Newtons third law is action/reaction, for every action there is an equal opposite force
Homeostasis or the source of body heat
Because they are made to perform two different functions. Cells are part of tissues that are part of organs that perform a certain function. For example, your bone cells are made to make blood cells, so they wouldn’t be in your lungs as well.
Adrenaline, Cortisol, Norepinephrine.