(S1W1) Neurophysiology part 3

Question 1

What is an action potential?

Answer 1

• the most important unit of information transmission in the body
• the change in the electrical potential associated with the passage of an impulse along the membrane of a muscle cell or nerve cell
• when the depolarisation of the neuron membrane reaches a critical “threshold” value an action potential is formed

Question 2

Explain resting membrane potential

Answer 2

• At rest your membrane within the neuron has a certain potential (about -70 millivolts)
• You’ve got lots of potassium K+ ions inside the membrane and sodium Na+ outside the membrane
• There’s lots more sodium than there is potassium so more positive outside than inside
• Meaning the inside is more negative (-70 mV)
• Resting membrane potential is maintained through the sodium potassium pump, which uses active control (uses energy)
• Pumps out 3 sodium ions, for every 2 potassium ions that it pumps in

Question 3

What does hyperpolarising mean?

Answer 3

the inside of the membrane is getting more negative (further from 0)

Question 4

What does depolarising mean?

Answer 4

the inside of the membrane getting more positive (closer to 0)

Question 5

Which type of signal increases the chances of an action potential and therefore a muscle contraction?

Answer 5

a depolarising signal

Question 6

A hyperpolarising signal decreases the chances of an action potential and muscle contraction. True or False?

Answer 6

true

Question 7

Give an example of depolarising and hyperpolarising signals

Answer 7

if we have a reflex that stimulates your bicep and tries to turn your triceps off, you get this depolarising signal towards the biceps to increase the chance of a contraction, whereas you get the hyperpolarising signal towards the triceps to decrease the chances of a contraction