AP PSYCHOLOGY

Detailed explanation-1: -The reticular activating system (RAS) is composed of an ascending tract and a descending tract. The ascending RAS is responsible for human consciousness level and integrates the functions of the brain stem with cortical, cerebellar, thalamic, hypothalamic, and sensory receptor functions.

Detailed explanation-2: -The brain stem connects the cerebrum with the spinal cord. It contains a system of nerve cells and fibers (called the reticular activating system) located deep within the upper part of the brain stem. This system controls levels of consciousness and alertness.

Detailed explanation-3: -The reticular formation nuclei are found deep within the brainstem, along its length. It is easier to appreciate the approximate location of these nuclei if they are superimposed on a posterior view of the brainstem with the cerebellum removed.

Detailed explanation-4: -The reticular formation is a region in the pons involved in regulating the sleep-wake cycle and filtering incoming stimuli to discriminate irrelevant background stimuli. It is essential for governing some of the basic functions of higher organisms, and is one of the phylogenetically oldest portions of the brain.

Detailed explanation-5: -The hypothalamus, a peanut-sized structure deep inside the brain, contains groups of nerve cells that act as control centers affecting sleep and arousal.