The Electrical Activity Of The Heart

Question 1

Describe the steps of the electrical activity of the heart

Answer 1

1. The SA node generates impulse; atrial excitation begins
2. Impulse delayed at AV node
3. Impulse passes to the heart apex ; ventricular excitation begins
4. Ventricular excitation complete at the bundle of his or Purkinje fibres

Question 2

What does myogenic mean?

Answer 2

Originating in the cardiac muscle

Question 3

What does systolic phase mean?

Answer 3

The phase in the heart when it contracts.

Question 4

What does diastolic phase mean?

Answer 4

The phase of the heart when it relaxes.

Question 5

What is the average blood pressure?

Answer 5

120/80 mmgh

Question 6

What is the full form of mmgh?

Answer 6

Millimetres of mercury

Question 7

What is the average heart rate?

Answer 7

60- 80 bpm

Question 8

What is the full form of bpm?

Answer 8

Beats per minute

Question 9

What are the 3 electrical wave phases?

Answer 9

P wave, QRs complex, T wave

Question 10

What is p wave?

Answer 10

Atrial contraction / depolarisation

Question 11

What is QRs complex?

Answer 11

Ventricular contraction / depolarisation

Question 12

What is T wave?

Answer 12

Ventricular relaxation / repolarisation

Question 13

Why is ventricular wave larger than atrial wave?

Answer 13

Blood is required to pump further in the ventricles than the atrium so needs a greater excitation.

Question 14

Why is atrial repolarisation not included?

Answer 14

Takes place at the same time that the ventricular depolarisation takes place.