Why is the relaxation period of diastole longer than systole?

Answer 1

systole is an active contraction of the heart that forces blood out. Diastole in a passive refill of the heart and thus takes longer. This is in the normal cardiac cycle

Answer 2

Your heart rate increases when you body’s workload demands more oxygen (oxygen and other nutrients are carried by the blood). When you need more oxygen, your heart rate goes up. As others have said, systole is when your heart squeezes to pump the blood and diastole is when it fills back up before the next pump. The time is takes for one pump (systole) is pretty much the same all the time. But, when the body’s demands are higher and you heart rate increases, diastole time shortens. Most of you body gets blood during systole, but your heart gets its blood/fuel through coronary arteries that fill only during diastole. People with heart problems such as atherosclerosis need a long diastole time to allow those coronary arteries to get all the blood they can. That is why they get chest pain or have heart attacks if they exercise too much or do too much work.

Answer 3

During systole ATP becomes ADP +Pi. . Energy is released for contraction. This takes 0.3 seconds in a single cycle.
Cardiac muscle needs rest for getting ADP to become ATP by phosphorylation. This is diastole and takes longer time of 0.5 seconds in a single cycle.
This is how cardiac muscle is protected from fatigue.

Answer 4

Systole is the forceful contraction of blood from the heart. Because it is forceful, the time to move that volume of blood is short.

Diastole is the passive filling of the heart with blood. Because the pressures are lower, it takes a longer time to move that same volume of blood.

Hope that helps.

Answer 5

What Is Diastole