heart
The heart
The heart contracts and relaxes during a cardiac cycle.
Typically that organ is your heart. It contracts and relaxes 72 times per minute, day and night, till your death. That means for hundred years.
The first part of the cardiac cycle is called diastole, which is when the heart relaxes and fills with blood. This is followed by systole, when the heart contracts to pump blood out to the body.
It is called your diaphragm.
The spaces between pulsations are called diastole. This is the phase of the cardiac cycle when the heart muscle relaxes and fills with blood before it contracts again during systole.
When the bicep contracts, the tricep relaxes. These pair of muscles are known as antagonists which means as one contracts, the other relaxes and vice versa.
muscles
When lowering arm biceps relax and triceps contracts. When one contracts the other relaxes when you move it forward and downward.
It Contracts
It relaxes