ELM 4.1

Question 1

what relation does the value of lambda have on how far the signal can travel?

Answer 1

the higher the value of lambda, the further the signal can travel before dropping to 37% of its starting value

Question 2

What does the length constant depend on ? (3)

Answer 2

inversely proportional to Rm (the resistance of the insulating material - the higher this is, the less leaky it is) is the leakiness
resistance of conducting material - want it to be as low as possible bc we want high conductivity
diamater

Question 3

Why is attenuation in dendrites not a big problem? (2 reasons)

Answer 3

• short distances involved
• many inputs (big starting signal)

Question 4

Dendritic transmission is always …

Answer 4

passive - does not involve a wave of action potentials

Question 5

what adaptations can nature have to increase transmission speed?

Answer 5

better insulation and fatter cables

Question 6

the nodes of ranvier have a high concentration of what

Answer 6

sodium channels

Question 7

define saltatory conduction

Answer 7

a wave of action potentials interspersed by segments of rapid cable conduction

Question 8

Myelin is provided by a glial cell - what are the different glial cells in the CNS neurons and peripheral neurons

Answer 8

CNS - oligodendrocye
peripheral - Schwann

Question 9

Myelination is a unique feature of what

Answer 9

axons

Question 10

Which parts of a neuron is covered with myelin

Answer 10

Internode

Question 11

In mammalian neurones, the density of Na+ channels in the nodes of Ranvier is approximately:

Answer 11

1200/um^2