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hypothalamus hy·po·thal·a·mus (hī'pō-thāl'ə-məs)
The part of the brain that lies below the thalamus, forming the major portion of the ventral region of the diencephalon, and that regulates bodily temperature, certain metabolic processes, and other autonomic activities.
The part of the brain in vertebrate animals that lies below the thalamus and cerebrum. The hypothalamus controls the autonomic nervous system and the secretion of hormones by the pituitary gland. Through these nerve and hormone channels, the hypothalamus regulates many vital biological processes, including body temperature, blood pressure, thirst, hunger, and the sleep-wake cycle.