Neural signalling - nerve conduction velocity

Question 1

What is saltatory conduction?

Answer 1

The process by which action potentials ‘jump’ from one node of Ranvier to the next along a myelinated axon

This increases the speed of impulse transmission significantly.

Question 2

What role does myelin play in saltatory conduction?

Answer 2

Myelin insulates the axon membrane, increasing the speed of action potential travel

Myelin is formed from Schwann cells.

Question 3

What prevents depolarisation along sections of the axon covered by myelin?

Answer 3

The myelin sheath stops the diffusion of sodium ions and potassium ions

This is crucial for the rapid transmission of nerve impulses.

Question 4

What are the nodes of Ranvier?

Answer 4

Small, uninsulated sections of the axon that contain clusters of ion pumps and channels

These nodes allow action potentials to occur.

Question 5

How do action potentials propagate in a myelinated axon?

Answer 5

They propagate by jumping from one node of Ranvier to the next

This mechanism is called saltatory conduction.

Question 6

What is the effect of saltatory conduction on impulse speed?

Answer 6

It allows the impulse to travel up to 50 times faster than in an unmyelinated axon of the same diameter

This significantly enhances the efficiency of nerve signal transmission.

Question 7

Fill in the blank: The myelin sheath is formed from _______.

Answer 7

Schwann cells

Question 8

True or False: Saltatory conduction occurs in unmyelinated axons.

Answer 8

False

Saltatory conduction specifically refers to the jumping of action potentials in myelinated axons.

Question 9

What do local circuits of current between the nodes of Ranvier trigger?

Answer 9

They trigger depolarisation in the next section of the axon membrane

This is essential for the continuation of the action potential.