Cells are made of proteins, which are a type of molecule, and water, which is another molecule, and other things which are all made of molecules. Proteins are made of carbon, hydrogen, oxygen, and other elements. So we know that the molecules that make up the cells of the body are made of atoms.

However, at the most basic level, your body—and, in fact, all of life, as well as the nonliving world—is made up of atoms, often organized into larger structures called molecules. Atoms and molecules follow the rules of chemistry and physics, even when they’re part of a complex, living, breathing being.

About 99 percent of your body is made up of atoms of hydrogen, carbon, nitrogen and oxygen. You also contain much smaller amounts of the other elements that are essential for life.

Until the 18th century the bodies of executed criminals served the sole source of cadavers for anatomists in United States. In 1790, a federal law was passed which permitted federal judges to add dissection to a death sentence for murder.

Selling hearts, kidneys and tendons for transplant is illegal. But no federal law governs the sale of cadavers or body parts for use in research or education. Few state laws provide any oversight whatsoever, and almost anyone, regardless of expertise, can dissect and sell human body parts.

They practice appendectomies—procedures done 280,000 times each year in the U.S.—on cadavers. Then surgical residents are sent back to the lab to study the anatomy again.

Vivisection (from Latin vivus ‘alive’, and sectio ‘cutting’) is surgery conducted for experimental purposes on a living organism, typically animals with a central nervous system, to view living internal structure.

Every single cat, frog, pig, rat, rabbit, or other animal who ends up on a dissection tray was once alive. And NONE of them wanted to die just so that you can cut apart a corpse. If you and others like you choose not to dissect, millions of these animals won’t be killed, period.

Cats, frogs, fetal pigs, grasshoppers, mink, earthworms, rats, mice, dogs, pigeons, and turtles are just some of the species used. While most of the animals used in schools and universities are purchased as dead specimens, many are subjected to painful and lethal procedures while still alive.

Dissection is bad for the environment. Many of the animals harmed or killed for classroom use are caught in the wild, often in large numbers. Plus, the chemicals used to preserve animals are unhealthy (formaldehyde, for example, irritates the eyes, nose, and throat).