Cardiac Cycle Flashcards
What is the correct sequence of flow of an electrical impulse through the heart?
SA node, AV node, AV bundle, Purkinje fibers
The T wave on an ECG is due to?
Ventricular repolarization
The left ventricle refills with blood in preparation for initiation of the next cardiac cycle during ventricular?
Diastole
What is special about the atrioventricular (AV) bundle (bundle of His)
Is the only site where action potentials can conduct from the atria to the ventricles
Ventricular systole is caused by?
Ventricular depolarization
What does SA stand for?
Sino atrial node (SA) NODE
What does AV stand for?
Atrioventricular node (AV) NODE
State what happens to the atria when the impulses spread through them
Atria depolarise and contract (Systole)
State what happens to the ventricles when the impulses spread through them:
Ventricles depolarise and contract (Systole)
When the atrio-ventricular valves shut the ventricles are in what?
Systole
When the semilunar valves shut the ventricles are in what?
Diastole
Describe the electrical events which produce the P wave.
Atria Depolarisation
Name the mechanical cardiac event which accompanies the P wave.
Atrial systole
Describe the electrical events which produce the QRS complex
Depolarization of the ventricles
Name the mechanical cardiac event which accompanies the QRS complex.
Ventricular systole
Describe the electrical events which produce the T wave.
Repolarisation of the ventricles
Name the mechanical cardiac event which accompanies the T wave
Ventricular Diastole
What is the importance of the Sinoatrial (SA) node
The cells of the SA node spontaneously & rhythmically initiate their own depolarisation
It is the hearts pacemaker and determines heart rate.
Explain Ventricular depolarisation
Stimulates the ventricles to contract from the apex
upwards and then the ventricles relax
List some Age related changes to the cardiac cycle
- Blood vessel wall lining (endothelium) becomes thickened - Heart valves (specifically the Aortic valve) become stiffened and thicker. - Progressive degeneration of cardiac structures,
What will affect the cardiac cycle?
- Conduction / Electrical conditions
- Mechanical/ Pump Failure conditions
- Valve problems=blood flow issue (valve stenosis) or an incompetent
valve= increasing cardiac pressure leading to pump failure issues.
Describe two Lethal heart rhythms
- Ventricular tachycardia
- Ventricular fibrillation
What is the role of the cardiac cycle in the medulla oblongata?
To increase or decrease firing of SA node/rate and contractility
The left ventricle refills with blood in preparation for initiation of the next cardiac cycle during ventricular
Diastole
Ventricular systole is caused by?
Ventricular depolarization
During exercise, increased muscle contraction helps return more blood to the heart. This would lead to
Increased stroke volume
What causes atrial systole?
When the electric impulse is initiated it sends a wave of excitation though the atria and this is what causes atrial systole
What causes Ventricular systole
When the electrical impulse reaches the purkinje fibres it conducts the impulse to the ventricles which causes Ventricular systole
On a ECG complex what does the P wave represent?
Atrial Depolarisation
On a ECG complex what does the QRS complex represent?
Ventricular depolarisation
On a ECG complex what does the T wave represent?
Ventricular repolarization
