Nerve impulse transmission Flashcards
action potential
Wave of depolarization that travels between excitable cells
synaptic vesicles are located _____
at the synapse full of neurotransmitters and are recycled
acetylcholine
neurotransmitter that triggers muscle contractions
How do synaptic vesicles release neurotransmitters?
- ) Attach to docking protein
- ) Use v- and t-SNAREs to fuse with the plasma membrane
- ) Release all of its neurotransmitters
* * does not necessarily happen in all cases
Role of Ca2+
an increase in Ca2+ concentration in the cytosol caused by the depolarization from the action potential triggers release of synaptic vesicles
acetylcholine receptor
- When opened, it allows Na+ through
- Na+ depolarizes the muscle cell and causes a muscle contraction
GABA receptor
ligand-gated chloride channel that dampens effect of depolarization because the resting potential of Cl- is close to the cell’s resting potential
Tranquilizers
enhance inhibitory neurotransmitters (ex: Valium)
After neurotransmitters are released ___
NTs must be removed:
- NTs are taken back by presynaptic neuron
- Acetylcholine is degraded in the synaptic cleft
Reducing reuptake
Causes the effect of the NTs to be amplified (coke, SSRIs, nerve gas)
Why aren’t synapses fused?
Complex information processing wouldn’t be possible because it would limit how many synapses the cell has and the ability to receive signals from many different cells.
Temporal summation
multiple rounds of NT released from the same synapse
Spatial summation
multiple nearby synapses fire at the same time and increase potential in nearby cells
Electrical synapses
- Gap junctions have connexons that form a channel between two cells
- synchonous firing for primitive functions
- close for self protection
acetylcholine receptor shape
5 subunits with linked alpha-helices that block the channel when acetylcholine is not present
