factors affecting the speed of an action potential

Question 1

what are the factors that affect the speed of an action potential ?

Answer 1

• myelination and saltatory conduction
• axon diameter
• temperature

Question 2

how is the myelin sheath formed ?

Answer 2

• it is schwann cells which are wrapped around the axon

Question 3

what are the features of the myelin sheath ?

Answer 3

• it is made up of lipids
• so does not allow charged ions to pass through it

Question 4

what are the gaps between the myelin sheath called ?

Answer 4

• nodes of ranvier

Question 5

how do action potentials travel across the axon ?

Answer 5

• action potentials jump from node to node ( saltatory conduction)

Question 6

what is the benefit of saltatory conduction ?

Answer 6

• action potentials are able to travel along the axon faster as it doesnt have to generate an action potential along the whole length, just at the nodes of ranvier
• less ATP is used for the resting potential due to there being less membrane

Question 7

how does axon diameter affect the speed of action potentials ?

Answer 7

• with a wider diameter the speed of conductance increases
• a wider diameter means there is less leakage of ions and therefore action potentials travel faster

Question 8

how does a higher temperature increase the speed of action potentials ?

Answer 8

• the ions diffuse faster ( rate of diffusion increases )
• the enzymes involved in respiration work faster
  so there is more ATP for active transport in the Na+ / k+ ATPase active transport protein