1.5 Control And Regulation Of The Cardiac Cycle

Question 1

What does the T wave show?

Answer 1

When ventricles are relaxing (diastole)

Question 2

What does the QRS wave show?

Answer 2

Shows the ventricle contracting (systole)

Question 3

What does the P wave show?

Answer 3

The moment when the atria are contracting

Question 4

How does a ECG work?

Answer 4

Electrodes are attached to the chest and led to a computer linked to a screen or printer. Activity of the heart can then be represented as a trace consisting of a number of waves or spikes.

Question 5

What is an ECG short for?

Answer 5

Electrocardiogram

Question 6

What do purkyne fibres do?

Answer 6

Carry the current down the middle of the ventricles to the base or apex of the heart. Allows bottom of heart to contract first, resulting in an upwards squeezing action, forcing the blood out into the arteries.

Question 7

What is the AV node and what does it do?

Answer 7

Atrial ventricular node

Acts like a turnstile at a station, slowing the passage of current down to allow the ventricles to fill with blood.

Question 8

What is the SA node and what does it do?

Answer 8

Sino-atrial node

Passes a wave of electrical current through the atria, making them contract.