c. Both the nervous system and the endocrine system are important to the maintenance
of homeostasis.
3. Positive Feedback Mechanisms
a. A positive feedback mechanism causes the variable to change in the same direction
as the original change, resulting in a greater deviation from the set point.
4. Homeostatic imbalance often results in disease.
V. The Language of Anatomy (pp. 11–20 ; Figs. 1.7–1.12; Table 1.1)
A. Anatomical Position and Directional Terms (pp. 11–13; Table 1.1)
1. Anatomical position is a position in which the body is erect, palms face forward, and
thumbs point away from the body.
2. Directional terms are used to explain exactly where one body part is in relation to
another.
B. Regional Terms (p. 13; Fig. 1.7)
1. There are two fundamental divisions of the body.
a. The axial region includes the head, neck, and trunk.
2. Regional terms designate specific areas within the axial and appendicular divisions.
C. Anatomical variability does exist within internal organs, although well over 90% of all
structures in the human body match textbook descriptions (p. 14).
D. Body Planes and Sections (p. 14; Fig. 1.8)
1. Body planes are flat surfaces that lie at right angles to each other.
a. Sagittal plane: a vertical plane that separates the body into right and left parts.
i. Median, or midsagittal plane: lies exactly along the body’s midline.
2. Sections are cuts made along specific planes.
a. Transverse section, or cross section, is a cut made along the transverse plane.
b. Oblique sections are cuts made at angles between the horizontal and vertical planes.
E. Body Cavities and Membranes (pp. 14–20; Figs. 1.9–1.12)