Review of Key Concepts
Anatomical Position (p. 30)
1. Human anatomy is described with reference to a standard anatomical position, which avoids the ambiguity of terms that depend on the position of the body.
Anatomical Planes (p. 31)
1. Internal structure is often depicted along one of three mutually perpendicular planes through the body: the sagittal, frontal, and transverse planes.
Directional Terms (p. 31)
1. The position of one structure relative to another is often described by such pairs of terms as superior-inferior, medial-lateral, proximal-distal, and others (table A.1).
Surface Anatomy (p. 32)
- The body is divided into a central axial region (head, neck, trunk) and appendicular region (limbs).
- The abdomen can be divided into either four quadrants or nine regions for describing the locations of structures, symptoms, or abnormal conditions (fig. A.6).
- Each limb is divided into five regions from proximal to distal.
Body Cavities and Membranes (p. 36)
- The body is internally divided into a dorsal and ventral body cavity. The organs in these cavities are called the viscera.
- The body cavities are lined with serous membranes: the meninges around the brain and spinal cord, pleurae around the lungs, pericardium around the heart, and peritoneum in the abdominal cavity.
- The last three of these membranes have outer and inner parietal and visceral layers, respectively, with lubricating fluid between the layers (pleural, pericardial, and peritoneal fluid).
- Retroperitoneal organs such as the kidneys and pancreas lie between the peritoneum and body wall rather than within the peritoneal cavity.
- The peritoneum continues as a mesentery that suspends the intestines and other organs from the dorsal body wall, a serosa over the surface of some abdominal organs, and two omenta attached to the stomach.
Organ Systems (p. 38)
- The body has 11 organ systems: the integumentary, skeletal, and muscular systems for protection, support, and movement; the nervous and endocrine systems for internal communication; the circulatory and lymphatic systems for fluid transport; the respiratory, urinary, and digestive systems for input and output; and the reproductive system for producing offspring.
- The body also has an immune system for protection from disease, but this is not an organ system; it is a collection of cells that populate all the organ systems.
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This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.
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