Question

Define cardiac cycle and explain.

Answer 1

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$\huge\bold\red{ANSWERE}$

$\huge\bold\pink{Cardiac \:Cycle}$

The cardiac cycle is the series of electrical impulses and muscle contractions that pressurizes different chambers of the heart, causing blood to flood in one direction. The cardiac cycle varies in different organisms, due to changes in the structure of the heart. Some organisms have a three-chambered heart, which consists of the sinus venosus, atrium, and ventricle. Most tetrapods have developed a more efficient heart, which can supply a greater pressure of blood to the organisms. The “four-chambered heart”, is actually just a modification of the three chambered heart. The sinus venosus is reduced to the sinoatrial node, located on the right atrium. The atrium and ventricles are divided in the four-chambered heart, allowing a separate pathway to be established to the lungs, allowing for greater oxygenation of the blood. The separate circulations pathways are known as pulmonary (lungs) and systemic (body) circulation.

The following cardiac cycle phases are representative of the mammalian, four-chambered heart. The cardiac cycle of animals with three-chambered hearts is similar, except the atria and ventricles are not divided completely, if at all. In most animals, the heartbeat is regulated by nerves in the sinoatrial node, and carried out by nerves throughout the heart. Heart muscles cells are also connected laterally, allowing them to pass the nerve impulse received to all their neighbors, creating rhythmic contractions. Hagfish, and other organisms that have a more ancestral heart, simply use the heart to move liquid through their body at a slow rate. In organisms such as this, the cardiac cycle is much less distinguished because the heart does not set up a specific rhythm.

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Answer 2

cardiac cycle long lasts for 0.8secs

1) the process when whole heart is at rest and the blood from Vena cavas and pulmonary vein enter both attrium and ventricle.

2) the process when both atrium contract blood flow to ventricles increases and pressure develops which closes valves and causes sound lubb.

3) development of high pressure causes opening of pulmonary and aorta valves so blood moves to lungs and body and due to decrease of pressure they close causing dubb sound.

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