Resting Membrane Potential (3) Flashcards Preview

ESA 2 Membranes and Receptors > Resting Membrane Potential (3) > Flashcards

Flashcards in Resting Membrane Potential (3) Deck (32)
Loading flashcards...
0

Why is membrane potential important in cells?

- Provides basis of signalling in nervous system and cells.

1

How is membrane potential measured?

- Microelectrode penetrates cell membrane
- Microelectrode contains conducting solution
- Circuit set up with voltmeter to read potential difference

2

What is the membrane potential?

- Potential inside cell relative to extracellular solution

3

What are the ranges of resting potentials in the following?
- Animal cells
- Cardiac/skeletal cells
- Nerve cells

- Animal: -20 to 90mv
- Cardiac/skeletal: -80 to -90mv
- Nerve: -50 to -75mv

4

Compare the intra/extra cellular concentrations of the following:
- Na+
- K+
- Cl-
- A-

- Na+ 10/145mM
- K+ 160/4.5mM
- Cl- 3/114mM
- A- 167/40mM

5

Give examples of other anions that are transported across cellular membranes.

- Phosphate
- Bicarbonate
- Amino acids
- Charged groups on proteins

6

When at resting potential what movement is there of K+?

- K+ from inside to out via chemical gradient
- K+ from out to inside via electrical gradient
- Balanced so no net movement.

7

What is the Nernst equation and state it.

- Allows calculation of membrane potential at which X is at equilibrium given intra and extracellular X concentrations
- Ex = 61/Z log ((X outside)/(X inside))

8

How much K+ is need to set up resting potential?

- V. small

9

In cardiac and skeletal cells why is their resting potential not exactly Ek?

- Cells are never perfectly selective for K+

10

What is depolarisation?

- Decrease in size of membrane potential from its normal value
- Cell interior is less negative
- e.g. -70mv to -50mv

11

What is hyperpolarisation?

- Increase in size of membrane potential from normal value
- Cell interior becomes more negative
- e.g. -70 to -90mv

12

How do membrane potentials arise?

- Result of selective ionic permeability.
- Changing selectivity will change membrane potential

13

What does increasing the permeability to certain ions result in?

- Moves membrane potential towards the equilibrium potential for that ion

14

What is the equilibrium potential for the following?
- K+
- Na+
- Cl-
- Ca2+

- K+ -95mv
- Na+ +70mv
- Cl- -96mv
- Ca2+ +122mv

15

Which ions' movement can result in hyperpolarisation and why?

- K+ as moves out of cell making it more negative inside the cell
- Cl- as moves into the cell making inside more negative

16

Which ions' movement can result in depolarisation?

- Na+ and Ca2+ as both move into the cell making it less negative

17

What are the 3 types of gating?

- Ligand
- Voltage
- Mechanical

18

What are ligand gated channels?

- Channels that open/close in response to binding of chemical ligand
- e.g. Channels at synapses that respond to extracellular transmitters/Intracellular messengers

19

What are voltage gated channels?

- Channels that open/close in response to a change in membrane potential
- e.g. AP related channels

20

What are mechanical gated channels?

- Opening/closing in response to membrane deformation
- e.g mechanorecepotors.

21

Where can synaptic connections occur between?

- Nerve: nerve/muscle/gland/sensory

22

What is fast synaptic transmission?

- Receptor is also on ion channel
- Transmitter binding causes channel to open

23

What do excitatory transmitters do?

- Open ligand gated channels causing membrane depolarisation

24

What are excitatory synapses permeable to?

- Na+ and Ca2+
- nAChR

25

What is the resulting change in membrane potential known as?

- Excitatory post-synaptic potential (EPSP)

26

How are excitatory synapses controlled?

- Amount of transmitter
- Acetylcholine
- Glutamate

27

What do inhibitory synapses do and what are they permeable to?

- Opening of ligand gated channels to cause hyperpolarisation
- K+ and Cl-

28

What types of transmitters regulate inhibitory synapses?

- Glycine
- Gamma-aminobutyric acid (GABA)

29

What is slow synaptic transmission?

- Receptor and channel proteins are separate.