Introduction to Human Anatomy

Human anatomy is the study of the structure of the human body. This guide introduces the fundamental concepts of anatomical study, including anatomical position, directional terms, body planes, and the organization of the body into systems.

Anatomical position is the standard reference position: standing upright, facing forward, arms at the sides with palms facing forward, and feet slightly apart. All anatomical descriptions are made relative to this position.

The body is organized hierarchically from atoms to the organism level: atoms form molecules, which form organelles, which form cells, which form tissues (epithelial, connective, muscle, nervous), which form organs, which form organ systems, which together form the organism.

The 12 major organ systems work together to maintain homeostasis, the stable internal environment necessary for life.