Electrical properties of neuronal cells

Question 1

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.”

Answer 1

True

Question 2

True/false
“Action potentials are generated in the dendrites of neurons where they are mediated by
non-gated ion channels”

Answer 2

False

Question 3

True/false

“There is an influx of Ca2+ via voltage-gated channels during action potentials”

Answer 3

True

Question 4

True/false
“The conduction velocity of action potentials is affected by the diameter of the axons and
by their myelination”

Answer 4

True

Question 5

True/false

“Action potentials are only mediated by activation of voltage-gated channels”

Answer 5

True

Question 6

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.

Answer 6

Tyrosine -> DOPA -> Dopamine -> Noradrenaline -> Adrenaline

Tyrosine hydoxylase: rate-limiting enzyme

Question 7

How is glutamate inactivated?

Answer 7

It is (primarily) taken up into adjacent astrocytes in which it is converted to glutamine.

Question 8

How is acetylcholine inactivated?

Answer 8

It is broken down by acetylcholinesterase into choline and acetate, choline is then taken
up in the nerve terminal.

Question 9

True/False

“The ion channels actively transport ions across the plasma membrane”

Answer 9

False

Question 10

True/false
“Ion channels allow ions to pass through in one direction from the outside to the inside of
a neuron”

Answer 10

False

Question 11

True/false
“Ion channels are endowed with a selectivity filter that specifically recognize and select a
given ion type”

Answer 11

True

Question 12

True/false

“The activation and inactivation gates are located in different parts of Na+ channels”

Answer 12

True

Question 13

True/false

“The direction of the flux of ion is only determined by the driving force”

Answer 13

True

Question 14

What characterizes the resting membrane potential?

Answer 14

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

Question 15

True/false
“The passive membrane properties are specific to each neuron and do not involve
activation of ion channels”

Answer 15

True

Question 16

True/false

“The spatial summation is more efficient in neurons with a long space constant”

Answer 16

True

Question 17

True/false

“The temporal summation is also more efficient in neurons with a long space constant”

Answer 17

False

Question 18

True/false

“Neurons with large time and space constants have less efficient summation”

Answer 18

False

Question 19

True/false

“The shape of action potentials is not determined by the time constant of a neuron”

Answer 19

True

Question 20

True/false

“Both gated- and non-gated channels are closed at the resting membrane potential”

Answer 20

False

Question 21

True/false

“Gated channels become open only in response to specific stimuli”

Answer 21

True

Question 22

True/false

“Non-gated ion channels are not present in all neurons”

Answer 22

False

Question 23

True/false

“Ligand-gated channels can be gated by stimuli from the outside or the inside of a neuron”

Answer 23

True

Question 24

True/false

“Both gated and non-gated ion channels become inactivated with a prolonged stimulation”

Answer 24

False

Question 25

True/false "The permeability of Na and K ions through non-gated channels is the same at the resting membrane potential"

Answer 25

False

Question 26

True/false "Ion flux through both gated- and non-gated ion channels determines the resting membrane potential"

Answer 26

False

Question 27

True/false "The resting membrane potential is set by a combined flux of Na and K ions via non-gated channels"

Answer 27

True

Question 28

True/false | "The direction of ion flux through ion channels is affected by the resting membrane potential"

Answer 28

True

Question 29

True/false | "The resting membrane potential contributes to setting the driving force through different ion channels"

Answer 29

True

Question 30

True/false | "Action potentials are triggered by ligand-gated sodium and potassium channels"

Answer 30

False

Question 31

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"

Answer 31

True

Question 32

True/false | "Action potentials unidirectional propagation is controlled by sodium channel inactivation"

Answer 32

True

Question 33

True/false "The frequency of action potential firing does not change, i.e. always constant, for a given neuron"

Answer 33

False

Question 34

True/false | "Action potentials are only mediated by activation of voltage-gated channels"

Answer 34

True

Question 35

True/false | "Synaptic summation is less efficient with higher time and space constants"

Answer 35

False

Question 36

True/false "The time and space constants do not affect the amplitude and conduction velocity of action potentials"

Answer 36

True

Question 37

True/false | "The time and space constants affect the release of transmitters from axon terminals"

Answer 37

False

Question 38

True/false | "The time and space constants can only influence subthreshold postsynaptic potentials"

Answer 38

True

Question 39

True/false | "The resting membrane potential of a neuron determines its time and space constants"

Answer 39

False

Question 40

What is the role of afterhyperpolarization in the action potential?

Answer 40

The early afterhyperpolarization regulates the frequency of action potentials

Question 41

What is synaptic summation dependent on?

Answer 41

A) Synaptic summation depends on the time constant | B) Synaptic summation depends on the space constant

Question 42

What is the relative refractory period dependent on?

Answer 42

The relative refractory period depends on K+ channels

Question 43

What is true about cell excitability?

Answer 43

Excitability depends on voltage-gated ion channels

Question 44

True/false | "The amplitude of action potentials is determined by the neuron’s time and space constants"

Answer 44

False

Question 45

True/false | "Synaptic summation is more efficient with higher time and space constants"

Answer 45

True

Question 46

True/false "The time and space constants affect the action potential propagation and release of transmitters from axon terminals"

Answer 46

False

Question 47

True/false | "The time and space constants only influence sub-threshold postsynaptic potentials"

Answer 47

True

Question 48

True/false | "The time and space constants are larger at more hyperpolarized membrane potentials"

Answer 48

False

Question 49

True/false "The electrical signal of an AP is converted to a chemical signal at synapses with only electrical transmission via gap junctions"

Answer 49

False

Question 50

True/false | "During an action potential, all voltage-gated channels can be activated"

Answer 50

True

Question 51

True/false | "Action potentials unidirectional propagation is controlled by sodium channel inactivation"

Answer 51

True

Question 52

True/false | "The afterhyperpolarization is mediated by both voltage- and ligand-gated K+ channels"

Answer 52

True

Question 53

True/false | "The frequency of action potential firing is always constant for each neuron"

Answer 53

False

Question 54

True/false | "The driving force of ions helps to set the RMP"

Answer 54

True

Question 55

True/false | "The difference in permeability of ions is important in setting the RMP"

Answer 55

True

Question 56

True/false | "The permeability of Na vs K does not play an important role in setting the RMP"

Answer 56

False

Question 57

True/false | "The RMP does not influence the direction of ion flux through ion channels"

Answer 57

False

Question 58

True/false | "The RMP is the same for all neurons in the brain"

Answer 58

False

Question 59

True/false | "Na+ channel inactivation determines the shape, but not the propagation of action potentials"

Answer 59

False

Question 60

True/false | "The fast activation of Na+ channels and their inactivation are essential for the generation of action potentials"

Answer 60

True

Question 61

True/false | "All ion channels undergo inactivation"

Answer 61

False

Question 62

True/false | "All voltage-gated channels present in a neuron can be activated by an action potential"

Answer 62

True

Question 63

True/false | "Both voltage- and ligand-gated K+ channels underlie the afterhyperpolarizations"

Answer 63

True

Question 64

True/False | "Neurons’ time and space constants are determined by voltage-gated ion channels"

Answer 64

False

Question 65

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"

Answer 65

True

Question 66

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"

Answer 66

False

Question 67

True/False | "Small EPSPs can summate more efficiently if they occur in neurons with long space and time constants"

Answer 67

True

Question 68

True/False | "The time and space constants determine the shape and the propagation of action potentials"

Answer 68

False

Question 69

True/False | "The structure of ion channels determines the direction of the flow of ions"

Answer 69

False

Question 70

True/False " The opening and inactivation of an ion channel are mediated by conformational changes occurring at different parts of a channel"

Answer 70

True

Question 71

True/False "The direction of the flow of ions is determined by the driving force, which is independent of the channel itself"

Answer 71

True

Question 72

True/False | "All gated channels contribute to the generation of action potentials"

Answer 72

False

Question 73

True/False | "The resting membrane potential is determined by both gated and non-gated ion channels"

Answer 73

False

Question 74

True/False | "The firing frequency of action potentials does not vary among neurons"

Answer 74

False

Question 75

True/False | "The amplitude of the slow afterhyperpolarization can affect the firing frequency of action potentials"

Answer 75

True

Question 76

True/False | "The firing frequency of neurons increases with the strength of excitatory synaptic inputs

Answer 76

True

Question 77

True/False | "Leak channels have a strong and direct influence on the firing frequency of neurons"

Answer 77

False

Question 78

True/False | "Ca2+ influx can indirectly affect the firing frequency of neurons"

Answer 78

True

Question 79

True/False | "The flow of ions through ion channels requires energy in form of ATP"

Answer 79

False

Question 80

True/False | "Ion channels allow all ions to pass through"

Answer 80

False

Question 81

True/False | "Ion channels have a selectivity filter to specifically recognize and select a given ion type"

Answer 81

True

Question 82

True/False | "Ion channels are membrane lipids that allow ion to pass only in one direction"

Answer 82

False

Question 83

True/False | "The direction of the flux of ion is only determined by the driving force"

Answer 83

True

Question 84

The resting membrane potential of neurons is around -65 mV and is determined by:

Answer 84

1: Passive flow of ions 3: Leak K+ and Na+ channels 5: Non-gated ion channels

Question 85

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

Answer 85

2: The spatial summation increases with an increased space constant 4: Neurons with small time and space constants have a less efficient summation

Question 86

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

Answer 86

2: They can be ionotropic receptors 3: They require specific stimuli to be activated

Question 87

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

Answer 87

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

Question 88

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

Answer 88

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