Pharmacology 5 - Action Potentials Flashcards Preview

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Flashcards in Pharmacology 5 - Action Potentials Deck (61)
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1

What is depolarisation?

The membrane potential becomes less negative (more positive)

2

What is hyper polarisation?

Membrane potential becomes more negative

3

What in general causes changes in membrane potential?

Ionic movements

4

Name for movement of ion into a cell?

Influx

5

Name for movement of ion out of a cell?

Efflux

6

What drives the passive movement of an ion through an ion channel?

The electrochemical gradient

7

What are required to allow movement of ions across membranes?

Ion channels (Transporters)

8

What aids the movement of Na+?

Sodium-selective channels

9

In what direction does Na+ flow?Why? (3)

InwardlyThe concentration gradient is inwardsThe electrical gradient is inwardsThe membrane potential is negative to the equilibrium potential for Na+

10

What is the membrane potential?

The difference in electrical potential between the interior and anterior aspects of the cell

11

What is the approximate membrane potential for many neurones?

-80mV

12

What is the equilibrium potential?

membrane potential where the net flow through any open channels is 0.

13

What is the driving force for Na+ influx equal to?

(Vm - Ena)

14

Since the driving force for Na+ is negative, in what direction does Na+ move?

Inwards

15

What is conductance?

The degree to which an object conducts electricity

16

Ina = (sodium current)?

Ina = gNa (Vm - Ena)Na+ current = Na+ conductance X driving force

17

What enables the movement of K+?

Potassium-selective channels

18

In what direction does K+ flow?Why? (2)

Outwardsthe concentration gradient is outwards (has an energy that exceeds that of the electrical gradient (which is inwards))The membrane potential is positive to the equilibrium potential for K+

19

What is the equilibrium potential of Na+?

+60mV

20

What is the equilibrium potential of K+?

-100mV

21

What is the driving force of K+ efflux equal to?

(Vm - Ek)

22

In terms of the driving force, why does K+ move inwards?

The driving force is positive (+20mV)

23

Does K+ channel opening cause hyper polarisation or depolarisation?

Hyperplorisation

24

Does Na+ channel opening cause hyper polarisation or depolarisation?

Depolarisation

25

What are some factors that can open gated ion channels?

Membrane voltage (voltage-gated ion channels)Chemical substances (ligand-gated ion channels)Physical stimuli e.g. mechanical, thermal

26

What are the 2 ion channels responsible for the action of action potential in neurones?

Voltage-activated Na+ channels (Nav) - depolarising Voltage-activated K+ channels (Kv) - hyper polarising

27

What side of a cell membrane (inside or outside) is positively and negatively charged?

Inside = negativeOutside = positive

28

How many glycoprotein subunits make up the K+ channels?

4

29

How many glycoprotein subunits make up the Na+ channels?

1 (acts as if there is 4 separate parts)

30

When is an action potential?

the change in electrical potential associated with the passage of an impulse along the membrane of a muscle cell or nerve cell.