What is the correct order of the cardiac conduction system?
The cardiac conduction system comprises the following structures, in order, the SA node, the AV node, the bundle of His, the bundle branches, and the Purkinje fibers.
What are the 5 steps of the conduction pathway?
Intrinsic Conduction System of the Heart
- Step 1: Stimulation of the sinoatrial node.
- Step 2: Stimulation of the atrioventricular node.
- Step 3: Propagation to the AV bundle.
- Step 4: Splitting into the bundle branches.
- Step 5: Propagation up the Purkinje fibers (subendocardial conducting network)
Which part of the conduction system Depolarizes the fastest?
the sinus node
Cells within the sinus node have the fastest rate of spontaneous depolarization, and, therefore, the sinus node is the main pacemaker region of the heart. The AV node has the second fastest rate of spontaneous depolarization, which allows it to create an escape rhythm if the sinus node is diseased.
What are the steps of the cardiac cycle?
The cardiac cycle involves four major stages of activity: 1) “Isovolumic relaxation”, 2) Inflow, 3) “Isovolumic contraction”, 4) “Ejection”.
What is heart depolarization?
Depolarization of the heart is the orderly passage of electrical current sequentially through the heart muscle, changing it, cell by cell, from the resting polarized state to the depolarized state until the entire heart is depolarized.
Which fiber system is the first to depolarize in a cardiac cycle *?
A&P 2
| Question | Answer |
|---|---|
| A stethoscope placed at the upper tip of the sternum will be best to detect which sound? | tricupsid valve |
| Which fiber system is the first to depolarize in a cardiac cycle? | sinoatrial (SA) node |
| Which chamber of the heart contains the natural in situ pacemaker? | right atrium |
Does the SA node depolarize first?
The Sinoatrial node (SA) sets the heart rate. It is the “pacemaker” because its fastest ability to auto-depolarize and repolarize makes it the first to initiating each normal heart beat. It is believed that initial SA node action potential propagates from a small group of cells near the center of the SA node.
What are the 4 phases of diastole?
The four components of diastole include (1) isovolumic relaxation period (2) rapid filling (3) slow filling (4) atrial systole. However, factor that influence normal diastolic function also include myocardial relaxation or compliance, elastic recoil, passive ventricular filling, atrial function, and HR [16].
What is the first phase of the cardiac cycle?
The cardiac cycle begins with atrial systole, the sequential activation and contraction of the 2 thin-walled upper chambers. Atrial systole is followed by the delayed contraction of the more powerful lower chambers, termed ventricular systole.
In what layer of the heart does depolarization begin?
The wave of depolarization begins in the right atrium, and the impulse spreads across the superior portions of both atria and then down through the contractile cells. The contractile cells then begin contraction from the superior to the inferior portions of the atria, efficiently pumping blood into the ventricles.
