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Physiology - Principles > The Resting Membrane Potential - Lecture 4 > Flashcards

The Resting Membrane Potential - Lecture 4 Flashcards

1
Q

Fill in the blank
The Plasma membrane of all cells are _ _ _ _ _ _ _ _ _
_ _ _ _ _ _ _ _ _ _ _ _

A

Polarised Electrically

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2
Q

What is the symbol for a membrane potential?

A

Em

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3
Q

What is the definition of membrane potential?

A

A separation of opposite charges across the membrane.

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4
Q

What are the units used for membrane potentials?

A

Units: mV (1/1000 volt)

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5
Q

Is the membrane itself charged during membrane potentials?

A

No - Em refers to the difference in charge between the thin layers of ECF and ICF located next to the inside and outside of the membrane

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6
Q

Why is the Em different between different cells?

A

Em relies on the permeability of key ions

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7
Q

What is a rapid transient change in their membrane potential?

A

An Action potential

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8
Q

What cells can produce an action potential?

A

Nerve and muscle cells

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9
Q

What is a resting membrane potential?

A

The constant membrane potential while the cell is at rest

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10
Q

What ions is the cell membrane permeable to?

A

Potassium

Sodium - only very slightly.

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11
Q

What fluid is sodium found in most abundance?

A

Extracellular fluid - It is generally transported into the cell

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12
Q

What fluid is potassium found in most abundance?

A

Intracellular fluid

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13
Q

What fluid is chlorine found in most abundance?

A

Extracellular

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14
Q

How is the Em created?

A

Due to unequal distribution of ions and their selective movement through the plasma membrane

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15
Q

What is the concentration gradient of Potassium?

A

Out of cells

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16
Q

What is the concentration gradient of Sodium?

A

Into cells

17
Q

How many more times is Potassium permeable to the membrane than sodium at the resting potential?

A

100 more times

18
Q

What is the cell membrane impermeable to?

A

Large negatively charged intracellular proteins

19
Q

What is the effect of Potassium movement on the Em

A

Inside the cell becomes more negative. Outside the cell becomes more positive

20
Q

What are the two opposing forces acting on Potassium?

A

The concentration gradient (tending to move K+ out of the cell)
The electrical gradient (tending to move K+ into the cell)

21
Q

When does Potassium movement stop?

A

When both electrical gradient and concentration gradient are at equilibrium

22
Q

What is the symbol for the equilibrium potential of Potassium?

A

Ek

23
Q

What value of the Ek of Potassium?

A

-90mV

24
Q

What is the nernst equation used for?

A

Is it used for calculating the equilibrium potential for any given ion

25
Q

What is the Nernst equation?

A

Eion= 61log10 [Conc ionOutside]
———————-
[Conc Ion Inside]

26
Q

What occurs when sodium is transported into the cell

A

The Extracellular fluid becomes more negative
Inside the cell becomes more positive
Concentration gradient into the cell

27
Q

What occurs as permeability to an ion increases?

A

There is a tendency for that ion to drive membrane potential towards the ion’s own equilibrium potential.

28
Q

Is the membrane potential positive or negative at rest?

A

Negative

29
Q

Is the membrane potential at rest close to that of K or Na ?

A

Closer to Potassium at rest

30
Q

What is the Golman-Hodkin- Katz equation for?

A

It is an equation used to calculate the membrane potential of a cell - It takes into account all ions present and their permeabilities

Em = 61log10 PermxConc Ionout
————————–
PermxConcion In

31
Q

In the sodium potassium pump what is the ratio of Sodium exchanged for Potassium exchanged?

A

3 Sodium exported

2 Potassium entering

32
Q

What type of current does the Sodium Potassium pump create?

A

It creates a hyperpolarising current

33
Q

What is the value of E (na)?

A

+ 61 mV

34
Q

What is the value of E(k) ?

A

-90mV

35
Q

In the pancreas what are changes in membrane potentials linked to?

A

Changes in Em linked to secretion of insulin from pancreatic Beta-cells.

36
Q

What is the Goldman-Hodgkin-Katz equation?

A

Vm = Perm of ion1[Ion1Outisde] + Perm of ion2[Ion2Outside]
—————————————————————–
Perm of ion1[Ion1Inside] + Perm of ion2[Ion2Inside]

Physiology - Principles (8 decks)

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