Electricity in the body

Question 1

What is an action potential?

Answer 1

Short lived electrical charge which travels down an axon (moving depolarisation)

Question 2

Define Resting membrane potential

Answer 2

When there is a difference in the electrical charge across a cell’s membrane.

The outside of the cell is more positively charged compared to the inside of the cell.

Question 3

Electricity: Define depolarisation

Answer 3

When the charges in resting membrane potential are ‘reversed’ - the inside of the cell becomes more negative and the outside of the cell becomes more positive, relative to each other.

Usually occurs due to Na+ flooding into the cell (bringing positive charge)

Question 4

Define repolarisation

Answer 4

Repolarisation is when the cell returns to its usual polarised state, ie the outside of the cell is more positive than the inside of the cell.

Usually occurs when K+ leaves cell.

Question 5

What is the primary pacemaker of the heart?

Answer 5

Sinoatrial node

Question 6

What does the P wave represent?

Answer 6

P wave represents the depolarisation of the atria

Question 7

What does the Q wave represent?

Answer 7

Q wave represents the beginning of ventricular depolarisation

Question 8

What does the R wave represent?

Answer 8

R wave represent the spreading of excitation of right and left ventricular myocardium

Question 9

What does the S wave represent?

Answer 9

S wave represents the completion of ventricular depolarisation

Question 10

What does the T wave represent?

Answer 10

T wave represents the rapid late repolarisation of the ventricular myocardium