Lecture 7 Flashcards
T or F? Exc or Inh inputs can be received in a dendrite.
T
Why is the AP threshold lowest at the trigger zone?
more Na channels
T or F? Exc or ing inputs decrease in time.
T
T or F? The threshold for each cell is constant for all surfaces of the cell.
F. Lower threshold at the trigger zone (more Na channels)
What determines relative efficacy of input to create an AP?
proximity to synapse
T or F? A distal synapses with the same level of exc input will have a greater impact than one that is more proximal.
F. vice versa
How are synaptic potentials integrated?
spatially and temporally
These are the dominant player after threshold is reached?
Voltage gated Na channels
EPSP’s are used in reference to __ and EPP’s are used in reference to:
CNS, NMJ
EPSP’s are triggered by ___ and EPPs are triggered by:
glutamate, AcH (and glutamate)
Why can synaptic pot’s increase temporal?
build up of Ca bc they don’t have time to close completely
The buildup of _____ leads to temporal summation of synaptic potentials:
Ca
There ___ times more Ca outside the cell than inside.
10,000
Why will low freq stimulation generate the same size EPSP?
Ca had time to return to baseline
T or F? Spatial and temp can only happen with EPSP .
F. Both EPSP and IPSP
Can inhibition be presyn, postsyn, or either.
either
Postsynaptic inhibition is mediated by:
GABA(aR)
What molecule is used in postsynaptic inhibition?
Cl- (GABA is a chloride channel)
What affect postsyn inhibition have on an EPSC?
shunt and reduce the efficacy
Where are postsyn inhibitory synapses located?
dendritic shaft of cell body near AP trigger zone
T or F? Inhibitory synapses can only work locally.
T
T or F? Inhibitory synapses can decrease the efficacy of excitatory inputs over the whole cell globally.
T
Where does presynaptic inhibition usually occurs?
at axon-axonic synapse
What does it mean if you decrease the efficacy of an EPSP?
size decreases
What type of channel does presynaptic inhibition target?
Ca channels
What type of receptor is involved with presynaptic inhibition?
GABA(b)
What type of receptor is GABA(b)?
metabotropic receptor
What affect will GABA(b) receptor have on ion levels?
decrease Ca channels
T or F? Presynaptic inhibition increases the amount of T release.
F. Decreases
Another term for amount of T released:
quantal content
In which pathways does presynaptic inhibition play a prominent role?
sensory system pathways
presynaptic inhibition plays this role in sensory system pathways:
habituation
Define habituation:
filter out non-meaningful info (noise, monotonic tones in auditory pathway)
Principle T of presynaptic inhibition:
GABA
These neurotransmitters regulate diverse populations of neurons:
neuromodulators
Each T has only one specific type of receptor.
F. Can have diff receptors
T or F? The presynaptic, inhibitory metabortropic GABA receptor is voltage dependent.
T
Presynaptic uses GABA__ and postsynaptic uses GABA___.
b, a
To where do inhibitory interneurons attach?
to the sensory afferent that is attached to the neuron of interest
T or F? Inhibitory interneurons can only be effective if they are stimulated after the sensory afferent.
F. must be stimulated before
Inhibitory interneurons inhibit the initial synapse by releasing:
GABA
The release of GABA by the interneuron has what affect?
this inhibits the release of glutamate, leading to a smaller EPSP
How does GABA(b) affect the channels of the sensory afferent neuron?
deactivation of Ca channels and activation of Ka channels
T or F? GABA(b)R’s increase the rate of cell depolarization.
F. increase the rate of repolarization
What affect will GABA(b)R’s have on T release?
decrease it
monosynaptic pathway is exc/ inh?
exc
Bisynaptic pathway is exc/inh?
inh
The Renshaw cell is mediated by:
‘slow’ and ‘fast’ postsynaptic transmission
Affect of RC on weakly excited MN in motor center:
inhibits
Affect of RC on strongly excited MN in motor center:
decreases firing rate (fine tunes muscle control)
This is involved in fine tune muscle control:
Renshaw cell
T or F? Inhibitiory interneuron are glycinergic and induces EPSP’s.
F. 1st part true, but induce IPSP’s
This can lead to prolonged m. contraction:
No feedback control
Too much AcH released will activate (this type of) receptors through ________ that will either release AcH (cholinergic) to activate nicotinic receptors at NMJ or release AcH to activate muscarinic at the interneuron (Renshaw cell)
muscarinic, axon collaterals
What kind of receptors are at the NMJ?
nicotinic (AcH)
What type of receptor are at the interneuronal junction?
muscaarinic
T or F? Muscarinic is ionotropic.
F.
What affect will muscarinic receptors have on interneurons?
decrease K channels and increase the firing
acetylcholine receptors that form G protein-receptor complexes:
muscarinic AcH receptors
T or F? nAChRs and mAChRs are both used in the ANS.
T
What affect will mAChR have on the RC cell?
stimulatory increase
The exc RC cell will release this once excited
glycine (feedback mechanism)
Excitation of interneuron leads to:
inhibition
Fast synaptic transmission will always activate:
the intrinsic ion channels
Fast synaptic transmission can be exc, inh, or either?
either
___ is involed in the fast pathway and ___ is involved in the slow pathway.
gly, AcH
Branch off of a neuron that projects back to the neuron itself:
axon collateral
What is the relationship between capacitance and resistance?
inversely related (check)
