PHYSIOLOGY
CARDIOVASCULAR PHYSIOLOGY
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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The left and rigth atria contract
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The left and right ventricles contract
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The atria fill with blood from the superior vena cava
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The tricuspid valve closes
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Detailed explanation-1: -Electrical charges spontaneously pulse from the SA node causing the two atria to contract in unison. The pulse reaches a second node, called the atrioventricular (AV) node, between the right atrium and right ventricle where it pauses for approximately 0.1 second before spreading to the walls of the ventricles.
Detailed explanation-2: -The conduction system of the heart. Normal excitation originates in the sinoatrial (SA) node, then propagates through both atria (internodal tracts shown as dashed lines).
Detailed explanation-3: -The signal travels to the AV node (atrioventricular node). This node is between the atria and the ventricles. In the AV node, the impulses are slowed down for a very short time. This allows the atria to contract a fraction of a second before the ventricles.