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Histo (VM1 Fall) > Exam 2 - Lecture 20 (Membrane Potential 1) > Flashcards

Exam 2 - Lecture 20 (Membrane Potential 1) Flashcards

1
Q

What is the RMP? (definition and number)

A

Potential difference across the membrane; net charge on the inside of the plasma membrane compared to the outside.
-65 mV

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2
Q

What does the Goldman equation calculate?

A

The membrane potential

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3
Q

Which side of the cell is NORMALLY negative?

A

inside

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4
Q

What does the RMP reflect?

A

Uneven distribution of ions across the plasma membrane by the electrochemical gradients of the Na/K pump, selective ions, and large intracellular ions that cannot leave the cell.

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5
Q

What is another name for the Na/K pump?

A

ATPase pump

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6
Q

At what rate does the Na/K pump work?

A

continuously

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7
Q

What ions are selectively permeable to the membrane?

A

K, Cl, Na

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8
Q

What type of channels do K and Cl use?

A

Nongated (leak) channels

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9
Q

How does Na get into the cell?

A

We are not sure

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10
Q

What is important about the large intracellular ions of the cell?

A

They are too large to exit and are negatively charged (anions), so contribute to negative charge of the inside of the cell

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11
Q

Which way does K move across the membrane?

A

In; cannot move out

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12
Q

What happens when electrical force inside of the cell equals the diffusional force outside of the cell?

A

No ions diffuse into or out of the cell

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13
Q

What is depolarization?

A

Decrease in potential difference across the plasma membrane, going to more positive, approaching 0 mV.

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14
Q

What is overshoot?

A

Potential difference > 0mV

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15
Q

What is repolarization?

A

Return of the membrane to its normal RMP.

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16
Q

What is hyperpolarization?

A

Increase in potential difference across the PM, going to more negative, away from the RMP

17
Q

What are the 2 steps by which a sensory receptor transduces a signal (aka converts sensory stimulus to electrical signal)?

A
  1. Sensory stimulus generates receptor potential

2. Receptor potential leads to AP

18
Q

What are the 2 ways by which a sensory stimulus generates receptor potential?

A
  1. Opens specific ion channels

2. Opening of channels leads to depolarization and hyperpolarization of receptor membrane

19
Q

What 3 specific ion channels are opened when a sensory stimulus occurs?

A
  1. Mechano-gated Na+ channels
  2. Heat-gated Na+ channels
  3. Cold-gated Na+ channels
20
Q

What is a potential produced by sensory transduction?

A

A depolarizing event resulting from inward current flow

21
Q

What is receptor potential?

A

Depolarizing potential of receptor membrane

22
Q

What happens to electrical potential across the plasma membrane for a brief period when the receptor potential is generated?

A

Brief reversal in electrical potential

23
Q

What happens during the brief reversal in electrical potential once a stimulus occurs?

A

Inside of the cell is positive, outside of the cell is negative

24
Q

When is an AP generated?

A

When the receptor potential goes over the threshold potential

25
Q

What is the threshold potential?

A

-55 mV

26
Q

What 2 things does the generation of an AP require?

A
  1. Voltage-gated Na+ channels

2. Voltage-gated K+ channels

27
Q

Does the sensory receptor itself have any voltage gated channels?

A

No; it only has mechano-, heat- and cold-gated

28
Q

What are the 3 cycles that the VG Na+ channel goes through during an AP and what happens during each?

A
  1. Resting - channel closed
  2. Activated - channel open
  3. Inactivated - channel closed
29
Q

When does Na+ cross the membrane? (During which VG Na+ channel cycle?)

A

Only crosses during activated state (channels open)

30
Q

What must happen to inactivated Na+ channels before they can open again?

A

They must be de-inactivated to the resting state

31
Q

What channels open when the receptor potential goes over threshold and at what rates?

A

ALL VG Na+ (rapid) and K+ channels (slowly)

32
Q

What happens when Na+ channels rapidly open?

A

Na+ influx, then stop

33
Q

What happens when K+ channels slowly open?

A

K+ outflux, then stop

34
Q

What happens to Cl influx vs. outflux during an AP?

A

Does not really move in or out

Histo (VM1 Fall) (27 decks)

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