Neural signalling - interpreting oscilloscope traces: skills

Question 1

What is a membrane potential?

Answer 1

The difference in charge between one side of a membrane and the other, also known as potential difference or voltage.

It is crucial for neuron function and signaling.

Question 2

How can membrane potentials be measured in neurones?

Answer 2

By placing electrodes on each side of the membrane.

This method allows for direct measurement of voltage changes across the membrane.

Question 3

What is an oscilloscope?

Answer 3

An electronic test instrument that graphically displays varying signal voltages.

It is commonly used in laboratories to visualize electrical signals.

Question 4

What does the x-axis represent on an oscilloscope display?

Answer 4

Time in milliseconds.

This allows for analysis of how voltage changes over time.

Question 5

What does the y-axis represent on an oscilloscope display?

Answer 5

Membrane potential in millivolts.

This indicates the voltage level of the membrane potential.

Question 6

What does a resting potential look like on an oscilloscope display?

Answer 6

A straight, horizontal line at a level of -70 mV.

This indicates the stable state of the neurone when not firing an action potential.

Question 7

What occurs during an action potential as shown on the oscilloscope?

Answer 7

A spike rising to a maximum voltage of between +30 and +40 mV.

This represents the rapid depolarization of the neurone.

Question 8

What does the rising phase of the spike indicate?

Answer 8

Depolarisation.

This is when the neurone becomes more positively charged.

Question 9

What does the falling phase of the spike indicate?

Answer 9

Repolarisation.

This is when the neurone returns towards its resting potential.

Question 10

What happens just before the membrane rapidly depolarises?

Answer 10

There is a gradual rise in membrane potential.

This phase is often not shown on action potential graphs.

Question 11

What occurs when the threshold potential is reached?

Answer 11

Many more sodium channels open.

This leads to a rapid depolarization of the neurone.

Question 12

What is hyperpolarisation in the context of action potentials?

Answer 12

A short period where the membrane potential becomes more negative than the resting potential.

This typically follows repolarisation and is not immediately corrected.

Question 13

Fill in the blank: The resting potential of a neurone is typically around _______.

Answer 13

-70 mV.

This value is crucial for maintaining the neuron’s readiness to fire an action potential.