Molecular clouds may collide with each other, or a nearby supernova explosion can be a trigger, sending shocked matter into the cloud at very high speeds. Alternatively, galactic collisions can trigger massive starbursts of star formation as the gas clouds in each galaxy are compressed and agitated by tidal forces.
Coordinated contractions of cardiac muscle cells in the heart propel blood out of the atria and ventricles to the blood vessels of the left/body/systemic and right/lungs/pulmonary circulatory systems.This complex mechanism illustrates systole of the heart.ardiac muscle cells, unlike most other tissues in the body, rely on an available blood and electrical supply to deliver oxygen and nutrients and remove waste products such as carbon dioxide. The coronary arteries help fulfill this function.
Calcium and Cardiac Muscle. The heart is formed from specialized muscle cells called cardiomyocytes that work automatically without skipping a single beat. Like other muscles, the cardiac muscles require calcium to contract and squeeze blood out of the heart and into the arteries.he heart is formed from specialized muscle cells called cardiomyocytes that work automatically without skipping a single beat. Like other muscles, the cardiac muscles require calcium to contract and squeeze blood out of the heart and into the arteries.