Electrical properties of neuronal cells Flashcards
True/false
“At presynaptic terminals action potentials can be converted into chemical signals at chemical synapses and also propagated directly as an electrical signal at electricalsynapses.”
True
True/false
“Action potentials are generated in the dendrites of neurons where they are mediated by
non-gated ion channels”
False
True/false
“There is an influx of Ca2+ via voltage-gated channels during action potentials”
True
True/false
“The conduction velocity of action potentials is affected by the diameter of the axons and
by their myelination”
True
True/false
“Action potentials are only mediated by activation of voltage-gated channels”
True
Catecholamines are important neurotransmitters linked with many different functions. How are they synthesized? Start with the precursor and end with the final product (each compound in the correct order). State also the name and role of the rate-limiting enzyme.
Tyrosine -> DOPA -> Dopamine -> Noradrenaline -> Adrenaline
Tyrosine hydoxylase: rate-limiting enzyme
How is glutamate inactivated?
It is (primarily) taken up into adjacent astrocytes in which it is converted to glutamine.
How is acetylcholine inactivated?
It is broken down by acetylcholinesterase into choline and acetate, choline is then taken
up in the nerve terminal.
True/False
“The ion channels actively transport ions across the plasma membrane”
False
True/false
“Ion channels allow ions to pass through in one direction from the outside to the inside of
a neuron”
False
True/false
“Ion channels are endowed with a selectivity filter that specifically recognize and select a
given ion type”
True
True/false
“The activation and inactivation gates are located in different parts of Na+ channels”
True
True/false
“The direction of the flux of ion is only determined by the driving force”
True
What characterizes the resting membrane potential?
The resting membrane potential is determined by K+ and Na+ ion flow through leak channels
Na/K-ATPase plays a supporting role and hence its activation is required for maintaining the resting membrane potential
True/false
“The passive membrane properties are specific to each neuron and do not involve
activation of ion channels”
True
True/false
“The spatial summation is more efficient in neurons with a long space constant”
True
True/false
“The temporal summation is also more efficient in neurons with a long space constant”
False
True/false
“Neurons with large time and space constants have less efficient summation”
False
True/false
“The shape of action potentials is not determined by the time constant of a neuron”
True
True/false
“Both gated- and non-gated channels are closed at the resting membrane potential”
False
True/false
“Gated channels become open only in response to specific stimuli”
True
True/false
“Non-gated ion channels are not present in all neurons”
False
True/false
“Ligand-gated channels can be gated by stimuli from the outside or the inside of a neuron”
True
True/false
“Both gated and non-gated ion channels become inactivated with a prolonged stimulation”
False
True/false
“The permeability of Na and K ions through non-gated channels is the same at the resting
membrane potential”
False
True/false
“Ion flux through both gated- and non-gated ion channels determines the resting membrane
potential”
False
True/false
“The resting membrane potential is set by a combined flux of Na and K ions via non-gated
channels”
True
True/false
“The direction of ion flux through ion channels is affected by the resting membrane potential”
True
True/false
“The resting membrane potential contributes to setting the driving force through different ion channels”
True
True/false
“Action potentials are triggered by ligand-gated sodium and potassium channels”
False
True/false
“The electrical signal of an action potential is converted to a chemical signal at axon
terminals via activation of voltage-gated calcium channels”
True
True/false
“Action potentials unidirectional propagation is controlled by sodium channel inactivation”
True
True/false
“The frequency of action potential firing does not change, i.e. always constant, for a given
neuron”
False
True/false
“Action potentials are only mediated by activation of voltage-gated channels”
True
True/false
“Synaptic summation is less efficient with higher time and space constants”
False
True/false
“The time and space constants do not affect the amplitude and conduction velocity of action
potentials”
True
True/false
“The time and space constants affect the release of transmitters from axon terminals”
False
True/false
“The time and space constants can only influence subthreshold postsynaptic potentials”
True
True/false
“The resting membrane potential of a neuron determines its time and space constants”
False
What is the role of afterhyperpolarization in the action potential?
The early afterhyperpolarization regulates the frequency of action potentials
What is synaptic summation dependent on?
A) Synaptic summation depends on the time constant
B) Synaptic summation depends on the space constant
What is the relative refractory period dependent on?
The relative refractory period depends on K+ channels
What is true about cell excitability?
Excitability depends on voltage-gated ion channels
True/false
“The amplitude of action potentials is determined by the neuron’s time and space constants”
False
True/false
“Synaptic summation is more efficient with higher time and space constants”
True
True/false
“The time and space constants affect the action potential propagation and release of
transmitters from axon terminals”
False
True/false
“The time and space constants only influence sub-threshold postsynaptic potentials”
True
True/false
“The time and space constants are larger at more hyperpolarized membrane potentials”
False
True/false
“The electrical signal of an AP is converted to a chemical signal at synapses with only
electrical transmission via gap junctions”
False
True/false
“During an action potential, all voltage-gated channels can be activated”
True
True/false
“Action potentials unidirectional propagation is controlled by sodium channel inactivation”
True
True/false
“The afterhyperpolarization is mediated by both voltage- and ligand-gated K+ channels”
True
True/false
“The frequency of action potential firing is always constant for each neuron”
False
True/false
“The driving force of ions helps to set the RMP”
True
True/false
“The difference in permeability of ions is important in setting the RMP”
True
True/false
“The permeability of Na vs K does not play an important role in setting the RMP”
False
True/false
“The RMP does not influence the direction of ion flux through ion channels”
False
True/false
“The RMP is the same for all neurons in the brain”
False
True/false
“Na+ channel inactivation determines the shape, but not the propagation of action potentials”
False
True/false
“The fast activation of Na+ channels and their inactivation are essential for the generation of action potentials”
True
True/false
“All ion channels undergo inactivation”
False
True/false
“All voltage-gated channels present in a neuron can be activated by an action potential”
True
True/false
“Both voltage- and ligand-gated K+ channels underlie the afterhyperpolarizations”
True
True/False
“Neurons’ time and space constants are determined by voltage-gated ion channels”
False
True/False
“The time and space constants play a key role only at subthreshold membrane potentials,
that is when neurons are not firing action potentials”
True
True/False
“EPSPs with large amplitudes will always summate efficiently to produce an action
potential regardless of how short the time and space constants are”
False
True/False
“Small EPSPs can summate more efficiently if they occur in neurons with long space and time constants”
True
True/False
“The time and space constants determine the shape and the propagation of action potentials”
False
True/False
“The structure of ion channels determines the direction of the flow of ions”
False
True/False
“ The opening and inactivation of an ion channel are mediated by conformational changes
occurring at different parts of a channel”
True
True/False
“The direction of the flow of ions is determined by the driving force, which is independent
of the channel itself”
True
True/False
“All gated channels contribute to the generation of action potentials”
False
True/False
“The resting membrane potential is determined by both gated and non-gated ion channels”
False
True/False
“The firing frequency of action potentials does not vary among neurons”
False
True/False
“The amplitude of the slow afterhyperpolarization can affect the firing frequency of action potentials”
True
True/False
“The firing frequency of neurons increases with the strength of excitatory synaptic inputs
True
True/False
“Leak channels have a strong and direct influence on the firing frequency of neurons”
False
True/False
“Ca2+ influx can indirectly affect the firing frequency of neurons”
True
True/False
“The flow of ions through ion channels requires energy in form of ATP”
False
True/False
“Ion channels allow all ions to pass through”
False
True/False
“Ion channels have a selectivity filter to specifically recognize and select a given ion type”
True
True/False
“Ion channels are membrane lipids that allow ion to pass only in one direction”
False
True/False
“The direction of the flux of ion is only determined by the driving force”
True
The resting membrane potential of neurons is around -65 mV and is determined by:
1: Passive flow of ions
3: Leak K+ and Na+ channels
5: Non-gated ion channels
The passive membrane properties of neurons determine the efficacy of summation of synaptic inputs. Which of the following statement(s) is (are) correct:
1: The time and space constants do not vary between different types of neurons
2: The spatial summation increases with an increased space constant
3: The temporal summation decreases with increased space constant
4: Neurons with small time and space constants have a less efficient summation
5: The shape of action potentials is determined by the time constant of the neuron
2: The spatial summation increases with an increased space constant
4: Neurons with small time and space constants have a less efficient summation
Ion channels comprise two different types: gated- and non-gated channels. Gated
ion channels display the following properties: (2 p)
1: They can only be activated by stimuli acting from the outside of neurons
2: They can be ionotropic receptors
3: They require specific stimuli to be activated
4: They contribute to setting the resting membrane potential of neurons
5: All gated ion channels become inactivated with a prolonged stimulation
2: They can be ionotropic receptors
3: They require specific stimuli to be activated
An Action potential (AP) transmits the electrical signals along the axons of
neurons. Which of the following statement(s) is(are) correct: (2 p)
1: The electrical signal of an AP is converted to a chemical signal at axon
terminals
2: Action potentials are triggered by ligand-gated sodium channels
3: Action potentials unidirectional propagation is controlled by sodium channel
inactivation
4: Action potentials are mediated by voltage-gated channels
5: The amplitude of action potentials does not change with the stimulus strength
1: The electrical signal of an AP is converted to a chemical signal at axon
terminals
3: Action potentials unidirectional propagation is controlled by sodium channel
inactivation
4: Action potentials are mediated by voltage-gated channels
All neurons have a resting membrane potential (RMP) around -65 mV. Which of
the following statement(s) is(are) correct: (2 p)
1: Only ion flux through gated-ion channels determines the RMP
2: The RMP is set by a combined flux of Na and K ions
3: The permeability of Na vs K does not play an important role in setting the RMP
4: The RMP influences the direction of ion flux through ion channels
5: The RMP can vary between neurons in different regions of the brain
2: The RMP is set by a combined flux of Na and K ions
4: The RMP influences the direction of ion flux through ion channels
5: The RMP can vary between neurons in different regions of the brain