Session 3 - Resting Membrane Potential

Question 1

How do we measure a membrane potential?

Answer 1

• Use a micro-pippette to penetrate cell membrane

- Micro-electrode then used to measure voltage inside relative to the voltage outside of the cell

Question 2

Give the range of values in which an animals cells membrane potentials lie in

Answer 2

-20mV to -90mV

Question 3

Which tissues have the highest membrane potential in animal cells?

Answer 3

Skeletal and Cardiac muscle

Question 4

What is the range of values that a nerve cells membrane potential will lie?

Answer 4

-50mV to -75mV

Question 5

How does a membrane acheived selective permeability?

Answer 5

Differing types of ion channels which specific to one or a few ions that are open or closed allowing the membrane to be selectively permeable

Question 6

Name the concentrations of sodium intra and extracellularly

Answer 6

Intra - 10mM

Extra - 145mM

Question 7

Name the concentration of Potassium ions intra and extracellularly

Answer 7

Intra - 160mM

Extra - 4.5mM

Question 8

Name the concentration of Chloride ions intra and extracellularly

Answer 8

Intra - 3mM

Extra - 114mM

Question 9

Name the concentration of Anions intra and extracellularly

Answer 9

Intra - 167mM

Extra - 40mM

Question 10

What is the equilibrium potential for an ion?

Answer 10

The membrane potential at which the ions are at an equilibrium between their electrochemical and diffusing gradients

Question 11

Define Depolarisation

Answer 11

A decrease in membrane potential, so that the inside of the cell becomes less negative

Question 12

Define Hyperpolarisation

Answer 12

Increase in membrane potential, such that the inside of the cell become more negative

Question 13

What is the usual result of opening Sodium or Calcium ions?

Answer 13

Depolarisation

Question 14

What is the usual result of opening Potassium or Chloride ion channels?

Answer 14

Hyperpolarisation

Question 15

What are ligand-gated channels?

Answer 15

Channel is open or closed by the binding of a chemical ligand either extra or intracellularly

Question 16

What are Voltage-gated channels?

Answer 16

Channels that open of close in response to a change in membrane potential

Question 17

What is fast synaptic transmission?

Answer 17

The receptor is also a ligand-gated channel?

Question 18

What is an Excitatory Postsynaptic Potential (EPSP)?

Answer 18

When transmitters such as Sodium and Calcium enter a cell causing depolarisation and excitation of the cells

Question 19

What is an Inhibitory Postsynaptic Potential (IPSP)?

Answer 19

When the entrance of transmitters such as Potassium of Chloride into a cell causes inhibition and hyperpolarisation

Question 20

What is Slow Synaptic Transmission?

Answer 20

When the receptor is not an ion channel, involving the use of a GTP binding protein

Question 21

Name the two types of Slow synaptic transmission

Answer 21

• Within a membrane (G-protein diffuses laterally and binds to ion channel)
• Intracellular messenger (G-protein binds to an enzyme causing a signalling cascade

Question 22

What is a membrane potential?

Answer 22

The electrical potential difference across a plasma membrane