CARDIAC CYCLE CLASS 11| BODY FLUIDS AND CIRCULATION | ATRIAL AND VENTRICULAR SYSTOLE AND DIASTOLE

Summary

In this educational session, Bharati, a cardiac educator, explains the process of a cardiac cycle in just 5 minutes. She discusses the systolic and diastolic phases, detailing the contraction and relaxation within the heart's chambers. Bharati describes the sequence from atrial systole, which lasts 0.1 seconds, to ventricular systole and the subsequent sounds heard in a heart examination, like 'lub' and 'dup.' She also covers the atrial and ventricular diastole, emphasizing the importance of understanding these phases for medical professionals.

Takeaways

• 🕒 The heart completes a cardiac cycle in 0.8 seconds, which is 72 times per minute.
• 📏 The terms 'systole' and 'diastole' are used to describe the contraction and relaxation phases of the heart chambers.
• 🔍 'Atrial systole' refers to the contraction of the atria and lasts for 0.1 seconds.
• 🚪 The opening of the AV valves allows blood to flow from the atria to the ventricles during atrial systole.
• 🌊 'Ventricular systole' is when the ventricles contract, and it lasts for 0.3 seconds.
• 🔊 The first heart sound, known as 'lub,' occurs when the AV valves close during ventricular systole.
• 🔄 'Isovolumetric relaxation' happens briefly after the AV valves close and before the semilunar valves open.
• 🌀 'Atrial diastole' is the relaxation phase of the atria, which lasts for 0.7 seconds.
• 🕰 'Ventricular diastole' is the relaxation phase of the ventricles, lasting for 0.5 seconds.
• 🔁 The cardiac cycle is a continuous process that involves the coordinated contraction and relaxation of the heart's chambers to pump blood effectively.

Q & A

What is a cardiac cycle?

A cardiac cycle is the period from the beginning of one heartbeat to the beginning of the next, during which the heart goes through a complete sequence of contractions and relaxations.

How many times does a cardiac cycle occur in a minute?

The script mentions that a cardiac cycle occurs 72 times per minute.

What is the duration of one cardiac cycle in seconds?

According to the script, one cardiac cycle lasts approximately 0.8 seconds.

What are the two terms used to describe the contraction and relaxation of the heart?

The two terms used are 'systole' for contraction and 'diastole' for relaxation.

What happens during the atrial systole?

During atrial systole, which lasts for 0.1 seconds, the atria contract, causing the AV valves to open and blood to flow from the atria into the ventricles.

What is the first sound heard in the heart, and what is it called?

The first sound heard in the heart is called 'lub,' which occurs when the AV valves close.

What is ventricular systole, and what happens during this phase?

Ventricular systole is when the ventricles contract, pushing blood into the aorta and pulmonary artery. During this phase, the heart's first sound, 'lub,' is heard, and the AV valves close, creating an isovolumetric contraction.

What are the semi-lunar valves, and when do they open?

The semi-lunar valves are the aortic and pulmonary valves. They open after the ventricular systole is complete, allowing blood to flow from the ventricles into the aorta and pulmonary artery.

What is the duration of the joint diastole?

The joint diastole lasts for 0.4 seconds, during which both the atria and ventricles are in a relaxed state.

How long does atrial diastole last?

Atrial diastole lasts for 0.7 seconds, which is the majority of the time when the atria are in a relaxed state.

What is the duration of ventricular diastole?

Ventricular diastole lasts for 0.5 seconds, which is when the ventricles are in a relaxed state and filling with blood.

What is the significance of understanding the different phases of the cardiac cycle?

Understanding the different phases of the cardiac cycle is important for diagnosing and treating various heart conditions, as well as for comprehending the heart's function in health and disease.