Topic 7B - Electrical Activity In The Heart

Front 1

What is the myogenic nature of the heart?

Back 1

The heart is myogenic; it can contract and relax without receiving signals from neurones. This electrical activity in the heart creates the pattern of contractions which coordinates the regular heartbeat.

Front 2

What is an electrocardiograph?

Back 2

1. An electrocardiograph shows how the heart is functioning - it records the electrical activity of the heart.
   
2. Heart muscle depolarises when it contracts and repolarises when it relaxes. An electrocardiograph records these changes in electrical activity using electrodes on the chest.
   

Front 3

What does a normal ECG look like?

Back 3

1. The P wave is caused by atrial systole.
   
2. The main peak (QRS complex) is caused by contraction (depolarisation) of the ventricles.
   
3. The T wave is due to the repolarisation of the ventricles.
   
4. The height of the wave indicates how much electrical charge is passing through the heart.
   
5. A bigger wave means bigger contraction.
   

Front 4

How do doctors use ECGs to diagnose heart problems?

Back 4

Doctors compare patient's ECG with a normal trace. This helps diagnose any problems with the heart's rhythm, which may indicate cardiovascular disease or other heart conditions.

Front 5

What is tachycardia and bradycardia?

Back 5

Tachycardia - the heart beat is too fast.

Around 120 beats per minute. At rest, the heart isn't pumping efficiently.

Bradycardia - heart beats too slow, below 60 bpm at rest.

Front 6

What is an ectopic heartbeat?

Back 6

It is an extra heartbeat caused by an earlier contraction of the atria than the previous heartbeats. It can be caused by early contraction of the ventricles.

Front 7

What is fibrillation?

Back 7

A really irregular heart beat. The atria or ventricles completely lose their rhythm and stop contracting properly. It can result in chest pain, fainting, lack of pulse and death.