Pre-Algebra on Khan Academy: No way, this isn't your run of the mill arithmetic. This is Pre-algebra. You're about to play with the professionals. Think of pre-algebra as a runway.
Coronary heart disease. Coronary heart disease (CHD) is the leading cause of heart attacks. CHD is a condition in which the coronary arteries (the major blood vessels that supply the heart with blood) get clogged up with deposits of cholesterol. These deposits are called plaques.
Most heart attacks are likely caused by an imbalance in your central nervous system (CNS) and your autonomic (or unconscious) nervous system (ANS), which controls the function of our internal organs By Thomas S. Cowan, MD