4. Action potential

Question 1

What can measure the neuron signalling? (Action potentials psychobiology)

Answer 1

Oscilloscope

Question 2

What is shown through a concentration gradient? (Action potentials psychobiology)

Answer 2

Ions of a higher concentration pulled toward a lower concentration

Question 3

What is shown through an electrical gradient? (Action potentials psychobiology)

Answer 3

Ions of a positive charge are pulled towards those of a negative charge

Question 4

What does the transmembrane voltage force and what will this lead to? (Action potentials psychobiology)

Answer 4

Counterbalance

No net ion flow across the membrane

Question 5

If a cell is permeable to more than one ion, what is the cells potential measured by? (Action potentials psychobiology)

Answer 5

Goldmann-Hodgkin-Katz equation

Question 6

What 4 factors contribute to resting membrane potential? (Action potentials psychobiology)

Answer 6

• Selective permeability
• Potassium gradients
• Sodium gradients
• Ion pumps

Question 7

How does selective permeability affect resting membrane potential? (Action potentials psychobiology)

Answer 7

May be more permeable to potassium ions

Question 8

How does potassium gradients affect resting membrane potential? (Action potentials psychobiology)

Answer 8

In the cell, potassium ion concentration is lower than outside the membrane, so potassium ions are pulled back in

Question 9

How does sodium gradients affect resting membrane potential? (Action potentials psychobiology)

Answer 9

The membrane is slightly permeable to sodium ions which shift the resting potential from -90mV to -70mV

Question 10

How does ion pumps affect resting membrane potential? (Action potentials psychobiology)

Answer 10

Sodium pumps move two potassium ions into the cell for every three sodium ions moved out

Question 11

What is potassium equilibrium potential? (Action potentials psychobiology)

Answer 11

90mV

Question 12

What do ion pumps help to do? (Action potentials psychobiology)

Answer 12

Keep the intracellular potassium concentration high

Question 13

Over time, what would a graph showing membrane potential look like? (Action potentials psychobiology)

Answer 13

resting potential (middle flat line)
depolarisation (rapid climb)
depolarisation (rapid fall)
hyper polarisation (low climbing line)

Question 14

What are the stages of action potentials? (Action potentials psychobiology)

Answer 14

1) Threshold potential reached
2) Depolarisation due to the opening of sodium channels
3) Depolarisation due to inactivation of sodium channels and opening of potassium channels
4) Hyper-polarisation as potassium channels are still open

Question 15

What does action potential create? (Action potentials psychobiology)

Answer 15

A positive feedback

Question 16

What does the absolute refractory period force? (Action potentials psychobiology)

Answer 16

One way transmission

Question 17

What is the absolute refractory period? (Action potentials psychobiology)

Answer 17

Where a second action potential cannot be initiated, no matter how big the applied stimulus is

Question 18

What is the relative refractory period? (Action potentials psychobiology)

Answer 18

The interval, immediately following the ARP, where a second action potential is inhibited but not impossible

Question 19

What is the charging of the membrane known as? (Action potentials psychobiology)

Answer 19

Capacitance

Question 20

How does the thickness of the membrane change the charging of it? (Action potentials psychobiology)

Answer 20

The thicker the membrane, the less capacitance

Question 21

What does myelin do? (Action potentials psychobiology)

Answer 21

Reduces the charge loss across the axon membrane by decreasing its capacitance