8 - ACTION POTENTIALS IN MYELINATED NEURONES Flashcards
Which neurones are said to be myelinated?
The neurones which have a myelin sheath.
What is the myelin sheath?
An electrical insulator
What is made of?
A type of cell called a Schwann cell.
What is between the Schwann cells?
Tiny patches of bare membrane called the node of Ranvier.
What is concentrated at these nodes?
Sodium ion channels.
Where does depolarisation happen in a myelinated neurone?
At the nodes of Ranvier where sodium ions can get through the membrane.
What does the neurone’s cytoplasm do?
It conducts enough electrical charge.
To do what?
to depolarise the next node, so the impulse jumps from node to node, and this process is called salutatory conduction.
How does the impulse travel in a non-myelinated neurone?
As as wave along the whole length of the axon membrane
What does this mean in terms of the salutatory conduction?
It means that it is slower than the myelinated neurones
