Select all that occur during ventricular systole – Ventricular systole, a crucial phase in the cardiac cycle, encompasses a series of intricate events that propel blood from the heart’s ventricles into the systemic circulation. This article delves into the physiological processes that characterize ventricular systole, shedding light on its significance in maintaining cardiovascular health.
Ventricular systole initiates with isovolumetric contraction, followed by ventricular ejection, isovolumetric relaxation, and ventricular filling. Each phase is orchestrated by a symphony of valvular actions and hemodynamic changes, ensuring efficient blood flow and cardiac output.
Ventricular Systole: Select All That Occur During Ventricular Systole
Ventricular systole is the phase of the cardiac cycle in which the ventricles contract and pump blood out of the heart. It begins with the electrical depolarization of the ventricles and ends with the repolarization of the ventricles. Ventricular systole is divided into three phases: isovolumetric contraction, ventricular ejection, and isovolumetric relaxation.
Isovolumetric Contraction
Isovolumetric contraction is the first phase of ventricular systole. It begins with the electrical depolarization of the ventricles and ends when the aortic and pulmonary valves open. During isovolumetric contraction, the ventricles contract but the volume of blood within the ventricles does not change.
This is because the atrioventricular valves are closed and the aortic and pulmonary valves are closed. The pressure within the ventricles increases during isovolumetric contraction.
Ventricular Ejection
Ventricular ejection is the second phase of ventricular systole. It begins when the aortic and pulmonary valves open and ends when the aortic and pulmonary valves close. During ventricular ejection, the ventricles contract and the volume of blood within the ventricles decreases.
This is because the blood is ejected out of the ventricles and into the aorta and pulmonary artery. The pressure within the ventricles decreases during ventricular ejection.
Isovolumetric Relaxation
Isovolumetric relaxation is the third phase of ventricular systole. It begins when the aortic and pulmonary valves close and ends when the atrioventricular valves open. During isovolumetric relaxation, the ventricles relax but the volume of blood within the ventricles does not change.
This is because the atrioventricular valves are closed and the aortic and pulmonary valves are closed. The pressure within the ventricles decreases during isovolumetric relaxation.
Ventricular Filling, Select all that occur during ventricular systole
Ventricular filling is the phase of the cardiac cycle in which the ventricles fill with blood. It begins when the atrioventricular valves open and ends when the atrioventricular valves close. During ventricular filling, the ventricles relax and the volume of blood within the ventricles increases.
This is because the blood flows into the ventricles from the atria. The pressure within the ventricles decreases during ventricular filling.
Quick FAQs
What is the significance of isovolumetric contraction in ventricular systole?
Isovolumetric contraction generates pressure within the ventricles, enabling them to overcome the resistance of the semilunar valves and initiate blood ejection.
How does ventricular ejection contribute to cardiac output?
Ventricular ejection is the primary mechanism by which blood is propelled from the ventricles into the systemic circulation, directly influencing cardiac output.
What factors contribute to ventricular filling?
Ventricular filling is influenced by factors such as atrial pressure, ventricular compliance, and the pressure gradient between the atria and ventricles.
