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The detailed study of physiologic system structure and function has its foundations in physical and chemical laws and the molecular and cellular makeup of each tissue and organ system. This first section provides an overview of the basic building blocks that provide the important framework for human physiology. It is important to note here that these initial sections are not meant to provide an exhaustive understanding of biophysics, biochemistry, or cellular and molecular physiology, rather they are to serve as a reminder of how the basic principles from these disciplines contribute to medical physiology discussed in later sections.

In the first part of this section, the following basic building blocks are introduced and discussed: electrolytes; carbohydrates, lipids, and fatty acids; amino acids and proteins; and nucleic acids. Students are reminded of some of the basic principles and building blocks of biophysics and biochemistry and how they fit into the physiologic environment. Examples of direct clinical applications are provided in the Clinical Boxes to help bridge the gap between building blocks, basic principles, and human physiology. These basic principles are followed up with a discussion of the generic cell and its components.

In the second part of this introductory section, we take a cellular approach to lay groundwork for understanding groups of cells that interact with many of the systems discussed in future chapters. The first group of cells presented contribute to inflammatory reactions in the body. These individual players, their coordinated behavior, and the net effects of the “open system” of inflammation in the body are discussed in detail. The second group of cells discussed are responsible for the excitatory responses in human physiology and include both neuronal and muscle cells. A fundamental understanding of the inner workings of these cells and how they are controlled by their neighboring cells helps the student to understand their eventual integration into individual systems discussed in later sections.

This first section serves as an introduction, refresher, and quick source of material to best understand systems physiology presented in the later sections. For detailed understanding of any of the chapters within this section, several excellent and current textbooks that provide more in-depth reviews of principles of biochemistry, biophysics, cell physiology, and muscle and neuronal physiology are available. Students who are intrigued by the overview provided in this first section are encouraged to visit such texts for a more thorough understanding of these basic principles.

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