Step by step, please describe the pressure changes that occur in the ventricles

Question

Step by step, please describe the pressure changes that occur in the ventricles during the cardiac cycle. How do the pressure changes relate to the occurence of the heart sounds? This question is paraphrased from my physiology textbook, Human Physiology, 14th ed. Step by step, please describe the pressure changes that occur in the ventricles during the cardiac cycle. How do the pressure changes relate to the occurence of the heart sounds? This question is paraphrased from my physiology textbook, Human Physiology, 14th ed.

Explanation / Answer

when the heart is in diastole , pressure in systemic arteries is about 80mm Hg

1. as the ventricle begins contraction, intraventricular pressure rises. atriventricular value closed which doesnt allow blood to enter or eject from the ventricles. this is phase called isovolumetric contraction.

2. when the pressure of left ventricle becomes greater than aorta then phase of ejection starts since semilunar valves open. pressure rises upto 120 mm Hg

3. semilunar valves close as the pressure of ventricles fall below the pressure of aorta. pressure of left ventricle falls to 0 mm HG whereas pressure of aorta falls down 80mm Hg.

4. AV and semilunar valves closed till the pressure of ventricles fall below the pressure of artia. this phase is isovolumetric relaxatiion.

5. as the pressure falls, rapid filing of ventricles occur through AV valve.

6. atrial contraction empties the whole volume into the ventricles for next ventricular contraction.

same events occur in right ventricle and pulmonary circulation but pressure is lower. max pressure during systole is 25mm Hg which falls upto 8mm Hg.

heart sounds

during ventricular contraction, atrioventricular valves close and first sound produce i.e lub

second heart sound is during ventricular diastole when the semilunar valves close which is called as dub

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