Action Potential

Question 1

What forms nerves

Answer 1

Bundles of axons

Question 2

What are the longest nerve axons in the human body

Answer 2

Sciatic nerve axons

Question 3

Which type of nerve axons are in the peripheral nervous system

Answer 3

Schwann cells

Question 4

Which type of nerve axons are in the central nervous system

Answer 4

Oligodendrocytes

Question 5

What does the resting membrane potential rely on

Answer 5

The concentration gradient of potassium ions as the membrane is most permeable to these ions

Question 6

In neurons what is the resting potential value

Answer 6

Around - 70 mV

Question 7

What do all cells have in relation to potentials

Answer 7

They all have a resting membrane potential

Question 8

What generates a negative charge in the cell membrane when potassium moves down the concentration gradient and out

Answer 8

Anions are left behind to create this negative charge

Question 9

When does potassium stop moving out of the cell membrane during resting potential

Answer 9

Until the electrical attraction is as strong as the concentration gradient

Question 10

What maintains the gradient of the ions within the resting potential

Answer 10

The sodium potassium pump which uses ATP

Question 11

When is the action potential started

Answer 11

When the axon hillock is depolarised

Question 12

What is depolarised in action potential

Answer 12

Is the increase in the voltage

Question 13

Why does depolarisation in action potential normally happen

Answer 13

Due to an influx of sodium from synapse or receptor binding

Question 14

What must happen to produce and action potential

Answer 14

The voltage must exceed threshold voltage (-55)

Question 15

What is moving into the cell during action potential

Answer 15

Sodium which is positive therefore increase on the graph during depolarisation

Question 16

How does depolarisation increase

Answer 16

Through the opening of more and more voltage sensitive sodium channels

Question 17

What is the maximum peak voltage of an action potential

Answer 17

+40 mV

Question 18

What does the high voltage of action potential lead to

Answer 18

Closing of the sodium channels and opening of the potassium channels

Question 19

What happens during repolarisation

Answer 19

Sodium is stop at coming into the cell and potassium starts moving out reducing the positive charge within the cell as there is more potassium in the cell

Question 20

What is the refractory period

Answer 20

After the action potential there is too little potassium within the cells therefore an even lower voltage then resting rate occurs then potassium rate gradually returns to resting state

Question 21

At what state can the action potential not occur to the axon

Answer 21

During the refractory period

Question 22

What does depolarisation of the axon membrane lead to

Answer 22

Depolarisation of adjacent sections of the membrane if the threshold voltage is reached - the signal is propagated and moves along the neuron

Question 23

What does myelination increase

Answer 23

Speed and efficiency of action potentials

Question 24

What is myelin made of

Answer 24

Lipid rich substance not permeable to ions like an insulation wire

Question 25

What are the nodes of ravier

Answer 25

The gaps between myelin on the axon and the only areas of membrane which can be depolarised

Question 26

What is saltatory conduction

Answer 26

It allows action potentials to appear to hop along from gap to gap in the myelination

Question 27

What does myelination reduce

Answer 27

The degradation of the action potential over the length of the axon

Question 28

What happens during multiple sclerosis

Answer 28

Myelin is damaged and destroyed over time