This video describes how the circulatory system works, how disease can affect blood vessels (atherosclerosis), and how doctors use angiography to test for coronary artery blockage.

This animation shows the immune system reacting (or overreacting) at the cellular level. It describes what happens when an allergen, like dander or pollen, enters the body. It also shows how some allergy medicines work, like anti-histamines.

This animation shows what angioplasty and stent deployment look like if you could see inside of the blood vessels, up close. There is no narration, but the "balloon" being opened is the angioplasty procedure while the "chicken-wire" cylinder is the stent.

This 3D animation explains how the heart muscle contracts to pump blood throughout the body. The action of cells at the microscopic level affects the function of the entire cardiovascular system, as the video explains.