myelination and saltatory conduction

Question 1

myelin sheat - what is it and what is the function?

Answer 1

• Schwann cells
• electrical insulator, so stops depolarisation
• therefore prevents ions moving in or out of the cell

Question 2

nodes of ranvier - what are they and what is the function?

Answer 2

• gaps between groups of myelin sheath
• have lots of Naᐩ and Kᐩ channels
• only place where depolarisation can occur
• action potentials have to jump there via saltatory conduction

Question 3

saltatory conduction

Answer 3

when an action potential jumps between nodes of ranvier

Question 4

what is the function of saltatory conduction?

Answer 4

• speeds up the transmission of nerve impulses

- cytoplasm will conduct enough charge to depolarise the next node

Question 5

how can the speed of an acton potential be increased?

Answer 5

• increase temperature

- increase the axon diameter

Question 6

increasing temp

Answer 6

• = a faster action potential speed

- because the rate of diffusion increases at higher temperatures

Question 7

increasing the diameter of the axon

Answer 7

• = a fater action potential speed
• because there is greater surface area
• so there is less resistance