1.5 Control and Regulation of The Cardiac Cycle Flashcards
What is the SA node (sino-atrial node) responsible for?
The SA node passes a wave of electrical current through the atria, making them contract.
What does the AV node (atrial ventricular node) do?
The AV node is a patch of tissue separating the two ventricles that allows the electrical current through. It slows the passage of current down to allow the ventricles to fill with blood.
What do purkyne fibres do?
They carry the electrical current down the middle of the ventricles to the apex of the heart. This allows the bottom of the heart to contract first, resulting in an upwards squeezing action that forces blood out into the arteries.
What can we do to observe the electrical coordination of the cardiac cycle?
An ECG monitor.
How do you set up an ECG monitor?
Electrodes are attached to the chest and fed to a computer linked to a screen or printer.
What does the P wave show?
The P wave shows the moment when both atria are contracting.
What does the QRS wave show?
The QRS wave shows the ventricles contracting (systole).
What does the T wave show?
The T wave shows the ventricle relaxing (diastole).
