Schwann Cells

Question 1

What is the myelin sheath and what is it made out of?

Answer 1

It is an electrical insulator along most of the axon , preventing any flow of ions across the membrane. It is made up of schwann cells.

Question 2

What are the gaps on the myelin sheath called? What do they do?

Answer 2

Nodes of Ranvier. Sodium channels are connected at the nodes. They’re gaps in the myelin sheath and they’re the only place whether depolarisation can occur.

Question 3

How does the myelin sheath conduct an impulse?

Answer 3

As ions flow across the membrane at one node during depolarisation, a circuit is set up which reduces the potential difference of the membrane at the next node, triggering an AP. Impulse, effectively, jumps from one node to next. This ‘jumping’ conduction is saltatory conduction.

Question 4

What is the benefit of saltatory conduction?

Answer 4

It is much faster than a wave of depolarisation along the whole membrane.