The maintenance of the body"s internal environment within a narrow physiological range. Controlled by the hypothalamus: temperature, blood composition. Optic chiasm and pituitary gland located right below it. Along the walls of the third ventricle. Extensive connections in the brain stem & telencephalon: medial. Extensive connections in the brain stem & telencephalon: periventricular. Receives much of its input from the other two zones. Cells of this region lie right next to the wall of the third ventricle. Mix of neurons with different functions reside here. Extend axons down toward stalk of pituitary gland. Extend around optic chiasm, down stalk, and reside in posterior lobe. Neurons release chemical substances directly into the capillaries of lobe. Kidneys can also communicate with posterior pituitary gland. Has direct effects on blood vessels and kidney, increase blood pressure. Gives us the urge to drink more: anterior. Controlled by parvocellular neurosecretory cells of the periventricular area.