CHAPTERS 1-34 EXAMINATION TEST 2026
COMPLETE QUESTIONS AND SOLUTIONS
GRADED A+
⩥ Synapses. Answer: location where 2 neurons interact and exchange
either chemical or electrical signals
more synapses means more learning and communication
∙losing synapses = neurodegenerative disorders
Synapses require 2 neurons: presynaptic neuron that sends signal and
postsynaptic neuron that receives signal
2 classes of synapses based on type of signal used: electrical or chemical
∙electrical synapses function through electrical signals
∙chemical synapses function through neurotransmitters
3 types of synapses named for where the synapse occurs on the
postsynaptic cell
∙each synapse is formed by axon of presynaptic neuron and either the
cell body (axosomatic), dendrite (axodendritic) or axon (axoaxonic) of
the postsynaptic neuron
,⩥ Electrical Synapses. Answer: the minority class of synapses
rely on gap junctions to transmit electrical signals
important features are that communication b/w neurons is passive and
faster than chemical synapses, they are always excitatory and the signal
is bidirectional
∙postsynaptic neuron can send signals back to the presynaptic neuron
∙however, the original presynaptic signal is always larger than the
response by the postsynaptic neuron
most involved in synchronizing activity of a given population of neurons
∙are involved in extreme neuronal activity of epilepsy
the gap junctions are the same as gap junctions found in other tissues
(i.e. cardiac muscles)
∙composed on connexin (protein subunits) that interact to form connexon
pores in the cell membrane
∙these connexons then pair pair with connexons on postsynaptic
membrane to form a continuous tube from the presynaptic neuron to the
postsynaptic neuron
∙ions and various other macromolecules (including ATP) can then pass
across the synapse from presynaptic to postsynaptic
,⩥ Chemical Synapses. Answer: large majority class of synapses
rely on the release of chemical neurotransmitters from the presynaptic
neuron and their interaction with receptors on the postsynaptic neuron
∙makes the process slower, but more dynamic, allowing for greater
control of the strength of the signal, as well as whether the effect will be
excitatory/inhibitory
chemical synapses are unidirectional
due to the lack of anchoring by gap junctions involved in electrical
synapses, chemical synapses have 2 different junctions b/w pre and
postsynaptic neurons
∙synaptic junctions are the actual site of signal transmission and include
the active zone of the presynaptic neuron as well as the postsynaptic
density of the postsynaptic cell
∙puncta adherentia are the mechanical adhesion sites outside of the
synaptic junctions that hold the pre and postsynaptic cell sin class
chemical synapses exist as three distinct segments: presynaptic, synaptic
cleft and postsynaptic
∙each of these regions has characteristic components that distinguish if
from the others
, ⩥ Presynaptic Components. Answer: distinguished most noticeably by
the presence of vesicles containing neurotransmitters
∙vesicles are small (30-35nm) and store nonpeptide neurotransmitters
∙packaging NTs into vesicles allows for faster and more precise control
over their release by regulating the amount and timing of NT release
∙NTs are recycled by a variety of mechanisms and are involved in re-
uptake of NTs
synaptic vesicles exist in 3 pools based on their location and ability to be
released
∙readily available pool is docked to the presynaptic membrane and is
released as soon as there is a signal to do so
→this pool is small and quickly exhausted
∙recycling pool is close to the presnaptic membrane, but not docked and
ready for release
→these vesicles are larger than the readily releasable pool, but require a
larger or longer signal to be released into the synapse
∙third pool is the reserved pool, whose vesicles are the furthest from the
membrane and consist of most of the vesicles in the neuron
→requires the largest stimulation to be released and may only be
released after all other pools are exhausted
presynaptic vesicles are released by exocytosis involving SNARES and
Ca2+