The atrial depolarization spreads to the atrioventricular (AV) node, passes through the bundle of His
What is the order of the conduction system of the heart?
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 is the correct order of depolarization in the heart quizlet?
Atrial depolarization, initiated by the SA node, causes the P wave . With atrial depolarization complete, the impulse is delayed at the AV node. Ventricular depolarization begins at apex, causing the QRS complex. Atrial repolarization occurs.
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.
What is the first part of the ventricles to depolarize?
The septum is the first part of the ventricles to be stimulated. Furthermore, the left side of the septum is stimulated first (by a branch of the left bundle of His). Thus, depolarization spreads from the left ventricle to the right across the septum.
What is the correct order the pathway that the excitation moves throughout the heart?
The electrical impulse travels from the sinus node to the atrioventricular node (also called AV node). There, impulses are slowed down for a very short period, then continue down the conduction pathway via the bundle of His into the ventricles.
Which statement is correct concerning the heart?
Answer: The left ventricle pumps oxygenated blood to different body parts , while right ventricle pumps de-oxygenated blood to lungs. The heart is the main pumping organ of the body . Any problems in blood movement will impact the heart.
What are the 4 phases of cardiac cycle?
The cardiac cycle involves four major stages of activity: 1) “Isovolumic relaxation”, 2) Inflow, 3) “Isovolumic contraction”, 4) “Ejection”.
What are the 8 elements of the cardiac conduction system?
- The sino-atrial (SA) node.
- The atrio-ventricular (AV) node.
- The bundle of His.
- The left and right bundle branches.
- The Purkinje fibres.
How the heart contracts step by step?
- The SA node (called the pacemaker of the heart) sends out an electrical impulse.
- The upper heart chambers (atria) contract.
- The AV node sends an impulse into the ventricles.
- The lower heart chambers (ventricles) contract or pump.
Is depolarization the same as systole?
The P wave represents depolarization of the atria and is followed by atrial contraction (systole). Atrial systole extends until the QRS complex, at which point, the atria relax. The QRS complex represents depolarization of the ventricles and is followed by ventricular contraction.
What are the 3 layers of the heart?
The wall of the heart separates into the following layers: epicardium, myocardium, and endocardium . These three layers of the heart are embryologically equivalent to the three layers of blood vessels: tunica adventitia, tunica media, and tunica intima, respectively.
What are the 7 phases of cardiac cycle?
Phase 1 – Atrial Contraction . Phase 2 – Isovolumetric Contraction . Phase 3 – Rapid Ejection . Phase 4 – Reduced Ejection .
Why is V1 and V2 negative in ECG?
In right chest leads V1 and V2, the QRS complexes are predominantly negative with small R waves and relatively deep S waves because the more muscular left ventricle produces depolarization current flowing away from these leads .
Does depolarization mean contraction?
Depolarization does not mean contraction . Depolarization is a process where a cell’s membrane potential becomes more positive.
What’s depolarization of the heart?
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. What is meant by repolarization of the heart muscle?
