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Physiology 1 > ionic movement, membrane potentials and action potentials > Flashcards

ionic movement, membrane potentials and action potentials Flashcards

1
Q

the amount of ions able to cross a membrane is based on what?

A

number and activity of transport proteins

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2
Q

Conductance of ions is based on what?

A

-the number of channels that are open

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3
Q

what are the two kinds of exclusion ion channels have because they are so specific?

A
  • size exclusion

- charge exclusion

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4
Q

how does charge exclusion work?

A

-interior of the channel will be lined with charged amino acids prevent like ions from crossing

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5
Q

what are leak channels open?

A

-they are always open

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6
Q

what is an example of leak channels?

A

K+ and Cl- channels

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7
Q

what are gated channels?

A

closed until a stimulus opens them

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8
Q

what can act as a stimulus for gated channels?

A
  • ligands
  • second messenger
  • voltage
  • light
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9
Q

when is a ligand gated channel open and when does ir close?

A
  • opens when proper ligand binds to it

- remains open until ligand is removed

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10
Q

what is an example of second messenger gated channels?

A
  • calcium channels in smooth muscle cells
  • Angiotensin II binds to its receptor and causes the production of IP3
  • IP3 binds to and opens calcium channels
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11
Q

what is an example of a voltage gated channel?

A

-sodium channel in muscles

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12
Q

which type of channel would have the most rapid effect on ionic flow?

A

ligand gated

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13
Q

which type of channel could lead to a more varied cellular response?

A

2nd messenger gated

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14
Q

what happens when ions move down a concentration gradient?

A

they generate a current

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15
Q

movement of ions continues until when?

A

-when they reach their equilibrium potential

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16
Q

what is the equilibrium potential?

A

-potential difference required to stop ion movement

17
Q

what do ions move in response to?

A

concentration and charge

18
Q

what would you use the Nernst equation for?

A

determining the equilibrium potential

19
Q

the sign of the equilibrium potential is with respect to what?

A

the interior of the cell

20
Q

what is RMP?

A
  • resting membrane potential

- charge difference across cell membranes due to concentration gradients of permeant ions

21
Q

what is the RMP in neurons? in skeletal muscle?

A
  • 70 in neurons

- 90 in skeletal muscle

22
Q

increasing permeability of what to 100% would cause the greatest change in RMP?

A

calcium

23
Q

what is an action potential?

A
  • rapid changes in membrane potential

- depolarization from and repolarization to RMP

24
Q

are all action potentials for the same cell type the same?

A

-yea hella similar

25
Q

what does it mean by all action potentials are propagated?

A

-they have to move from one site to the next!

26
Q

what does it mean by all action potentials are all or nothing?

A

-if they reach specific voltage, then it will occur

27
Q

what happens are local depolarization?

A
  • membrane moves closer to zero mV

- losing polarity

28
Q

what is the threshold?

A
  • about -60mV

- point at which AP has to occur

29
Q

what is overshoot?

A

-interior becomes positive relative to the outside

30
Q

what is repolarization?

A

-membrane begins to move back towards zero and more negative

31
Q

what is hyperpolarization?

A

-membrane becomes more negative past the RMP

32
Q

RMP is maintained by what?

A

K+ leak currents (K+ conductance)

33
Q

what is necessary for RMP? what is moved?

A
  • Na-K ATPase

- 3 Na+ out for 2 K+ in to make inside more negative

34
Q

in what cells is RMP not stable?

A

-rhythm generating cells (intestine and heart cells)

35
Q

what is the major contributor to the RMP?

A

K+ current through leak channels

36
Q

what is responsible for the depolarization of action potentials?

A

voltage gated Na+ channels

37
Q

local depolarization is stimulated by what?

A

ligand gated Na+ channels

38
Q

local hyperpolarization is stimulated by what?

A

ligand gated Cl- channels

Physiology 1 (6 decks)

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