Cell Physiology 1: Membrane Potentials Flashcards Preview

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Flashcards in Cell Physiology 1: Membrane Potentials Deck (53)
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1
Q

electrical signalling is the ability of ____ and ___ cell types to ___ and ___ electrical signals

A

muscle and nerve; generate and carry

2
Q

electrical signalling is dependent on distribution of ___ across a cell membrane

A

ions

3
Q

total body water is approximately what % of a human’s body weight?

A

50-70%

4
Q

what amount of of total body water is intracellular fluid?

A

2/3 (two thirds)

5
Q

what amount of total body water is extracellular fluid?

A

1/3

6
Q

what percent of extracellular fluid is interstitial fluid?

A

80%

7
Q

what percentage of extracellular fluid is plasma?

A

20%

8
Q

the concentration of K+ ions is higher ___ (inside or outside) the cell

A

inside

9
Q

the concentration of Na+ ions is higher __ (inside or outside) the cell

A

outside

10
Q

the concentration of Cl- is higher __ (inside/outside) the cell

A

outside

11
Q

the concentration of non-Cl- anions is higher ___ (inside/outside) the cell

A

inside

12
Q

the concentration of Ca2+ ions is higher __ (inside/outside) the cell

A

outside

13
Q

how are the ion concentrations across a cell membrane maintained?

A

the lipid bi-layer doesn’t allow free passage of ions

14
Q

the lipid bi-layer is permeable to ____ but not __

A

fat soluble things; water soluble things

15
Q

the core of the lipid-bilayer is very __ (hydrophilic or hydrophobic)

A

hydrophobic

16
Q

where do the concentration gradients across cell membranes come form in the first place?

A

proteins that move ions across by active transport

17
Q

what is the name of the protein that pumps Na+ and K+ across the cell membrane

A

sodium/potassium ATPase

18
Q

the sodium potassium pump actively transports __ (#) Na+ __ (in/out) and __(#) K+ ___ (in/out)

A

3 Na out; 2K in

19
Q

the sodium potassium pump moves Na/K ___ (down/against) their concentration gradient

A

against

20
Q

what energy source is used for the sodium potassium pump to actively transport ions?

A

ATP hydrolysis

21
Q

Describe the steps of the transport done by the sodium potassium pump

A
  1. Protein opens to the inside and 3 sodium bind
  2. protein is phosphorylated by ATP (ATP becomes ADP)
  3. phosphorylation caused protein to open to the outside and release Na+
  4. the open protein can then bind 2 K
  5. dephospho rylation of the protein causes it to open to the inside and release the K+
22
Q

T/F the sodium potassium pump is constantly working in the background, even when nothing else is happening in the cell

A

true

23
Q

what is the benefit of the protein needing to be either phosphorylated/dephosphorylated to change direction of opening?

A

prevents protein from being open to both sides, allowing regulation of which ad how many ions come in/out

24
Q

what type of proteins are largely involved in creating electrical gradients?

A

ion channels

25
Q

T/F ion channel proteins can be continuously open

A

true

26
Q

T/F ion channel proteins only allow 1 specific type of ion to pass

A

true

27
Q

t/f ion channel proteins have gates that can close

A

true

28
Q

channel-mediated movement is both __ and __

A

very fast and passive!

29
Q

channel proteins allow for __ diffusion down a ___ gradient

A

passive;

electrochemical

30
Q

b/c ion channels are gated and selective they can change their __ to different ions independently

A

permeability

31
Q

the extracellular fluid has a very slight __ charge

A

positive

32
Q

the intracellular fluid have a very slight __ charge

A

negative

33
Q

the very small imbalance of charge across a cell membrane creates a __

A

resting potential

34
Q

charge imbalance across a membrane causes a ___ force, promoting the __ of ions across a membrane

A

electro-motive; movement

35
Q

T/F charge distribution affects the movement if ions across a membrane

A

true

36
Q

the charge imbalance across a membrane that creates an electro-motive force results in a membrane __

A

potential

37
Q

the membrane potential affects the distribution of ions by __

A

electrostatic attraction and repulsion

38
Q

explain how an electrochemical gradient is made across the cell membrane

A

the movement of ions down their concentration gradients will eventually create an electrical gradient that will cause an ion to move against its concentration gradient until equilibrium is reached

39
Q

what is the equilibrium potential of sodium?

A

+60 mV

40
Q

what is the equilibrium potential of potassium?

A

-90mV

41
Q

the equilibrium potential of sodium being +60mV means __

A

that the inside of the cell will be +60mV more positive than the outside

42
Q

the equilibrium potential of potassium being -90mV means__

A

that the inside of the cells will be -90mV more negative that the outside of the cell

43
Q

what equation is used to calculate equilibrium potential?

A

Nernst

44
Q

what is an equilibrium potential?

A

the electrical gradient (voltage) needed to balance the concentration gradient

45
Q

t/f leak ion channels are constantly working as background function in cells

A

true

46
Q

if you want to calculate resting potential of a cell considering all ions that are capable of crossing the membrane, what equation would you use?

A

the GHK

47
Q

what is th resting potential of muscle and nerve cells?

A

-70mV

48
Q

why is the resting potential closer to the equilibrium potential of potassium than sodium?

A

the resting permeability of potassium is much (25x) greater than that of sodium

49
Q

at the resting potential, the K electrochemical gradient is __ (inward/outward)

A

outward

50
Q

how can we change the resting potential value?

A

by changing the permeability of ions

51
Q

what would happen to the resting potential if we increased the permeability of K? what is this process called?

A

K will leave cell, causing it to become more negative, thus moving more towards the equilibrium potential of K. Hyperpolarization

52
Q

what would happen to the resting potential if we increased the permeability to Na? what is this process called?

A

Na will enter cell, becoming more +, this moving towards ENa. Depolarization

53
Q

when changing the permeability, what equation can be used to predict the new membrane potential?

A

GHK