The document discusses the organization of the human body. It describes that cells are the smallest living structures that make up tissues like epithelial, connective, nervous and muscular tissues. These tissues come together to form organs which combine into body systems. The key body planes (midsagittal, frontal, transverse) divide the body and directional terms are used to describe locations. The body contains cavities like the cranial cavity that holds the brain and abdominal regions like the epigastric region below the stomach.