he condition in which the body's internal environment remains relatively constant within physiological limits - ANS-homeostasis a plane at a right angle to a midsagittal plane that divides the body or organs into anterior and posterior portions - ANS-frontal-coronal cavity superior to the diaphragm that contains two pleural cavities, the mediastinum, and the pericardial cavity - ANS-thoracic a position of the body universally used in anatomical descriptions in which the body is erect, the head is level, the eyes face forward, and the feet are flat on the floor - ANS-anatomical position a plane that divides the body or organs into left and right portions - ANS-sagittal inferior to the diaphragm and subdivided into a superior and abominal cavity and an inferior pelvic cavity - ANS-abdominopelvic cavity lying face up - ANS-supine a vertical plane through the midline of the body that divides the body or organs into equal right and left sides; also called a median plane - ANS-midsagittal the branch of biology concerned with the structure and function of plant and animal cells - ANS-cytology lying face down - ANS-prone