Week 8- The Heart Flashcards
Where is the SAN found?
Medial to the opening of the superior vena cava
Where is the AVN found?
Medial to the right atrio ventricular valve
What is found at the distal end of the AVN
The bundle of His
What does the bundle of His split into?
The left and right bundle branches
What is found at the terminal ends of the right and left bundle branches?
Purkinje fibres
Where are the Purkinje fibres found?
On the endothelial surface of the heart
Which cardiac cells generate action potentials faster than other cardiac cells?
Cells of the SAN
Which cardiac cells generate action potentials slower than other cardiac cells? Describe how this occurs and why?
Cells of the AVN- action potentials take a long time to travel to the distal end of the AVN to allow atrial contraction to finish before ventricular contraction is triggered
What does an ECG measure?
The collective electrical activity of the heart
How is a wave of depolarisation moving towards a lead represented on an ECG?
Positive deflection
What is represented by a horizontal segment on an ECG
A wave of depolarisation at right angles to the lead
How are waves of repolarisation represented on an ECG?
Produce waves opposite to depolarisation eg a wave of repolarisation moving away from a positive lead produces a positive wave
