synpase & neurotransmitters Flashcards
pre-synaptic neuron
axon
contact between a neuron and another neuron or its effector cell
synapse
post-synaptic neuron
dendrite or cell body
OR
cell (ex: muscle)
cells are separated by what in synpases
synaptic cleft
the predominant type of synapses
chemical synapses
chemical synapses is __directional
unidirectional
true or false. chemical synapses uses neurotransmitters
true
the properties of a chemical synapse scan be changed by the ____ of a neuron
metabolism
4 criteria of a neurotransmitter (NT)
- must be present in pre-synaptic terminal
- released upon stimulation
- NT in extracellular fluid must yield same response as synaptic event
- a removal mechanism must exist
NT active for short period of time b/c of what 3 things
enzymatic destruction
re-uptake
extracellular peptidase digestion
directly alter membrane permeability….ionotropic or metabotropic
ionotropic
ionotropic/metabotropic…..which is slow and which is fast
ionotropic = fast metabotropic = slow
produces a metabolic change in post-synaptic cell….ionotrpoic or metabotropic
metabotropic
basic overview of chemical synapses
- NT released into synaptic cleft
- binds receptor on post-synaptic effector & alters post-synaptic cell function
where is the NT synthesized
pre-synaptic cell
NT requires what 2 things
- membrane depolarization
- calcium influx
NT release involves what type of channels
voltage-gated calcium channels
Ca2+ influx into cytosol triggers what
exocytosis of vescicles
- vesicles fuse to plasma membrane - NT released into synaptic cleft
ligand gated channels (4 characteristics)
- synaptic transmission
- permeability depends on NT binding
- located on cell body and dendrites
- potentials are graded & spread decrementally
voltage-gated channels (4 characteristics)
- action potential generation
- NT release
- permeability dependent on M.P.
- potentials are “all or nothing” and propagated
synaptic potentials occur in ____
ionotropic synapses
inhibitory vs. excitory
inhibitory: hyperpolarizes (makes more than resting)
excitory: depolarizes (makes less than resting)
single nerve stimulated in rapid succession
temporal summation
several pre-synaptic neurons acting on same post-synaptic neuron stimulated simultaneously
spatial summation
whether or not an action potential is generated depends on:
- spatial or temporal summation
2. proximity of synapse to axon hillock
further from axon hillock, ____ PSP is degraded
more
synapse within cell body = closer to hillock = more influence
axosomatic
synapse with dendrite = farther from hillock = less influence
axodendritic
sum of all ion currents flowing through channels at once
synaptic current
4 properties of a fast ionotropic receptor
- channel opening is all or nothing
- channel opening depends on NT concentration (more NT=more opening)
- current flowing through channels contributes to neuron’s PSP
- currents through all channels can be summated (can add to each other or cancel each other out)
synpase between neuron & skeletal muscle fiber
neuromuscular EPSP
each motor neuron action potential causes a large EPSP in the muscle
relay synapse
a NT that:
- binds to a ligand-gated Na+/K+ membrane channel
- increases membrane permeability to Na+ and K+
- depolarizes membrane
- makes Na+ flow in more quickly than K+ flows out
acetylcholine
fast EPSP that is small in magnitude but results in membrane depolarization due to ligand-gated Na+/K+ channels
Type 1 synapse
neurotransmitters in Type 1 synapse
glutamate
type 1 synapse needs what?
summation
slow IPSP that is inhibitory and involves opening of ligand-gated chloride channels
type 2 synapse
neurotransmitters in type 2 synapse
GABA, glycine
