Brainscape's Knowledge GenomeTM

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


See full index

Vertebrate Physiology > Chapter 6 > Flashcards

Chapter 6 Flashcards

1
Q

What are graded potentials?

A

small changes in the membrane potential that occur in varying grades (degrees of magnitude or strength.

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

The stronger the triggering event,___________

A

the larger the graded potential

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

What creates the resting potential in nerves and muscle cells?

A

the sodium potassium differences.

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

What does it mean that graded potentials are decremental?

A

graded potentials occur at one point on the membrane and can be transferred to other points by passive current flow, but usually diminish.

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

What are action potentials?

A

brief reversals of membrane potential brought about by rapid changes in membrane permeability. These changes are spread throughout the entire membrane and do not diminish in value along the length of the cell.

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

What is polarization?

A

establishment of the potential, separation of opposite charges (resting potential)

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

What is depolarization?

A

the reduction of the membrane potential from its resting potential toward 0mV or to a slightly positive potential.

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

What is repolarization?

A

the membrane returns to its resting potential after being depolarized.

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

What is hyperpolarization?

A

the membrane potential is greater than the resting potential.

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

What is threshold potential?

A

the value t which the membrane spontaneously depolarized (-55 to -50 mV).

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

What happens once threshold is reached?

A

the membrane potential rapidly moves up to +30mV (depolarization).
The membrane becomes 600 times more permeable to sodium than potassium.

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

What are leak channels?

A

passive ion channels

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

What are voltage gated channels?

A

channels that open or close in response to changes in the membrane potential. These play a major role in the formation of an action potential.

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

What are chemical messenger gated channels?

A

change conformation when bound by a specific chemical messenger.

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

What are mechanically gated channels?

A

respond to stretching or other mechanical activity.

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

What are thermally gated channels?

A

open in response to cold or heat.

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

What does the triggering event initiate?

A

movement of sodium ions into the cell, bringing in positive charges, which further depolarizes the membrane. This continues until threshold is reached.

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

How permeable is the membrane to sodium and potassium at resting state?

A

the membrane has more leak channels for potassium than for sodium, so the membrane is 50-75X more permeable to potassium than sodium at rest.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

How fast do the potassium channels open relative to that of sodium?

A

much more slowly than the sodium channels.

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

What does the rapid influx of sodium into the cell do?

A

eliminates the negative charge and makes the inside more positive than the outside.

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

What happens to the sodium and potassium channels at +30mV?

A

the sodium channels become inactive. The slow opening potassium channels are finally open, so permeability to potassium increases when the sodium channels are inactivated. So, potassium rushes out of the cell, down its concentration gradient, which restores the negativity of the inside portion of the plasma membrane. (repolarization).

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

What causes hyperopolarization?

A

the slow closing potassium channels go past the -70mV mark before closing.

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

How does local current flow occur?

A

starts at the axon hillock, The membrane polarity is reversed, the inactive areas of the membrane have the opposite charge. The positive charges are pulled toward the negative charges, which opens up voltage-gated channels along the membrane and depolarizes along the length of the axon.

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

What happens to the areas left behind by the repolarization?

A

they become less permeable to sodium and are said to be refractory.

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

What influences the rate of conduction?

A

the diameter of the axon. As the axon gets bigger, there is less resistance.

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

Where does saltatory conduction occur?

A

in myelinated fibers only.

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

What is the distance between nodes on the neuron?

A

1 mm, which is optimal for transmission.

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

Why is saltatory conduction faster than local current flow?

A

a reduction in the number of voltage-gated channels that need to be opened.

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

What do not appear beneath schwann cells?

A

no voltage-gated channels for depolarization and repolarization of the membrane.

30
Q

What is wallerian degeneration?

A

occurs when the axon is cut. Schwann cells phagocytose the dead axon, then build a tube for the new axon to grow through. This occurs in the PNS. Oligodendrocytes do not behave this way when a CNS axon is cut.

31
Q

What is multiple sclerosis?

A

a disease in which demyelination occurs (myelin is replaced by scars.

32
Q

Describe the all or none law

A

if any portion of the membrane is depolarized to threshold, the rest of the membrane will depolarize and an action potential will be generated.
The height of the action potential is always the same despite the strength of the initial stimulus.
intensity of signals is transmitted by increased frequency of action potentials, among other things.

33
Q

What does the refractory period allow for?

A

unidirectional travel of nerve impulses.
One portion of the membrane is incapable of transmitting a second impulse for a brief time.
during this time, the action potential moves away from the site and cannot trigger a retrograde event.

34
Q

What is the absolute refractory period?

A

occurs when the sodium channels are inactive, closed and incapable of opening.
during this time, an action potential cannot be generated.

35
Q

What is the relative refractory period?

A

the time frame when a very strong stimulus can generate an action potential. This occurs after the inner sodium gates have opened, but the potassium gates are still closing.

36
Q

What do refractory periods establish?

A

the maximum frequency at which a nerve can generate impulses.

37
Q

What is the cell body?

A

the region of the cell that contains the nucleus.

38
Q

What are dendrites?

A

the region of the neuron that receives impulses from another region, or in the case of sensory nerves, the part of the neuron that generates impulses.

39
Q

What is the axon?

A

a tubular extension that transmits action potentials away from the cell body.

40
Q

What are collaterals?

A

multiple branches off of the axons.

41
Q

What is the axon hillock?

A

the site of initiation of action potentials. Has the lowest threshold for activation as a result of having the greatest concentration of sodium voltage gated channels.

42
Q

What is the axon terminal?

A

release chemical messengers to affect the next neuron.

43
Q

What is myelination?

A

insulates neurons.

44
Q

What are nodes of Ranvier?

A

unmyelinated gaps of axon.

45
Q

What is an electrical synapse?

A

involves the spread of action potential via gap junctions. Cannot be modified.

46
Q

What is a chemical synapse?

A

a chemical message is secreted by one neuron and acts on another neuron.

47
Q

What is the synaptic terminal?

A

the swelling at the end of the axon that contains synaptic vessicles.

48
Q

What do the synaptic vessicles contain?

A

neurotransmitters.

49
Q

How does exocytosis of the synaptic vesicles occur?

A

when the action potential reaches the synaptic knobs, voltage-gated calcium channels open in response to the passing action potential and calcium ions move into the synaptic knob, causing exocytosis of the synaptic vesicles.

50
Q

What is an EPSP?

A

excitatory postsynaptic potential.
when an excitatory synapse has neurotransmitters that initiate the opening of sodium, and to a lesser extent, potassium channels.

51
Q

What is an IPSP?

A

inhibitory postsynaptic potential.
when an inhibitory synapse has neurotransmitters that increase the membrane’s permeability to potassium or chloride. This hyperpolarizes the membrane, thus making it more difficult to move the post-synaptic neuron to threshold.

52
Q

What is GPSP?

A

the grand postsynaptic potential.

depends upon the sum of the EPSPs and the IPSPs

53
Q

What is temporal summation?

A

when EPSP or IPSP from one source occurs close enough together in time to further hypopolarize a neuron.

54
Q

What is spatial summation?

A

when EPSPs or IPSPs from different sources further hypopolarize a neuron.

55
Q

To end a signal occurring at a chemical synapse, ______________________

A

the amount of neurotransmitter must be reduced.

56
Q

What are the ways that a signal occuring at a chemical synapse can end?

A

Neurotransmitters can be reuptaken by the presynaptic neuron, or taken up by a glial cell.
neurotransmitters can also be degraded in the synpatic cleft.

57
Q

Describe neuropeptides.

A

act locally in lower concentrations than neurotransmitters and bring about long-term change.
bind at nonsynaptic sites and alter the neuron’s response to synaptic input, either increasing or decreasing the sensitivity of a postsynaptic neuron to a particular synapse.

58
Q

What do neuropeptides do, specifically?

A

they alter downstream events to modify the sensitivity of a neuron to a neurotransmitter. Thought to be accomplished by second messenger system.

59
Q

What is an example of a neurotransmitter?

A

CCK, cholecystokinin, which initiates contraction of the gall bladder an din the CNS is thought to play a role in satiety.

60
Q

What is parkinson’s disease?

A

a deficiency in dopamine in the brain.

61
Q

What is myasthenia gravis?

A

loss of acetylcholine receptors on skeletal muscle.

62
Q

What can drugs do?

A
  1. alter synthesis, storage, transport, and release of neurotrasmitters.
  2. modify the interaction of the neurotransmitter with its receptor at the synapse
  3. alter the reuptake by the presynaptic neuron or destruction of the neurotransmitter.
    replace a deficient neurotransmitter.
63
Q

What can L-dopa do?

A

cross the BBB.

64
Q

Describe the function of the tetanus toxin

A

prevents the release of GABA, an IPSP generator. Loss of inhibition results in tetanic paralysis of skeletal muscles.

65
Q

what do local anesthetics do?

A

block sodium channels and thus block action potentials.

66
Q

How do gap junctions help with direct intracellular communication?

A

allow for exchange of ions and small molecules.

includes cardiac muscle and some smooth muscle cells.

67
Q

Describe transient direct linkup of cells in direct intercellular communication.

A

chemical messengers are bound to the surface of the cell, chemical communication occurs when cells come in contact with each other.
Predominantly in the immune system.

68
Q

Describe paracrine secretion

A

local chemical messengers exert their effect primarily on neighboring cells.
distributed via simple diffusion and remain in the interstitial space.
released in minute amounts.
released in response to a specific event.
histamine interferons, growth factors.

69
Q

Describe neurotransmitter secretion.

A

very short-ranged
released into the interstitial space between a nerve and its target
targets are either another nerve, a muscle cell, or a glandular cell.

70
Q

Describe hormone secretion.

A 
long-ranged. 
transmitted by the blood. 
can have more than one target tissue. 
are secreted in relatively large amounts
released in response to signals.
71
Q

Describe nonhormone secretion

A

released into the blood by neurosecretory neurons.

have much longer range of effects than neurotransmitters.

Vertebrate Physiology (9 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions