Here's why:

* Anatomy focuses on the structure of the body, including the types of tissues, organs, and organ systems. Understanding the chemical composition of these structures, like the proteins that make up muscles or the lipids that form cell membranes, is essential.

* Physiology focuses on how the body functions. All bodily processes are governed by chemical reactions, from the breakdown of food in digestion to the transmission of nerve impulses.

Therefore, while chemistry is not a branch of anatomy or physiology itself, it is a crucial prerequisite for understanding both.