it is cool
When relaxed, the atria expand, and then the ventricles contract.
Yes, atria contracts before the ventricles.
After the SA node stimulates the atria to contract, the electrical impulse travels to the atrioventricular (AV) node, where it is briefly delayed. This delay allows the atria to fully contract and push blood into the ventricles. Following this, the impulse proceeds down the bundle of His and into the Purkinje fibers, causing the ventricles to contract and pump blood to the lungs and the rest of the body. This sequence ensures coordinated heartbeats and efficient blood flow.
tricuspid valve
the atriventriculart node causes both atria to contract
The atria contract simultaneously to push blood into the ventricles. This coordinated contraction ensures efficient filling of the ventricles with blood before they contract to pump blood out to the rest of the body.
The blood is squeezed into the ventricles.
The atria.
semilunar valves
They both contract at the same time.
There are no valves between the atria. The valves between the atria and ventricles close when the ventricles contract.
The atria contract during the cardiac cycle's atrial systole phase, which occurs just before the ventricles contract. This contraction helps push blood from the atria into the ventricles, completing the filling of the ventricles before they contract during ventricular systole. Atrial contraction is facilitated by electrical signals from the sinoatrial (SA) node, ensuring synchronized heart function.