Editor’s note: The podcast Chasing Life With Dr. Sanjay Gupta explores the medical science behind some of life’s mysteries big and small. You can listen to episodes here . (CNN) — Our skin is considered our largest organ, with a surface area of approximately 15 to 20 square feet (1.4 to 1.9 square meters) — and some put the estimate at least 10 times greater , if the nooks and crannies created by hair follicles and sweat ducts are taken into consideration. It is our body’s first line of defense,