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Bio > 12.4 > Flashcards

12.4 Flashcards

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Biology 101 flashcards
1
Q

What is the resting membrane potential of a typical neuron?

A

-70 mV

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2
Q

True or False: The resting membrane potential is primarily determined by the concentration of sodium ions inside the cell.

A

False

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3
Q

Fill in the blank: The primary ions involved in generating the action potential are _____ and _____.

A

sodium, potassium

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4
Q

What is the threshold potential required to trigger an action potential?

A

-55 mV

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5
Q

Which ion channels open first during the depolarization phase of an action potential?

A

Sodium channels

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6
Q

What is the term for the period during which a neuron cannot fire another action potential?

A

Refractory period

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7
Q

True or False: During the repolarization phase, potassium channels open and sodium channels close.

A

True

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8
Q

What is the role of myelin in neuronal conduction?

A

To increase the speed of action potential propagation

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9
Q

Define depolarization.

A

A decrease in the membrane potential, making the inside of the cell more positive.

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10
Q

What is the function of the sodium-potassium pump?

A

To maintain the resting membrane potential by pumping sodium out and potassium in.

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11
Q

Fill in the blank: The all-or-nothing principle states that an action potential either occurs or _____ when the threshold is reached.

A

does not occur

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12
Q

What is the typical duration of an action potential?

A

1-2 milliseconds

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13
Q

Which phase of the action potential is characterized by a rapid influx of sodium ions?

A

Depolarization phase

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14
Q

What is hyperpolarization?

A

An increase in the membrane potential, making the inside of the cell more negative.

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15
Q

True or False: Action potentials can vary in amplitude.

A

False

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16
Q

What type of synapse involves the direct transfer of ions between cells?

A

Electrical synapse

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17
Q

What is the main neurotransmitter released at the neuromuscular junction?

A

Acetylcholine

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18
Q

Fill in the blank: An excitatory postsynaptic potential (EPSP) _____ the likelihood of an action potential.

A

increases

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19
Q

What is the role of calcium ions in neurotransmitter release?

A

They trigger the fusion of neurotransmitter vesicles with the presynaptic membrane.

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20
Q

Define graded potential.

A

A change in membrane potential that varies in size and can summate.

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21
Q

True or False: Graded potentials can lead to action potentials if they reach the threshold.

A

True

22
Q

What is the term for the time between the arrival of an action potential at the axon terminal and the release of neurotransmitters?

A

Synaptic delay

23
Q

What type of ion channel opens in response to a change in membrane potential?

A

Voltage-gated ion channel

24
Q

What is the role of inhibitory neurotransmitters?

A

To decrease the likelihood of an action potential in the postsynaptic neuron.

25
Q

Fill in the blank: The process of converting an electrical signal into a chemical signal is called _____ transmission.

A

chemical

26
Q

What is the function of the axon hillock?

A

To integrate incoming signals and determine whether to fire an action potential.

27
Q

True or False: All neurons release the same type of neurotransmitter.

A

False

28
Q

What is the effect of myelin on capacitance in neurons?

A

It decreases capacitance, allowing for faster signal transmission.

29
Q

What is the primary effect of local anesthetics on neurons?

A

They block sodium channels to prevent action potentials.

30
Q

What occurs during the after-hyperpolarization phase?

A

The membrane potential becomes more negative than the resting potential.

31
Q

Fill in the blank: The _____ potential is the change in membrane potential caused by synaptic activity.

A

postsynaptic

32
Q

What is the significance of the nodes of Ranvier?

A

They allow for saltatory conduction, increasing the speed of action potentials.

33
Q

Which structure in the neuron receives incoming signals?

A

Dendrites

34
Q

True or False: Neurotransmitters can be either excitatory or inhibitory.

A

True

35
Q

What is the typical threshold for excitatory postsynaptic potentials (EPSPs)?

A

-55 mV

36
Q

Fill in the blank: The _____ phase of the action potential is characterized by the efflux of potassium ions.

A

repolarization

37
Q

What happens to the membrane potential during an action potential?

A

It rapidly depolarizes and then repolarizes.

38
Q

True or False: The frequency of action potentials can encode information about stimulus intensity.

A

True

39
Q

What is the primary role of astrocytes in the nervous system?

A

To support neurons and maintain the blood-brain barrier.

40
Q

Fill in the blank: The _____ is the site of action potential initiation.

A

axon hillock

41
Q

What is the consequence of a failure in the sodium-potassium pump?

A

Disruption of the resting membrane potential and potential cell death.

42
Q

What is the primary effect of potassium channel blockers on neurons?

A

Prolonged action potentials.

43
Q

Fill in the blank: The action potential travels along the axon through _____ conduction.

A

saltatory

44
Q

Which type of receptor responds to neurotransmitters and opens ion channels?

A

Ionotropic receptors

45
Q

What is the role of metabotropic receptors?

A

To activate intracellular signaling pathways that can affect ion channel activity.

46
Q

True or False: Action potentials are graded responses.

A

False

47
Q

What is the effect of the depolarization of the postsynaptic membrane?

A

It can lead to an excitatory postsynaptic potential (EPSP).

48
Q

Fill in the blank: The _____ is the gap between two neurons at a synapse.

A

synaptic cleft

49
Q

What is the significance of the absolute refractory period?

A

It ensures that action potentials are unidirectional and prevents overlapping.

50
Q

What is the role of neurotransmitter reuptake?

A

To terminate the action of neurotransmitters in the synaptic cleft.

51
Q

True or False: Neurons can regenerate action potentials indefinitely.

A

True

52
Q

What determines the speed of action potential conduction?

A

Axon diameter and myelination

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