This chapter from Outdoor Emergency Care: A Patroller's Guide to Medical Care (6th edition) serves as a foundational guide to human anatomy and physiology for emergency care technicians. Its primary purpose is to equip students with the essential knowledge of body structures and functions necessary for effective patient assessment and communication. The text systematically covers various body systems, including the respiratory, cardiovascular, nervous, digestive, urinary, endocrine, integumentary, skeletal, muscular, reproductive, lymphatic, and immune systems, detailing their components, functions, and interconnections. Emphasis is placed on understanding anatomical terms, body directions, and movements to accurately describe injuries and communicate with other medical personnel. The chapter also highlights the crucial role of this knowledge in recognizing and managing injuries and illnesses.