II. The Central Nervous System D. Organization of the Nervous System 11. CNS: brain and spinal cord which contains more than 90% of the body’s neurons 12. PNS: nerves connecting brain and cord to every other part of the body E. The Brain 13. The Central Core xiii. Hindbrain: plays essential role in basic life processes a. Medulla controls breathing, heat rate, and blood pressure b. Pons regulate sleep-awake cycle c. Cerebellum is responsible for balance and reflexes, and coordination. Contains more neurons than the rest of the brain. i. Cerebellar dysfunction may include autism, schizophrenia, and ADD xiv. Midbrain: Hearing, sight, pain registration, eating, drinking, sex, emotion d. Site of the reticular formation whose main job is to send alter signals to the higher parts of the brain in response to incoming messages. Regulates attention and alertness. * Forebrain a. Contains the thalamus which is the relay station of the brain. Regulates higher brain centers and peripheral nervous system b. Not fully formed until after adolescence 14. The Limbic System xv. Hypothalamus: Hunger, thirst, sex drive, body temperature, rage, terror, and pleasure xvi.