Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

BSCI 1511 > Neurons, Synapses, & Signaling > Flashcards

Neurons, Synapses, & Signaling Flashcards

1
Q

What are the four stages of information processing?

A
  1. Sensory input
  2. Integration
  3. Motor output
  4. Learning and memory
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the role of the sensory input stage of information processing?

A

It receives information–sensing the external environment (e.g. light) or internal conditions (e.g. blood pressure).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the role of the integration stage of information processing?

A

It processes information–processing sensory input in context.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is the role of the motor output stage of information processing?

A

It transmits information directing a physiological or behavioral response (e.g. activation of muscle, gland, etc).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the role of the learning and memory stage of information processing?

A

It provides a mechanism for using experience to modify the response.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

How does a cone snail illustrate the stages of information processing?

A

The snail has a siphon that senses changes in the current and the water, such that if a fish came near, it could sense that. The siphon then takes that information it sensed and passes it off to be integrated. This leads to a motor output–the projection of a proboscis that will skew the fish so it can be eaten.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

How are the stages of information processing enacted?

A

These processes involve changes in the electrical potential (voltage) across the plasma membrane that arise from the regulated movement of ions across the membrane.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the basic unit of the nervous system?

A

The neuron.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What do neurons use electrical current for?

A

They use pulses of electrical current to receive, transmit, and regulate the flow of information over long distances.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the purpose of groups of neurons organized into a brain or ganglia?

A

A brain or ganglia carry out the interpretation of nerve impulses involved in sorting paths and connections.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Which two parts of the neuron receive signals from other neurons?

A

The cell body and branched extensions called dendrites receive signals from other neurons.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

After reception by the cell body and dendrites, where does the neuronal signal travel?

A

The signal travels to the axon hillock, and then via the neuron’s single, long axon.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Which part of the neuron transmits the information to another cell? How?

A

Each branched end of an axon contains synaptic terminals that transmit information to another cell (or multiple cells) at junctions called synapses.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

How do neurotransmitters work?

A

Chemical messengers called neurotransmitters pass information from the transmitting neuron–called the presynaptic cell–to the receiving cell–called the postsynaptic cell.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What do sensory neurons do?

A

They transmit information about external and internal stimuli. (sense -> transmit)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What do interneurons do?

A

They integrate the information; most neurons in the brain are interneurons, forming circuits within the brain. (encode the meaning of the collective signals)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What do motor neurons do?

A

They extend out of the processing centers and trigger a response: muscle or gland activity.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What are the three broad classes of neurons?

A
  1. Sensory neurons
  2. Interneurons
  3. Motor neurons
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Which types of neurons are part of the peripheral nervous system?

A

Sensory neurons and motor neurons.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Which types of neurons are part of the central nervous system?

A

Interneurons.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What are nerves?

A

Bundles of neuron axons.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What are the functions of glial cells (glia)?

A

These are the neuron’s supporting cells.
1. Nourish neurons
2. Insulate axons
3. Immune protection
4. Regulate the extracellular fluid surrounding neurons.
5. Sometimes replenish neurons and transmit information.
6. Facilitate nervous system development.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What do ependymal cells do?

A

They line the ventricles of the brain.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What do astrocytes do?

A

They facilitate information transfer, participate in the formation of the blood-brain barrier, neuronal stem cells.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What do oligodendrocytes do?

A

They myelinate axons in the CNS.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What are microglia?

A

They are immune cells in the CNS.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What do Schwann cells do?

A

They myelinate axons in the PNS.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What is the difference between oligodendrocytes and Schwann cells?

A

They have the same function–myelination of axons–but oligodendrocytes are in the CNS while Schwann cells are in the PNS.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

When the neuron is at its resting potential, how are ions distributed?

A

Ions are unequally distributed between the interior of cells and the surrounding fluid.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

At resting potential, what is the charge of the inside of a cell relative to the outside of the cell?

A

It is negatively charged.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

At resting potential, what is the source of potential energy?

A

The attraction of opposite charges across the plasma membrane is a source of potential energy.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

What is the membrane potential?

A

Membrane potential is the charge difference, or voltage.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

For a resting neuron, what is the resting potential?

A

The resting potential is between -60 and -80 mV.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

What causes changes in the neuron’s membrane potential?

A

Input from other neurons or a specific stimulus causes changes in the neuron’s membrane potential, and this acts as a signal that transmit information.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

At resting potential, what are the intracellular and extracellular concentrations of potassium (K+)?

A

Intracellular: 140 mM
Extracellular: 5 mM

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

At resting potential, what are the intracellular and extracellular concentrations of sodium (Na+)?

A

Intracellular: 15 mM
Extracellular 150 mM

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

At resting potential, what are the intracellular and extracellular concentrations of chloride (Cl-)?

A

Intracellular: 10 mM
Extracellular 120 mM

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

At resting potential, what are the intracellular and extracellular concentrations of large anions (A-) such as proteins?

A

Intracellular: 100 mM
Extracellular: N/A

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

Describe the relative concentrations of calcium (Ca++) inside and outside the neuron.

A

The intracellular concentration is much lower than the extracellular concentration.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

What are the two important characteristics of ion channels?

A
  1. They are selective for specific ions (selective permeability)
  2. They ions across their concentration gradient (do not require energy).
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

What are the characteristics of a leak channel?

A
  1. It is always open.
  2. It is very slow at transporting ions since they can only leak through it.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

What are the characteristics of a ligand-gated channel?

A
  1. It requires a signal.
  2. If it is closed, it cannot do anything.
    An example is the IP3 channel that allows calcium ions out of the ER.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

What activates a voltage-gated channel?

A

It requires a change in membrane potential to activate. Normally the inside of the cell is negatively charged, but if it flips to become positive, this is when the channel activates. (some operate the opposite of that)

44
Q

What activates a mechanically-gated channel?

A

It requires a physical stimulus such as pressure.

45
Q

What maintains the gradients of K+ and Na+ ions across the plasma membrane?

A

ATP-dependent sodium-potassium pumps maintain the gradient.

46
Q

What is the ratio with which sodium-potassium pumps move sodium and potassium ions?

A

They pump 3 Na+ out of the cell for every 2 K+ pumped into the cell.

47
Q

How does the number of K+ leak channels compare to the number of Na+ leak channels in a resting cell?

A

In a resting cell, K+ leak channels allow some K+ to reexit the cell, but there are very few Na+ leak channels.

48
Q

In a resting cell, what causes K+ to flow out through leak channels, and what causes it to stop?

A

K+ flows out because of the chemical gradient and this stops because of the electrochemical gradient.

49
Q

Why do ion pumps require energy?

A

They are moving ions opposite of their concentration of voltage gradient.

50
Q

What two things cause the resting potential–the unequal distribution of charge–of the neuron?

A
  1. ATP-dependent sodium-potassium ion pumps create concentration gradients across the plasma membrane: more K+ inside, more Na+ outside.
  2. The plasma membrane, because it has more leak channels for K+ than for Na+, is more permeable to K+ than Na+.
51
Q

What is the equilibrium potential?

A

E is the magnitude of a cell’s membrane voltage at equilibrium and is calculated using the Nernst equation.
In other words, E is the membrane potential where the electrical gradient is “strong enough” to attract the ions back across the membrane, thereby stopping the net flow of ions driven by the chemical gradient.

52
Q

What is the Nernst equation?

A

Eion = 62 mV(log([ion]outside/[ion]inside)

53
Q

If you put 140 mM of KCl inside a cell and 5 mM on the outside, at what voltage will it reach equilibrium?

A

The K+ ions will dissociate from the Cl- ions and move out of the cell until the electrical gradient stops them. This will be at about -90 mV.

54
Q

If you put 150 mM of NaCl outside a cell and 15 mM on the inside, at what voltage will it reach equilibrium?

A

Sodium will move into the cell because of the chemical gradient, making the inside more positive until the electrical gradient stops it at about +62 mV.

55
Q

How are the voltage potential of potassium and sodium balanced?

A

Potassium potential is about -90 mV and sodium potential is about 62 mV. Since potassium contributes more, the resting potential lies at about -70 mV. Only the small flow of sodium prevents it from reaching the full -90 mV of the potassium potential .

56
Q

What happens when K+ channels are opened?

A

This increases the magnitude of the membrane potential. It becomes more negative, moving toward -90 mV. This is hyperpolarization.

57
Q

What happens when Na+ channels are opened?

A

This decreases the magnitude of the membrane potential. It becomes more positive, moving toward +62 mV. This is depolarization.

58
Q

What is the lowest possible voltage of the neuron, and when does this hyperpolarization occur?

A

-90 mV when potassium rushes out of the cell in response to potassium-gated ion channels opening.

59
Q

How does depolarization occur?

A

Sodium rushes into the cell in response to sodium-gated ion channels opening.

60
Q

What is the threshold equal to?

A

-55 mV.

61
Q

What happens when the threshold is reached?

A

When the threshold voltage is reached, this induces an action potential, which in turn induces rapid depolarization, then hyperpolarization.

62
Q

What are graded potentials?

A

Graded potentials are small changes in membrane potential that either depolarize or hyperpolarize, but do not reach the threshold.

63
Q

If a graded potential occurs alone, what happens?

A

It propagates for a few millimeters before dying out.

64
Q

What are action potentials?

A

Action potentials are a rapid depolarization followed by repolarization that is propagated with fidelity along the axon of a nerve cell, resulting in long-distance signaling.

65
Q

What does it mean to say that action potentials are all-or-nothing responses?

A

They are all the same–digital signals. They have a constant magnitude and either happen or don’t happen.

66
Q

What is the maximum voltage reached during neuronal signaling?

A

+35 mV.

67
Q

Why is the maximum voltage capped at +35 mV?

A
  1. The inactivation loop on voltage-gated sodium ion channels is pushed into the channel because of the change in current, inactivating it and halting the influx of sodium ions.
  2. Potassium channels open, causing K+ ions to leave the cell and making the interior more negative.
68
Q

What happens when the threshold of -55 mV is reached?

A

That opens voltage-gated sodium channels that allow sodium to rush into the cell, causing a massive spike in the potential.

69
Q

How is an action potential conducted down an axon?

A

Sodium influx during the rising phase depolarizes the neighboring region of the axon membrane, reaching the threshold: action potential. This process is repeated along the length of the axon, which results in the movement of the impulse from the cell body to the synaptic terminus.

70
Q

What is the refractory period, and what is its purpose?

A

The refractory period is the brief inactivation of sodium channels that prevent the backflow of information. So even though the influx of sodium ions diffuse laterally in both directions, the signal propagates in a single direction.

71
Q

What conveys the strength of the signal?

A

The frequency of firing.

72
Q

For animals, what are the two types of action potential conduction?

A
  1. Saltatory conduction
  2. Continuous conduction
73
Q

Which type of conduction occurs in vertebrate animals?

A

Saltatory conduction

74
Q

Which type of conduction occurs in invertebrate animals?

A

Continuous conduction

75
Q

How are axons insulated in saltatory conduction?

A

Schwann cells in the PNS and oligodendrocytes in the CNS insulate the axons using myelin.

76
Q

How are axons insulated in continuous conduction?

A

They are not insulated.

77
Q

Where are voltage-gated ion channels found in saltatory conduction?

A

They found only in the gaps between the myelin sheaths, called nodes of Ranvier.

78
Q

Where are voltage-gated ion channels found in continuous conduction?

A

They are found throughout the axon.

79
Q

What is the transfer speed of saltatory conduction?

A

100 m/sec or faster.

80
Q

What is the transfer speed of continuous conduction?

A

5 cm to 30 m/sec.

81
Q

How is the speed of conduction increased with continuous conduction?

A

Axons are made thicker.

82
Q

Is saltatory or continuous conduction evolutionarily older?

A

Continuous conduction is the ancestral state (older).

83
Q

How do myelin sheathes increase conduction speed?

A

They insulate the axon so that the voltage gradient is more fully conserved. Where there is a myelin sheath, there is no loss of ions. There are fewer instances where voltage-gated ion channels need to be opened, so ions diffuse over longer distances.

84
Q

What happens at chemical synapses?

A

Chemical neurotransmitters released by the presynaptic neuron are received by the postsynaptic cell. They are the most common.

85
Q

What happens at electrical synapses?

A

Electric currents flow from one neuron to another via special gap junctions. These mediate rapid, unvarying behaviors like heart contraction. They are the least common.

86
Q

What happens when an action potential arrives at the synapse of the presynaptic neuron?

A

The change in voltage by the action potential triggers the opening of calcium channels, and calcium rushes in, making the inside of the cell much more positive. This also induces neurotransmitter vesicles to fuse with the membrane at the synaptic terminal.

87
Q

What happens when the neurotransmitter vesicles fuse with the membrane at the synaptic terminal?

A

Those neurotransmitters are released into the synaptic cleft, where they bind a receptor, causing it to open.

88
Q

How long is the synaptic cleft?

A

About 50 nm.

89
Q

If the receptor at the synaptic terminal is an ion channel, what is it called?

A

This is called an ionotropic receptor.

90
Q

What triggers an excitatory response at the synapse?

A

When the channel is permeable to both potassium and sodium, it depolarizes. This is called an excitatory postsynaptic potential (EPSP).

91
Q

What triggers an inhibitory response at the synapse?

A

When the channel is permeable to only potassium or only chlorine, it hyperpolarizes. This is called an inhibitory postsynaptic potential (IPSP).

92
Q

What is a receptor that is a GPCR called at a chemical synapse?

A

This is a metabotropic receptor.

93
Q

How do metabotropic receptors work?

A

They activate a signal transduction cascade using a GPCR and a G-protein that involves a second messenger, resulting in the opening or closing of an ion channel. They are slower but have a longer response than ionotropic receptors.

94
Q

What is temporal summation?

A

This occurs when two rapid EPSPs at the same synapse add up to trigger an action potential.

95
Q

What happens when the graded potential is subthreshold with no summation?

A

Since it is not enough to reach threshold, nothing happens.

96
Q

What is spatial summation?

A

This occurs when two simultaneous EPSPs at different synapses add up to trigger an action potential.

97
Q

What happens when there is spatial summation of EPSP and IPSP?

A

IPSPs negate the reception of an EPSP.

98
Q

What is the difference between temporal and spatial summation?

A

Temporal summation occurs at the same synapse while spatial summation occurs at different synapses, from different neurons.

99
Q

What are three ways of stopping the signal caused by a neurotransmitter?

A
  1. Enzymatic hydrolysis of the neurotransmitter.
  2. Recapture by the presynaptic neuron.
  3. Simple diffusion.
100
Q

What is acetylcholinesterase?

A

An enzyme that destroys acetylcholine in the synaptic cleft.

101
Q

What functions does acetylcholine play a role in?

A

Muscle stimulation, memory formation, and learning.

102
Q

How does acetylcholine work at the neuromuscular junction?

A

At the neuromuscular junction, it binds an ionotropic receptor and induces skeletal muscle contraction; it is degraded by acetylcholinesterase.

103
Q

How does acetylcholine work in cardiac muscle?

A

It binds a metabotropic receptor and reduces the heart rate.

104
Q

What function does glutamate play a role in?

A

The formation of long-term memory.

105
Q

What function do dopamine and serotonin play a role in?

A

They affect sleep, mood, attention, and learning.

106
Q

What functions does nitric oxide play a role in?

A

The relaxation of smooth muscle.

BSCI 1511 (32 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions