electrical and chemical synapses

unlike electrical synapses, chemical synapses do not exist in [blank] junctions containing connexins

gap

electrical synapses dominate non-neural cells such as astrocytes and at [blank] embryonic stages

early

[blank] synapses dominate the mature nervous system

chemical

the time delay of hyperpolarizing inhibition indicated that synaptic transmission is mediated by [blank]

chemicals

inhibitory gabaergic interneurons are [blankly] coupled

electrically

electrical synapses interconnect interneurons of similar type but [blank] cells not coupled at all

excitatory

[blanks] must be within about 200 um and each is connected to about 20 others, and exist coupled in all layers of the neocortex

interneurons

difficult to record from two closely spaced GABAergic interneruons intracellularly in-vivo, even lower to record from same sub-type, probability is < [x]

0.04 (0.2×0.2)

[blank] synapse pores are pairs of hemichannels with connexin hexamers that form plaques called gap junctions

electrical

the gap of intracellular space in electrical synapses is only [x] nm giving nearly no delay (0.1ms)

2

[blank] subtypes of connexins have been identified so far and are named according to molecular weight

20

astrocytes express [blank], Cx30 and Cx26

Cx43

[blanks] express Cx47, Cx32 and 29

oligodendrocytes

neurons express [blank], Cx45 and maybe Cx57, this one is exclusively neuronal and the main neuronal connexin

Cx36

[blanks] only have pannexins while vertebrates have both pannexins and connexins

invertebrates

gap junctions such as Cx36 are permeable to small [blank] molecules such as IP3, Ca2+

organic

electrical synapse PSPs are similar in size but more [blank] than chemical PSPs

stable

electrical connections behave like [blank] filters, which are frequency dependent

low-pass

fewer than [blank] of the junction channels are open at any given time which gives room for regulation

half

electrical synapses allow for [blank] between coupled cells, especially interneurons

synchrony

electrical synapses are essentially [blank] conductors that transmit both subthreshold and spike signals

bidirectional

[blank] synapses are specialized junctions that transfer nerve impulse information from a presynaptic membrane to a postsynaptic membrane using neurotransmitters

chemical

the [blank] components of chemicals synapses are presynaptic vesicles and postsynaptic receptors, located between 20-50 nms away

structural

chemical synapses are unidirectional and have significant synaptic [blank], at least 0.3 ms but usually 1-5 ms or longer

delay

Gray’s type I synapse, AKA the asymmetric synapse, generally contact the spines of [blanks]

dendrites

Gray’s type II synapse, AKA the symmetric synapse, generally contact the [blank] body

cell

Gray’s type I synapses are [blank] and mainly permeable to Na+ and K+ (Ach, Glutamate)

excitatory

Gray’s type II synapses are [blank] and are mainly permeable to Cl- (GABA, Glycine)

inhibitory

step 1 of NT life cycle: [blank] transport into the axon

precursor

2: synthesis into neurotransmitter using enzymes/cofactors & 3: storage in [blanks]

vesicles

4: calcium triggered release of vesicles into the synapse & 5: neurotransmitter [blank] of the dendritic receptors

activation

6: termination of neurotransmitters via enzymatic degradation, [blank], auto receptor modulation, and re-uptake

diffusion

current decay is faster because current will directly go through the channels while the charge of the potential is held of by the membrane acting as a [blank]

capacitor

EPSPs and IPSPs are both common, have no refractory period, and can [blank]

summate

[blank] are closer to the threshold and decrease membrane potential while IPSPs hyper polarize,

EPSPs

[blanks] are chemically gated ion channels, fast as speed of light, graded (summation), duration (10-100ms), decrement (weaken over time and space)

post synaptic potentials

temporal summation is repeated stimulations over time while spatial summation is having [blank] synapses

multiple

[blank] sensitive ion channels (AMPA/NMDA receptors are K+-Na+/Ca++ permeable) depolarize postsynaptic membrane and allows excitation and generation of action potentials

glutamate

[blank] sensitive ion channels (GABAA; Cl- permeable ) clamps the membrane potential below the threshold needed for action potential firing

GABA

[blanks] synapses involve indirect gating and 2nd messenger: eg. GPCRs and receptor tyrosine kinases

slow

[blanks] are G protein coupled receptors and are found in the membrane of presynaptic terminals and serve as a feedback loop in signal transduction

autoreceptors