This video combines animation and real footage of the heart to demonstrate how the atrial, pulmonic, mitral, and tricuspid valves of the heart work. The coordinated opening and closing of these valves is what allows the heart to provide blood flow and pressure in one direction, toward the lungs and body.

Normal Pressure Hydrocephalus or NPH is described in this animation showing the ventricles of the brain and the flow of cerebrospinal fluid or CSF. The cause is not precisely known but can caused nausea, vomiting, headache, and problems walking among other symptoms.