Science (Anatomy & Physiology, Biology, Chemistry)

Cell → tissue → organ → organ system → organism. Cells of one type group into tissues, tissues form organs, organs work together as organ systems, and all systems together make the organism.

The cell. It is the smallest unit that can carry out all life processes; all organisms are made of one or more cells.

The body is standing erect, facing forward, with feet flat and slightly apart, arms at the sides, and palms facing forward (forearms supinated). All directional terms are described relative to this position.

Superior means toward the head or upper part of a structure (above); inferior means toward the feet or lower part (below). Example: the heart is superior to the stomach.

Anterior (ventral) means toward the front of the body; posterior (dorsal) means toward the back. Example: the sternum is anterior to the spine.