The Resting Membrane Potential Flashcards Preview

ESA 2- Membranes and Receptors > The Resting Membrane Potential > Flashcards

Flashcards in The Resting Membrane Potential Deck (57):
1

What do all cells have?

An electrical potential difference (voltage) across their plasma membrane

2

What does the membrane potential provide?

The basis of signalling in the nervous system, as well as in many other types of cells

3

How is the resting membrane potential expressed?

As the potential inside the cell relative to the extracellular solution

4

What is the membrane potential of animal cells?

They have negative membrane potentials, that range from -20 to -90mV

5

What is the resting potential of nerve cells?

-50 to -75mV

6

What is resting membrane potentials of smooth muscle cells?

~ -50mV

7

What is the resting membrane potential of skeletal and cardiac muscle cells?

-80 to -90 mV

8

What is the cell membrane selectively permeable to?

Different ions

9

How does the permeability of the membrane to ions occur?

By way of channel proteins

10

What makes the whole cell membrane selectively permeable to ions?

The selectivity of ion channels and the types of channels that are open

11

What dominates the membrane ionic permeability at rest for most cells?

Open K+ channels

12

When is there no net movement of K+?

When the chemical and electrical gradients for K+ are equal and opposite

13

What is true when there is no net movement of K+?

There will be a negative membrane potential

14

What does the resting membrane potential arise because of?

The membrane being selectively permeable to K+

15

What is the intracellular concentration of Na?

~10mM

16

What is the extracellular concentration of Na?

145mM

17

What is the intracellular concentration of K?

160mM

18

What is the extracellular concentration of K?

4.5mM

19

What is the intracellular concentration of Cl?

4mM

20

What is the extracellular concentration of Cl?

114mM

21

What is the intracellular concentration of anions (other can Cl)?

167mM

22

What is the extracellular concentration of anions (other than Cl)

40mM

23

What anions other than Cl are involved in the gradient across the cell membrane?

Phosphate
Bicarbonate 
Amino acids 
Charged groups on proteins

24

In what direction is the K concentration gradient?

From the inside of the cell to the outside of the cell

25

In what direction is the K electrical gradient?

From the outside of the cell to the inside of the cell

26

What is the equilibrium potential for an ion?

The membrane potential at which there is no net movement of the ion across the membrane (the concentration gradient = the electrical gradient)

27

What can be used to calculate the equilibrium potential?

The Nernst Equation

28

What happens in depolarisation?

Membrane potential decreases in size

29

Does depolarisation cause an action potential?

Not necessarily- it may only be a few mV

30

What happens to the cell interior in depolarisation?

It becomes less negative

31

What causes depolarisation?

Opening of Na or Ca channels

32

What happens in hyperpolarisation?

The membrane potential increases in size, falling below resting

33

What happens to the cell interior in hyperpolarisation?

It becomes more negative

34

What causes hyperpolarisation?

Cl or K channels opening

35

What do cells have in reality?

Channels open for more than one type of ion

36

What does the contribution of each ion to the membrane potential depend on?

How permeable the membrane is to that ion

37

What can change a cells membrane potential?

Changes in the cells permeability to a single ion

38

How can be used to cells membrane potential be calculated?

The GHK equation

39

What does the GHK equation show?

That membrane potential depends on the number of open channels open for each ion

40

Where can synaptic connections occur?

Between nerve, muscle, sensory cells and glands

41

How can synaptic transmission be categorised?

Into fast and slow

42

What is the receptor protein in fast synaptic transmission?

A ion chanel

43

What happens in fast synaptic transmission?

The binding of transmitter causes the channel to open

44

What happens in slow synaptic transmission?

The receptor protein and ion channel are separate proteins, that may be linked by G-proteins or intracellular messengers

45

What are the two basic patterns of slow synaptic transmission?

Direct G-protein gating 
Gating via an intracellular messenger

46

What are the characteristics of direct G-protein gating?

Localised
Quite rapid

47

How does gating via an intracellular messenger work?

The G-protein activates an enzyme, which initiates a signalling cascade, through an intracellular messenger or protein kinase which activates the channel

48

What are the characteristics of gating via an intracellular messenger?

Occurs throughout the cell 
Amplification by cascade

49

What do excitatory transmitters do?

Open ligand-gated channels, causing membrane depolarisations

50

What can ligand-gated channels opened by excitatory transmitters be permeable to?

Na, Ca, and sometimes cations in general

51

What is the membrane depolarisation caused by excitatory transmitters called?

Excitatory Post-Synaptic Potential (EPSP)

52

How does EPSP differ from an AP?

It is graded with the amount of transmitter

53

Give two examples of excitatory transmitters

Acetylcholine
Glutamate

54

What do inhibitory transmitters do?

Open ligand-gated channels, causing hyperpolarisation

55

What are ligand-gated channels opened by inhibitory transmitters permeable to?

K or Cl

56

What is the hyperpolarisation caused by inhibitory transmitters called?

Inhibitory post-synaptic potential (IPSP)

57

Give 2 examples of inhibitory transmitters

Glycine
γ-aminobutyric acid (GABA)