Cardiac Cycle PDF | PPT
Human Anatomy and Physiology - 1
Keywords: Cardiac cycle, atrial systole, ventricular systole, ventricular diastole, joint diastole, human anatomy, physiology, PDF notes, PPT slides.
This resource provides comprehensive insights into the cardiac cycle, covering its introduction, key events, and phases such as atrial systole, ventricular systole, ventricular diastole, and joint diastole. Perfect for students and educators in human anatomy and physiology, this material is available in both PDF and PPT formats for easy access and learning.
Cardiac Cycle PDF | PPT
Human Anatomy and Physiology - 1
Introduction
The cardiac cycle refers to the sequence of events that occur during one complete heartbeat, including the contraction (systole) and relaxation (diastole) of the heart chambers. This process ensures the efficient pumping of blood throughout the body, supplying oxygen and nutrients to tissues while removing waste products like carbon dioxide.
Events of the Cardiac Cycle
The cardiac cycle consists of several distinct phases, each playing a crucial role in maintaining circulation. These phases include atrial systole, ventricular systole, ventricular diastole, and joint diastole.
Atrial Systole
Atrial systole marks the beginning of the cardiac cycle. During this phase, the atria contract, pushing blood into the ventricles. This action completes the filling of the ventricles, which were already partially filled during the passive flow of blood from the veins. The atrioventricular (AV) valves remain open during this stage to allow blood to flow freely into the ventricles.
Ventricular Systole
Ventricular systole follows atrial systole. In this phase, the ventricles contract forcefully, increasing the pressure within them. As the pressure rises above that in the atria, the AV valves close to prevent backflow of blood. Subsequently, the semilunar valves open, allowing blood to be ejected into the pulmonary artery (from the right ventricle) and the aorta (from the left ventricle).
Ventricular Diastole
Ventricular diastole occurs when the ventricles relax after contraction. During this phase, the pressure in the ventricles drops below that in the arteries, causing the semilunar valves to close. This prevents blood from flowing back into the ventricles. Simultaneously, the AV valves reopen, allowing blood to flow passively from the atria into the ventricles.
Joint Diastole
Joint diastole represents a brief period during which both the atria and ventricles are relaxed. During this phase, blood flows passively from the veins into the atria and then into the ventricles. This phase sets the stage for the next cardiac cycle by ensuring adequate filling of the ventricles before atrial systole begins again.
Conclusion
Understanding the cardiac cycle is essential for grasping how the heart functions as a pump and maintains systemic circulation. By studying the various phases of the cardiac cycle, learners can gain valuable insights into the intricate mechanisms underlying cardiovascular health and disease. This resource, available in PDF and PPT formats, serves as an excellent tool for academic and professional purposes.
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