Coordination of the cardiac cycle

What system controls the heart rate ?

Autonomic nervous system

What does the autonomic nervous system do ?

self governing , control involuntary ( subconscious) activities of internal muscles and glands

Cardiac muscle

Myogenic : self contracting , generates its won electrical impulses

Contraction is caused by electrical impulses, traveling across the muscle

Atrial muscle contacts at a higher or lower frequency then ventricular muscle ?

Slightly higher ( more often )

What is fibrillation ?

Due to the muscle is myogenic, if it is to carefully coordinated it could lead to fibrillation

What are the cells that generates electrical impulses ?

Dino atrial node ( SAN ) - pacemaker cells

Generates electrical impulses, controls frequency of heartbeat

What is the other phase for electrical impulse ?

Wave of excitation

How does the electrical impulse travel through the heart ?

1) SAN sends impulse over atrial muscle as ‘ wave of excitation ‘

2) Atrioventricular septum is non - conductive , it prevents the impulse from traveling down over the ventricle walls.

3) The impulse pauses at the AVN, allowing time for the atria to fully contract and empty the blood into the ventricles , before the ventricles contracts.

4) Impulse travel down bundle of his the though purkinje fibers over ventricle muscle

What is a ECG ?

Electrocardiogram

What are the uses of ECG ?

Shows the electrical activity of the heart during one cardiac cycle

Draw a graph of one heartbeat ?

What does P mean ?

Excitation of atria

What does QRS mean ?

Excitation of ventricle

What does T mean ?

Diastole

What does this trace show ?

Normal trace , sinus rhythm

What does this trace show ?

Bradycardia, slow heart rate

What does this trace show ?

fast Heart rate , Tachycardia

What does this trace show ?

Atrial Fibrillation

What does this trace show ?

Ectopic heartbeat , single heartbeat is out of rhythm