Membrane Properties Flashcards

1
Q

What is the difference between a channel and a carrier?

A

A channel is like a tube

A carrier is only open on one side at a time

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2
Q

In the Na/K pump, what does sodium take out of the cell with it?

A

Glucose

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3
Q

Electric potentials are generated across what?

A

The membranes of neurons, and all cells

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4
Q

Why/how is an electric potential generated across membranes?

A

There are difference in the concentrations of specific ions across nerve cell membranes
The membranes are selectively permeable to some of these ions

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5
Q

How are the resting membrane potentials, action potentials, the synaptic potentials and receptor potentials generated?

A

By the channels and active transporters working against each other

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6
Q

In which cell domain are voltage gated channels found?

A

Axonal domain

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7
Q

In which cell domain are ligand-gated ion channels found?

A

Somatodendritic domain

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8
Q

What part of the cell is the action potential generation zone?

A

Axon hillock

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9
Q

Which part of the neuron has only voltage-gated Na and K channels?

A

Axon

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10
Q

Which part of the neuron has voltage-gated Na, K and Ca channels?

A

Nerve termini

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11
Q

Is the concentration of Na higher in the cell, or out of the cell?

A

Outside of the cell

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12
Q

Is the K concentration higher in or out of the cell?

A

In the cell

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13
Q

Where is the potential difference found?

A

In the cell membrane

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14
Q

What two factors influence the actual voltage of a membrane potential?

A

Ionic concentration gradient

Membrane permeability

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15
Q

In almost all cases, the resting membrane potential is primarily due to what?

A

The leak of K ion out of the cell without a counter ion balancing the charge

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16
Q

The rate of ion flux across a membrane is a function of what?

A

The driving force acting on the solute/ion

The permeability of that ion across the membrane

17
Q

The driving force acting on a solute/ion is a function of what?

A

Concentration gradient

Membrane potential

18
Q

Passive flux of all solutes will continue until what occurs?

A

The solute is at equilibrium across the membrane

19
Q

What is the net flux of a solute across a membrane at equilibrium?

20
Q

Ions come into “electrochemical equilibrium” where net flux of the ion may equal zero, and what may still be present?

A

A concentration gradient

21
Q

What is the electrochemical gradient?

A

A combination of the chemical gradient (concentration) and the electrical gradient (membrane potential)

22
Q

How is the membrane potential generated?

A

By differential ionic permeabilities across the membrane - generally due to selective permeability of the membrane for specific solutes

23
Q

As K moves between chambers, it adds a small amount of ___ charge on the one side, and leaves a small amount of ___ charge on the other.

A

Positive

Negative

24
Q

Which equation is used to calculate the equilibrium potential?

A

Nernst equation

25
Voltage is not the same for all cells, and may very over time. Why?
Vm is a function of 2 parameters: 1. Concentration gradients of those ions across the membrane 2. Permeability of the various ions
26
Under resting conditions, what is the most permeable ion?
K
27
What does the Goldman-Hodgkin-Katz equation take into account?
All ion concentrations both inside and outside of the cell
28
Is Ex a real or theoretical value?
Theoretical value - provides a theoretical boundary for Vm if permeability for one ion predominates
29
Vm will vary based on what?
Cell type
30
What does TEPD stand for?
TransEpithelial Potential Difference
31
The magnitude of the TEPD is proportional to what?
The tightness of the tight junctions