Recall the functions of the skin

Scientists who study the anatomy of the systems in the human body focus their studies on

During polarization,potassium has a blank charge,sodium has a blank ch arge ,and calcium has a b l ank. charge

Ihave a really high metabolism and only weigh 70 pounds (13 almost 14). people always ask me two questions: do you ever eat and how do you eat so much and stay so skinny.i am worried that a high metabolism wont me forever. what are some safe steps i can take to maintain being fit. (also, i already work out i am a dacer so i get cardio a lot)