Here's why:

* Gross Anatomy: This branch of anatomy focuses on the large-scale structures of the body, the ones visible to the naked eye. It deals with the organs, their shapes, their locations, and how they are connected.

* Organ Physiology: This branch of physiology focuses on how organs work, their individual functions, and how they interact to keep the body running.

In simpler terms:

* Gross anatomy answers the question "What does it look like?"

* Organ physiology answers the question "How does it work?"

For example:

* Gross Anatomy: The heart is a muscular organ located in the chest.

* Organ Physiology: The heart pumps blood throughout the body, supplying oxygen and nutrients to tissues.