Question

Describe the pressure changes in the atria and ventricles during a cardiac cycle

Answer 1

The cardiac cycle consists of pressure changes that allow blood flow through the heart during diastole and systole. Atrial systole increases pressure to complete ventricular filling, followed by ventricular systole leading to blood ejection into arteries.

Step-by-step explanation:

Pressure Changes During the Cardiac Cycle

The cardiac cycle is a complex series of pressure changes that control the flow of blood through the heart. During diastole, both the atria and ventricles are relaxed, allowing blood to flow into the atria from the veins, which are higher in pressure, and then passively into the ventricles. The atrioventricular valves are open, and the semilunar valves are closed at this time.

As atrial systole begins, the atria contract following an electrical impulse corresponding to the P wave on the ECG, which leads to an increase in atrial pressure, pushing blood into the ventricles. This phase contributes the final 20-30 percent of ventricular filling, known as the "atrial kick", and concludes just before ventricular systole begins.

During ventricular systole, the ventricles contract, increasing the pressure inside them, and pump blood into the pulmonary artery and aorta. The atrioventricular valves close to prevent backflow, while the semilunar valves open to allow blood to leave the heart.

Answer 2

It is a cycle of contraction and relaxation of atria and ventricles.

Step-by-step explanation:

The cardiac cycle is the sequence of electrical, mechanical, sound and pressure events, related to the flow of blood through the cardiac cavities, the contraction and relaxation of each of them (atria and ventricles), the closure and opening of Valves and noise production. This process takes place in less than a second. The reciprocal of the duration of a cycle is the heart rate (as usually expressed in beats per minute, multiply by 60 if the duration is measured in minutes).