Every cell in the human body has a sex, which means that men and women are different right down to the cellular level. Yet too often, research and medicine ignore this insight — and the often startlingly different ways in which the two sexes respond to disease or treatment.

Paula Johnson, MD, MPH, founder of the the Center for Cardiovascular Disease in Women at Brigham and Women’s Hospital in Boston, describes in this thought-provoking video, lumping everyone in together means we essentially leave women’s health to chance. It’s time to rethink.