Chapter 1
An Introduction to the Structure and
Function of the Body

Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc.

Objectives
• Define the terms anatomy and physiology • List and discuss in order of increasing complexity the levels of organization of the body
• Define the term anatomical position

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Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc.

Objectives
• List and define the principal directional terms and sections (planes) used in describing the body and the relationship of body parts to one another
• List the nine abdominopelvic regions and the abdominopelvic quadrants

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Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc.

Objectives
• List the major cavities of the body and the subdivision of each
• Discuss and contrast the axial and the appendicular subdivisions of the body.
Identify a number of specific anatomical regions in each area.

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Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc.

Objectives
• Explain the meaning of the term homeostasis and give an example of a typical homeostatic mechanism

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Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc.

Structural Levels of Organization
• Organization is the most important characteristic of body structure
• The body as a whole is a unit constructed of the following smaller units:
– Atoms and molecules— chemical level
– Cells—the smallest structural units; organizations of various chemicals
– Tissues—organizations of similar cells
– Organs—organizations of different kinds of tissues
– Systems—organizations of many different kind of organs 6
Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc.

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Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc.

Anatomical Position
• Reference position in which the body is standing erect with the feet slightly apart and arms at the sides with palms turned forward
• Anatomical position gives meaning to directional terms

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Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc.

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Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc.

Anatomical Directions
• Anterior— front, in front of (same as ventral in humans)
• Posterior— back, in back of (same as dorsal in humans)

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Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc.

Anatomical Directions
• Medial— toward the midline of a structure • Lateral—away from the midline or toward the side of a structure

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Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc.

Anatomical Directions
• Superior— toward the head, upper, above • Inferior— toward the feet, lower, below

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Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc.

Anatomical Directions
• Proximal— toward or nearest the trunk, or nearest the point origin of a structure
• Distal— away from or farthest from the trunk, or farthest from a structure’s point of origin

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Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc.

Anatomical Directions
• Superficial— nearer the body surface
• Deep— farther away from the body surface 14
Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc.

Planes or Body Sections
• Sagittal plane- lengthwise plane that divides a structure into right and left sections
• Midsagittal— sagittal plane that divides the body into two equal halves
• Frontal (coronal) plane— lengthwise plane that divides a structure into anterior and