Contraction of The Heart

Question 1

What is the sino-atrial node (SAN)

Answer 1

triggers the wave of excitation.

Question 2

What is the atrio ventricular node (AVN)

Answer 2

delays the impulse, transmits it to the bundle of his

Question 3

What is bundle of his

Answer 3

Lots of purkyne fibres that penetrate the septum.

Question 4

What are purkeyne fibres

Answer 4

conductive tissue which carries the impulse.

Question 5

What is the apex

Answer 5

the bottom of the heart.

Question 6

Contraction of the heart 1/4

Answer 6

Wave of excitation begins in the Sino-Atrial node (pacemaker). This causes the atria to contract and initiates the heartbeat.
Insulating tissue stops the wave of excitation being spread immediately to the ventricles.

Question 7

Contraction of the heart 2/4

Answer 7

The WOE triggers the Atrio-Ventricular node (which causes a delay) to transmit the impulse to the bundle of his.

Question 8

Contraction of the heart 3/4

Answer 8

The impulse travels though the septum in the bundle of his, until it splits into two branches of purkyne fibres at the apex.

Question 9

Contraction of the heart 4/4

Answer 9

The purkyne fibres transmit the wave of excitation to the ventricles causing them to contract, starting at the apex.