During pulmonary circulation, what leaves the heart?

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 dancer so i get cardio a lot)

John is jogging on a winter day. the outdoor temperature is 31° f. yet his body temperature is 98°f. which term best describes the process causing this difference in temperature?

The real advantage to hydrostatic weighing is that it a. can be done anywhere with no equipment b. gives one of the most accurate measurements of body fat c. uses calipers to measure body fat select the best answer from the choices provided.