Action Potentials

Question 1

What is an action potential?

Answer 1

An electrical signal that travels along a nerve cell - its how neurons send messages.

Question 2

How is an action potential triggered?

Answer 2

From an exchange of ions across the neuron membrane when an ion sends/conducts a signal

Question 3

What are the terms to describe the chemical composition during an action potential?

Answer 3

Polarised: cell is negatively charged compared to outside surroundings (more potassium inside, more sodium outside
Depolarised: cell is LESS polarised than its surroundings (sodium rushing in = positive) the difference in the electrical potential inside and outside is lessening

Question 4

What is a resting membrane potential?

Answer 4

It is the difference in chemical composition inside and outside the cell which causes it to be at rest, its polarized

Question 5

What acronym can be used for the process of an action potential?

Answer 5

RARE - resting, all or nothing, repolarization, end/hyperpolarisation

Question 6

What is first stage during an action potential?

Answer 6

R = Resting → Neuron is ready, but not firing (-70 mV)

Question 7

What is second stage during an action potential?

Answer 7

A = All-or-Nothing/Depolarization → sodium flood in (inside becomes positive) and threshold has to reach -55mV to fire an action potential

Question 8

What is third stage during an action potential?

Answer 8

R = Repolarization → when membrane potential reaches around +30mV sodium gates inactivated and potassium leaves = inside returns to more negative

Question 9

What is fourth stage during an action potential?

Answer 9

E = End / Hyperpolarisation → Briefly more negative than resting, then once potassium gates close it will reset

Question 10

What is the speed of propagation of the action potential?

Answer 10

How quickly the message (action potential) travels through the nerve. Speed can be changed to induce signals where the bigger the axon = faster it travels