Chemical messengers produced by endocrine glands are called

Before the can be observed by using a transmission electron microscope, cells are sliced into very thin sections. what disadvantage does this procedure present in the study of cellular parts

An easy way to calculate the amount of energy available at each level is to what?

What is the difference between the conducting zone and the respiratory zone of the respiratory system? the conducting zone is a series of cavities and tubes that move air to the respiratory zone where gases exchange with the bloodstream. the conducting zone exchanges gases between the lungs and the alveoli and the respiratory zone is a series of cavities and tubes that move air to the conducting zone. the conducting zone moves oxygen into the cells and the respiratory zone takes carbon dioxide away from the cells. the conducting zone moves oxygen into the bloodstream and the respiratory zone takes carbon dioxide away from the bloodstream.