Question

Define cardiac cycle and follow the events of one cycle

Answer 1

1 cardiac cycle take time about 0.8 second 
0.2second- atrium contraction
0.4second - ventricle contraction 
0.4 second for total diastole.

Answer 2

Answer:

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♥ ①　　$\rm\underline\red{CARDIAC~~CYCLE~~:-}$

● Cardiac cycle consists of three stages namely $\sf\blue{atrial~systole~, ~ventricular~systole~and~cardiac~diastole}$ .

• Blood enters the atria from pulmonary veins and venacavae.
• From atria blood flows into ventricles through atrioventricular apertures.
• The semilunar valves are closed at this stage .

♥　 (ⓐ) 　$\rm\underline\red{Atrial~~Systole~~:-}$

• The sino node generates action potential ( $\sf\green{electrical~~impulses}$ ) which pass through atrial walls.
• The atria contract forcing blood into ventricle.
• It is the atrial systole .

♥　 (ⓑ)　 $\rm\underline\red{Ventricular~~Systole~~:-}$

• The action potential reaches $\sf\blue{Atrioventriculwr~~node}$ .
• From AV node it passes through bundle of His and purkije fibres .
• The ventricles contract forcing the blood into pulmonary aorta and systemic aorta.
• The bicuspid and tricuspid valves close producing first heart sound ' $\tt\pink{~Lub~}$ ' .

♥ 　 (ⓒ)　 $\rm\underline\red{Cardiac~~Diastole~~:-}$

Ventricles relax

• The semilunar valves closed at a time producing the second heart sound ' $\tt\pink{~Dub~}$ ' .
• As the ventricular pressure decreases further, the AV valves open.
• The cycle of events begin again.
• The duration of cardiac cycle is $\tt\pink{0.8}$ sec .

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