What is the study of structures of a human body that can be seen with the naked eye called?

This is the study of anatomy. Anything you can see with the eye is an anatomy part - a bone, an internal organ, or even a muscle. You can physically see the heart when it is take out of a body without any kind of magnifying glass or microscope. Being able to see these parts with the human eye makes doing surgeries and regular check ups easier on the doctors. Most doctors will have taken years of anatomy classes to keep up on their anatomy.

These are often accompanied by the studies of biology, chemistry, and other sciences that can help them in their pursuit to help other humans get better. Physiology, on the other hand, is the study of how the body parts work.