This document provides an introduction to human anatomy and physiology. It defines anatomy as the study of structure and physiology as the study of function. It discusses the different levels of organization in the human body from the chemical level to the organ system level. It provides an overview of the 11 organ systems and their main components and functions. It also discusses homeostasis and the mechanisms that maintain stable internal conditions in the body. Finally, it introduces anatomical terminology used to describe body positions, planes, sections, and regions.