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Flashcards in Membrane Properties Deck (31)
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1

What is the difference between a channel and a carrier?

A channel is like a tube
A carrier is only open on one side at a time

2

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

Glucose

3

Electric potentials are generated across what?

The membranes of neurons, and all cells

4

Why/how is an electric potential generated across membranes?

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

5

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

By the channels and active transporters working against each other

6

In which cell domain are voltage gated channels found?

Axonal domain

7

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

Somatodendritic domain

8

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

Axon hillock

9

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

Axon

10

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

Nerve termini

11

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

Outside of the cell

12

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

In the cell

13

Where is the potential difference found?

In the cell membrane

14

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

Ionic concentration gradient
Membrane permeability

15

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

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

16

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

The driving force acting on the solute/ion
The permeability of that ion across the membrane

17

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

Concentration gradient
Membrane potential

18

Passive flux of all solutes will continue until what occurs?

The solute is at equilibrium across the membrane

19

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

0

20

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

A concentration gradient

21

What is the electrochemical gradient?

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

22

How is the membrane potential generated?

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

23

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.

Positive
Negative

24

Which equation is used to calculate the equilibrium potential?

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