Heart and Cardiac Cycle：練習題

What occurs during the phase of the cardiac cycle known as ventricular diastole?

Which of the following describes the state of the heart valves during the phase of the cardiac cycle when blood is being actively pumped from the left ventricle into the aorta?

Consider a phase in the cardiac cycle where the pressure within the left ventricle has just exceeded the pressure in the left atrium, but remains lower than the pressure in the aorta. What is the status of the bicuspid valve and the aortic semilunar valve during this specific moment?

Which blood vessel is responsible for transporting oxygenated blood from the lungs back to the left atrium of the heart?

During the cardiac cycle, what occurs immediately after the ventricles contract (ventricular systole)?

Define the term cardiac cycle and state the specific phase during which the heart muscle is in a state of relaxation.

During the early phase of ventricular diastole, the pressure in the left atrium becomes higher than the pressure in the left ventricle. Describe the resulting effect on the bicuspid valve and the movement of blood within the heart.

In the provided diagram of the heart, identify the structures labeled and explain what would happen to the flow of blood during ventricular systole if the chordae tendineae attached to the bicuspid valve were to rupture.

The diagram shows a transverse section through the lower part of a human heart, revealing the thickness of the muscular walls of the two ventricles.

(a) Identify which chamber has the thicker muscular wall and explain the physiological importance of this structural difference.
(b) Explain why the blood pressure in the pulmonary artery is significantly lower than the blood pressure in the aorta.

The diagram illustrates the pressure changes in the left atrium, left ventricle, and aorta during one complete cardiac cycle of a healthy adult at rest.

(a) During the period between label Q and label R, the pressure in the left ventricle exceeds the pressure in the aorta. Identify the valve that is open during this phase and explain the physiological significance of the ventricular pressure being higher than the aortic pressure. (2 points)

(b) Based on the graph, the duration of one complete cardiac cycle is exactly \(0.80\text{ s}\). Calculate the heart rate of this individual in beats per minute. (1 point)

(c) Point S indicates the moment when the pressure in the left ventricle falls below the pressure in the left atrium. Name the valve that opens at this specific point and describe the subsequent change in the volume of the left ventricle. (2 points)

(d) In the same individual, the peak pressure reached in the right ventricle is only about \(25\text{ mmHg}\), compared to the \(120\text{ mmHg}\) reached in the left ventricle. Explain how the structure of the heart accounts for this difference and why a lower pressure is necessary for the blood moving from the right ventricle. (2 points)