Biology: Action potential

Question 1

What does binary mean interms of nervous systems?

Question 2

How does neuronal signalling occur?

Question 3

Define neuronal firing

Question 4

Describe VGIC (voltage-gated ion channel) structure

Question 5

What initiates an action potential along a neuron?

Question 6

How is reaching threshold achieved in initiating AP?

Question 7

Draw the stages of an action potential

Question 8

What are graded responses?

Question 9

What happens when the sum of action potentials reach threshold level of depolarisation?

Question 10

Why are action potentials short-lived?

Question 11

What does it mean by action potentials are normally ‘all or nothing’?

Question 12

Ion Movements

• How can we monitor/follow ion movements in single axons during AP?
• What do we rely on when reversing AP?
• What matters when monitoring AP?

Question 13

When can 2nd AP be generated?

Question 14

Why is there a refractory period?

Answer 14

Due to VGSC inactivation

Question 15

Do AP summate?

Question 16

What is Ouabain?

Answer 16

N+K+/ATPase inhibitor

Decreases ATP size progressively until Na+ gradient is reduced to where APs can be initiated

Question 17

What is Tetrodotoxin?

Answer 17

Blocks neuronal VGSC

Abolishes AP

Question 18

Name 2 pharmacological tools/drugs which affect AP

Question 19

How does AP encode information?

Answer 19

Frequency; not amplitude

Question 20

How does depolarisation occur along axon?

Question 21

What regulates speed of conductance?

Question 22

What has a higher storage capacity?

Answer 22

Membranes compared to cytosol

Therefore a fatter axon = decreased longitudinal resistance = faster conductance

Question 23

What is the difference between schwann cells + oligodendrocytes?

Question 24

Describe saltatory conduction

Question 25

What metabolises esters + amides?

Question 26

Are local anaesthetics weak acids or bases?

Question 27

Define pKa

Question 28

Function of local anaesthetics

Question 29

What happens to local anaesthetics @ pH 7.4?

Question 30

Drugs must enter cell in order to work (passing cell membrane) What type of drugs can do this easily + give example

Answer 30

Unionised drugs can pass easily The drug is more unionised + will reach target site quicker Lidocaine has faster onset than bupivacaine Ionised drug binds + blocks VGSC

Question 31

What type of drug cannot easily pass back through membrane?

Answer 31

Ionised drugs

Question 32

What type of drug binds and blocks VGSC?

Question 33

What type of axons can local anaesthetics penetrate?

Question 34

Which fibres carry pain signals?

Question 35

List applications of local anaesthetics