The Human Cell Cells are the very essence of life . Cells may be defined as the basic living, structural, and functional units of the human body. They vary greatly in size, chemical composition, and function, but each one is a remarkable miniaturization of human life. Cells move, grow, ingest food and excrete wastes, react to their environment, and even reproduce. This chapter provides a brief review of the basics of a cell, including cellular components, communication, energy, and transport. An overview of the natural life span of a typical cell is provided because of its importance in nutrition and disease. multicellular organisms Cells of all multicellular organisms are called eukaryotic cells (from the Greek eu, meaning “true,” and karyon, “nucleus”). Eukaryotic cells evolved from simpler, more primitive cells called prokaryotic cells (from the Greek meaning “before nucleus”).The major distinguishing feature between the two cell types is that eukaryotic cells possess a defined n...
