The heart is just a muscle that pumps blood through the body. When the heart contracts it is pushing the blood around your body. There is a nice, though not too in depth, video on the NOVA website:
See the Related Link.
Heart pumps out blood into major vessels(aorta,pulmonary arteries)
they open to allow the blood through then close again so the blood can't flow back
The heart contracts and relaxes during a cardiac cycle.
arteries
Contractions,or beats .
it contracts
It contracts to push blood throughout the body.
Heart pumps out blood into major vessels(aorta,pulmonary arteries)
Diastolic and systolic is when your heart contracts and relaxes.
the valve would fail to close or would invert when the heart contracts, this may cause heart failure.
Timer for recovery before the heart contracts again
When the Deltoid contracts the humerus abducts.
When the bicep contracts the triceps relax
When a muscle contracts, it shortens in length.
Blood flows to the heart when the ventricle contracts
heart
they open to allow the blood through then close again so the blood can't flow back