
Define the cardiac cycle. Describe various events of the cardiac cycle.
Answer
492.6k+ views
2 likes
Hint: Cardiac cycle is the rhythmic and cyclic series of electrical and mechanical events, taking place during a heartbeat.
Complete answer:
It consists of two major sets of events, namely auricular events and ventricular events. These are completed in four stages, namely auricular systole, auricular diastole, ventricular systole, and ventricular diastole. The short interval between the end of one cycle and the beginning of the next is called the refractory period. In a healthy individual, the average rate of heartbeat is 72 times per minute. Then, the duration of the cardiac cycle is . The duration of the cardiac cycle is inversely proportional to the rate of heartbeat. The stages of the cardiac cycle can be roughly divided into four stages: The filling phase, Isovolumetric contraction, building up pressure ready to pump blood into the aorta or pulmonary trunk.
During the filling phase, the ventricles are filled with blood in two stages – diastole (heart relaxation) and atrial systole. The stage of Isovolumetric contraction lasts for approximately 50ms while the pressure builds. During the outflow phase the pressure in the ventricles exceeds the pressure in the aorta or pulmonary trunk, the outflow valves open. Blood is pumped from the heart into the great arteries. At the end of the outflow phase, both sets of valves are closed once again. The ventricles begin to relax, reducing the pressure in the ventricles so that the atrioventricular valves open. The ventricles then begin to fill with blood and the cycle begins once again
Additional Information:
- In diastole, both the atria and the ventricles are relaxed. Blood flows from the vena cava and pulmonary veins into the right and left atria respectively, before flowing directly into the ventricles.
- As contraction begins both sets of valves are closed, meaning that no blood can escape from the ventricles. The start of systole therefore massively increases the pressure within the ventricles, ready to eject blood into the aorta and pulmonary trunk.
Note:
- Human heart is a central muscular pressure pump, concerned with the collection, storage, and pumping of blood.
- It’s rhythmic beating keeps the blood in constant circulation. The human heart is a tetralocular or four-chambered organ, with two upper and two lower chambers.
- It’s upper chambers are called auricles of the atria, and the lower ones are called ventricles.
Complete answer:
It consists of two major sets of events, namely auricular events and ventricular events. These are completed in four stages, namely auricular systole, auricular diastole, ventricular systole, and ventricular diastole. The short interval between the end of one cycle and the beginning of the next is called the refractory period. In a healthy individual, the average rate of heartbeat is 72 times per minute. Then, the duration of the cardiac cycle is

During the filling phase, the ventricles are filled with blood in two stages – diastole (heart relaxation) and atrial systole. The stage of Isovolumetric contraction lasts for approximately 50ms while the pressure builds. During the outflow phase the pressure in the ventricles exceeds the pressure in the aorta or pulmonary trunk, the outflow valves open. Blood is pumped from the heart into the great arteries. At the end of the outflow phase, both sets of valves are closed once again. The ventricles begin to relax, reducing the pressure in the ventricles so that the atrioventricular valves open. The ventricles then begin to fill with blood and the cycle begins once again
Additional Information:
- In diastole, both the atria and the ventricles are relaxed. Blood flows from the vena cava and pulmonary veins into the right and left atria respectively, before flowing directly into the ventricles.
- As contraction begins both sets of valves are closed, meaning that no blood can escape from the ventricles. The start of systole therefore massively increases the pressure within the ventricles, ready to eject blood into the aorta and pulmonary trunk.
Note:
- Human heart is a central muscular pressure pump, concerned with the collection, storage, and pumping of blood.
- It’s rhythmic beating keeps the blood in constant circulation. The human heart is a tetralocular or four-chambered organ, with two upper and two lower chambers.
- It’s upper chambers are called auricles of the atria, and the lower ones are called ventricles.
Latest Vedantu courses for you
Grade 11 Science PCM | CBSE | SCHOOL | English
CBSE (2025-26)
School Full course for CBSE students
₹41,848 per year
EMI starts from ₹3,487.34 per month
Recently Updated Pages
Master Class 11 Physics: Engaging Questions & Answers for Success

Master Class 11 Chemistry: Engaging Questions & Answers for Success

Master Class 11 Biology: Engaging Questions & Answers for Success

Class 11 Question and Answer - Your Ultimate Solutions Guide

Master Class 11 Business Studies: Engaging Questions & Answers for Success

Master Class 11 Computer Science: Engaging Questions & Answers for Success

Trending doubts
Explain why it is said like that Mock drill is use class 11 social science CBSE

The non protein part of an enzyme is a A Prosthetic class 11 biology CBSE

Which of the following blood vessels in the circulatory class 11 biology CBSE

What is a zygomorphic flower Give example class 11 biology CBSE

The deoxygenated blood from the hind limbs of the frog class 11 biology CBSE

What is the function of copulatory pads in the forelimbs class 11 biology CBSE
