Chapter 8: Synaptic Transmission & Neural Integration Flashcards
For cells that communicate by electrical synapses, the message travels between cells via ________.
gap junctions
Which of the following statements about synapses is FALSE?
Neurotransmitters can move from one cell to another through gap junctions at an electrical synapse.
Which of the following statements about electrical synapses is FALSE?
All electrical synapses provide for bi-directional communication.
The chemical synapse is bounded by the ________ neuron, from which neurotransmitters are released across the synaptic cleft, to the ________ neuron, where the receptors for that neurotransmitter are located.
presynaptic : postsynaptic
What type of synapse occurs between an axon terminal of one neuron and the axon from another neuron?
axoaxonic synapse
What type of synapse occurs between an axon terminal of one neuron and the cell body of another neuron?
axosomatic synapse
The neurotransmitter that is released from the presynaptic neuron must diffuse across the ________ to reach the postsynaptic neuron.
synaptic cleft
What type of ion channels are necessary for the function of the axon and the axon terminal?
voltage-gated
Synaptic vesicles store ________.
neurotransmitter
Most neurotransmitters are synthesized in what region of a neuron?
cytosol
Neurotransmitter release occurs by what mechanism?
exocytosis
Voltage-gated calcium channels in the axon terminal open in response to which of the following?
arrival of an action potential at the axon terminal
The influx of calcium into the axon terminal of a chemical synapse is responsible for which of the following?
fusion of vesicles to the membrane and of exocytosis neurotransmitter
Which of the following is NOT a mechanism whereby neurotransmitters are rapidly removed from the synaptic cleft?
transport back up the axon to be immediately repackaged
Neurotransmitters can be reused through the process of ________, where neurotransmitters are transported across the presynaptic membrane.
reuptake
The extent of neurotransmitter binding to receptors on the postsynaptic membrane is determined primarily by which of the following?
the concentration of neurotransmitter
The synaptic delay is caused by the time required for which step of neurotransmitter release?
calcium entry to trigger exocytosis
What type of receptor is responsible for the rapid opening of ion channels in response to the interaction between the ligand and receptor?
ionotropic receptor
The opening of ion channels that is stimulated by the binding of a neurotransmitter to its receptor on a neighboring neuron, and the subsequent movement of ions across that membrane, describes the development of which of the following?
postsynaptic potential
The rapid change in membrane potential that occurs when a ligand binds to an ionotropic receptor is caused by which of the following?
the presence of one protein that functions as both an ionotropic receptor and an ion
channel
Synaptic potentials are produced at what type of synapse?
axo-dendritic and axo-somatic synapses only
At ionotropic receptors, a(n) ________.
neurotransmitter binding to a receptor opens channels that are a part of the same protein
as the receptor
Presynaptic modulation occurs at what type of synapse?
axo-axonic
Metabotropic receptor-induced gating of ion channels requires more time to occur because of which of the following?
their gating is linked to a G protein
What is a change in the postsynaptic potential that brings membrane potential closer to threshold called?
excitatory postsynaptic potential
The most common mechanism for producing a fast EPSP involves which of the following?
opening of channels that permit both sodium and potassium to flow through
What ion directly triggers neurotransmitter release from the presynaptic neuron?
calcium
An example of a slow excitatory postsynaptic potential that involves closure of potassium channels relies on cAMP produced by what enzyme?
adenylate cyclase
The duration of a slow, excitatory postsynaptic potential mediated by cAMP is driven by the extent of time that cAMP remains active before being degraded by what protein?
phosphodiesterase
Fast excitatory responses not only occur quickly, but ________.
they end quickly
The binding of a neurotransmitter to its receptor at an inhibitory synapse can lead to the ________ of ________ channels.
opening : chloride
The binding of a neurotransmitter to its receptor at an inhibitory synapse can lead to the ________ of ________ channels.
opening : potassium
In the absence of active chloride ion transport, opening of chloride channels in a cell that has hyperpolarized will result in which of the following?
net movement of chloride out of the cell
In the presence of active chloride ion transport within a neuron, the opening of chloride channels will result in which of the following?
net movement of chloride into the cell
If the resting membrane potential is equal to chlorideʹs equilibrium potential, in which direction will chloride ions move if chloride channels open while the cell remains at resting membrane potential?
Ions will move equally in both directions.
In the absence of an active chloride transporter in the plasma membrane, chloride acts to ________ membrane potential by resisting any change in membrane potential.
stabilize
The opening of a chloride channel acts to ________ the development of an action potential at the axon hillock.
inhibit
Convergence in neurophysiology refers to which of the following?
the communication of several neurons to one postsynaptic cell
The final integration of postsynaptic potentials that determines whether an action potential is generated occurs within what region of a neuron?
axon hillock
The degree of summation that can occur for inhibitory postsynaptic potentials is limited by what?
the equilibrium potential for the ion creating the hyperpolarization
For ionotropic receptors, their ________ response ________ the likelihood that two pulses from the same neuron will summate.
rapid : decreases
Which of the following would increase the likelihood of an action potential being generated in a postsynaptic cell?
presynaptic excitation at an excitatory synapse
Which of the following statements about inhibitory synapses is FALSE?
In presynaptic inhibition, opening of chloride channels can stabilize the membrane,
opposing a depolarizing force.
For the slow receptors, the likelihood of summation is ________ by the ________ of time required for those responses to decay.
increased : long period
As the amplitude of the excitatory postsynaptic potential increases above threshold, the time between each action potential will ________, thereby increasing the ________ of the action potentials.
decrease : frequency
Suprathreshold graded potentials within a neuron can generate ________ action potential(s) at the axon hillock, which allows for the ________ of the magnitude of the stimulus.
multiple : frequency coding
Axoaxonic synapses are responsible for ________ the extent of neurotransmitter released at the synapse.
modulating
Presynaptic modulation of neurotransmitter release involves modifying ________ at the axon terminal.
calcium influx
During presynaptic inhibition, the release of a neurotransmitter from the modulating neuron causes which of the following?
a decrease in neurotransmitter release from the neuron it is modulating