Lecture 3

Question 1

What is membrane potential

Answer 1

distribution of ions creating a charge difference

Question 2

what is the charge of a living cell

Answer 2

-70mV

Question 3

What creates membrane potential between ECF and ICF

Answer 3

ECF has high Na+ ions and low K+ ions

ICF has low Na+ ions and high K+ ions

Question 4

What are the chemical gradients

Answer 4

K+ gradient out of the ICF, electrical gradient into ICF

Na+ gradient out of the ICF, electrical gradient into ICF

Question 5

How is information sent down the Axon

Answer 5

as action potentials

-excitation

Question 6

How is an action potential created

Answer 6

When a cell’s resting potential is brought to the threshold through depolarization
this is when voltage-gated sodium channels are activated and rapid depolarization occurs
as Na+ gates close K+ gates open to repolarize to is RMP

Question 7

How does axon propagation occur in unmyelinated axons

Answer 7

1. rapid depolarization at the site of the initial segment (+30mV)
2. Na+ ions enter spreaded away from voltage-gated channel, graded depolarization brings segment 2 membrane to the threshold (-60mV)
3. Action Potential develops in segment 2, (+30mV)
   and initial goes into repolarization
4. Na+ ions entering segment 2, bring segment 3 to the threshold

Question 8

what is graded depolarization

Answer 8

Excitatory/ inhibitory
depolarization - excitatory
hyperpolarization - inhibitory

Question 9

What is the change when axon propagation occurs in myelinated axons

Answer 9

action potentials develop in nodes between Schwann cells

between nodes works as an excellent conductor