezil - acetylcholine
Excitation - glutamate, serotonin
Driven by osmosis gradient
Sodium and calcium enter neuron. EPSP. Influx of sodium - membrane potential increases and AP more likely
Inhibition - GABA
Driven by osmosis gradient
Potassium leaves and Chloride enters. IPSP. Influx of chloride and membrane potential decreases making AP less likely
Donald O. Hebb
Axon of cell A near enough to excited cell B and often takes part in firing it - growth process or metabolic change takes place in one or both cells so A’s efficiency, as a cell firing B, increases
Hebbian learning rule
Synchronised activation of two neural pathways leads to strengthening of the previously ineffective one by enhancing their synaptic efficiency or gain
Long term potentiation is a prominent mechanism for associative learning
