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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.
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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
Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc.
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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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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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Objectives
• Explain the meaning of the term
homeostasis and give an example of a
typical homeostatic mechanism
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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 kinds of organs
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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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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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Anatomical Directions
• Superior—toward the head, upper,
above
• Inferior—toward the feet, lower, below
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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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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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Anatomical Directions
• Proximal—toward or nearest the trunk,
or nearest the point of 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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Anatomical Directions
• Superficial—nearer the body surface
• Deep—farther away from the body
surface
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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 posterior sections
• Transverse plane—horizontal plane that divides a structure into upper and lower sections
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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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Body Cavities
• Ventral cavity
– Thoracic cavity
• Mediastinum—midportion of thoracic cavity;
heart and trachea located in mediastinum
• Pleural cavities—right lung located in right
pleural cavity; left lung in left pleural cavity
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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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Body Cavities
• Ventral cavity
– Abdominopelvic cavity
• Abdominal cavity contains stomach, intestines,
liver, gallbladder, pancreas, and spleen
• Pelvic cavity contains reproductive organs,
urinary bladder, and lowest part of intestine
• Abdominopelvic regions
– Nine regions
– Four quadrants
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Body Cavities
• Dorsal cavity
– Cranial cavity contains brain
– Spinal cavity contains spinal cord
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Body Regions
• Axial region—head, neck, and torso or
trunk
• Appendicular region—upper and lower
extremities
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The Balance of Body Functions
• Survival of the individual and of the genes that make up the body is of the utmost importance
• Survival depends on the maintenance or restoration of homeostasis (relative constancy of the internal environment)– The body uses negative feedback loops and, less
often, positive feedback loops to maintain or restore homeostasis
– Feedback loops involve a sensor, a control center, and an effector
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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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The Balance of Body Functions
• All organs function to maintain
homeostasis
• Ability to maintain balance of body
functions is related to age: peak
efficiency occurs during young
adulthood; diminishing efficiency occurs
after young adulthood