Anatomy & Physiology

Anatomy & Physiology Study Guide

Chapter 3: Cellular Level of Organization Cells are the basic building blocks of all living things. Cells are microscopic—a typical cell is only about 1.1mm in diameter. The basic concepts of cellular theory can be summarized as follows: • The building blocks of all living things are known as cells. • All cells come from the division of preexisting cells. • Cells are the smallest functional units. • Homeostasis is maintained at the cellular level. Cytology is the study of cellular structure and function and is part of cell biology. Most living organisms are eukaryotic and composed of multiple cells with organelles. Other organisms are prokaryotic (simple and single-celled). The human body contains two general classes of cells: sex cells and somatic cells. Sex cells (also called germ cells or reproductive cells) are either the sperm of males or the oocytes of females. Somatic cells (soma, body) include all the other cells in the human body. 3.1 Cell Structure

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