Lecture 3 Flashcards

1
Q

When K+ leak channels are placed…

A
  • membrane becomes permeable to k+
  • flow along an chemical gradient
  • making inside more negative
  • electrochemical gradient will attract k+ ions back in (opposite attracts)
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2
Q

The intracellular and extracellular environements are in _______ & _________ disequillibrium

A
  1. electrical
  2. chemical
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3
Q

why are ions unevenly distributed across cell membranes

A
  • due to the selective permeability of the cell membrane to different ions
  • based on the presence of ion channels and transporters in the plasma membrane
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4
Q

give K+ concentrations

A

ICF: 140mM
ECF: 4mM

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5
Q

give Na+ concentrations

A

ICF: 15mM
ECF: 145mM

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6
Q

give Ca2+ concentrations

A

ICF: 0.001mM
ECF: 1.8mM

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7
Q

give Cl- concentrations

A

ICF: 4mM
ECF: 115mM

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8
Q

give P concentrations

A

ICF: 40mM
ECF: 2mM

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9
Q

give protein concentrations

A

ICF: 4mM
ECF: 0.2mM

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10
Q

What is the major contributor to cell negativity?

A

K+

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11
Q

Define the resting membrane potential (RMP)

A
  • the net charge difference between the intercellular fluid and extracellular fluid at rest
  • due to the unequal distribution of ions on each side of the membrane that results in both electrical and concentration gradient
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12
Q

membrane potential

A

measured from inside the cell relative to the outside

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13
Q

What is the equilibrium potential

A

The potential where the electrical gradient opposes the concentration gradient and there is no net movement of the ion

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14
Q

When Vm = Ex

A

Equilibrium is achieved

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15
Q

The nernst equation calculates what

A

Equilibrium potential of an ion (Ex = (61/Z) log Iout/Iin)

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16
Q

The GHK equations predicts what

A
  • Predicts the membrane potential that results from all ions that can cross the membrane
  • based on combined contributions of concentration gradients and relative membrane permeability for each ion
17
Q

Most cells are ______ times more permeable to k+ than NA+

A

40

18
Q

If the membrane potential becomes less negative than the resting potential the cell _________

A

Depolarizes

19
Q

If the membrane potential becomes more negative, the cell ______________

A

Hyperpolarizes

20
Q

What contributes to the negativity in the cell

A
  1. Sodium potassium pump
  2. K+ leak channels
  3. Negatively charged proteins