3.1.2: Cardiac Cycle

Question 1

What is the function of the Bundle of His in the heart?

Answer 1

Conducts and transmits the wave of depolarisation from the AVN down the septum and Purkyne fibres

The Bundle of His is crucial for coordinating the contraction of the ventricles in the heart.

Question 2

What prevents the wave of depolarisation from travelling directly to the ventricles?

Answer 2

A non-conductive layer between the atria and ventricles

This layer acts as an insulator to ensure proper timing in heart contractions.

Question 3

What is the role of the AVN in the heart’s electrical conduction system?

Answer 3

Releases a wave of depolarisation after receiving the first wave

The AVN (Atrioventricular Node) is responsible for delaying the electrical signal to allow atrial contraction before ventricular contraction.

Question 4

What happens during the contraction of the apex in the heart?

Answer 4

Muscles in the apex contract first, followed by the walls of the ventricles

This sequence ensures efficient blood pumping from the heart.

Question 5

What does an Electrocardiogram (ECG) measure?

Answer 5

Differences in electrical activity in the skin caused by the heart’s electrical activity

Electrodes detect these differences to help diagnose heart rhythm irregularities.

Question 6

What is tachycardia?

Answer 6

When the heart is beating at over 100 bpm

While normal during exercise, it is considered abnormally fast at rest.

Question 7

What is bradycardia?

Answer 7

When the heart is beating at less than 60 bpm

Often seen in athletes due to their high level of fitness, but can be dangerous if too low.

Question 8

What is fibrillation?

Answer 8

An irregular rhythm of the heart

Fibrillation can lead to serious heart complications if not treated.

Question 9

What is an ectopic heartbeat?

Answer 9

Additional heartbeats that are not in rhythm

Commonly occurs once a day, but frequent occurrences may indicate a health issue.

Question 10

Fill in the blank: The _______ is responsible for conducting the wave of depolarisation down to the ventricles.

Answer 10

Bundle of His

Question 11

What is the purpose of the short delay between atrial and ventricular contractions?

Answer 11

Allows enough time for the atria to pump all the blood into the ventricles

This delay is essential for efficient heart function and blood flow.

Question 12

List the main components of an ECG wave.

Answer 12

• P Wave
• QRS Complex
• T Wave
• U Wave
• PR Interval
• QT Interval

Each component corresponds to different electrical activities during the heart’s cycle.