The prefrontal cortex is the last area of the brain to reach full structural and functional maturity. This region is responsible for executive functions, including complex decision-making, planning, impulse control, and social behavior. Because its development continues well into the mid-twenties, adolescents and young adults often exhibit higher levels of risk-taking and emotional volatility compared to older adults, as the neural pathways for self-regulation are still being refined.

The prefrontal cortex is the anterior part of the frontal lobes and is critical for 'executive functions.' These include complex cognitive behaviors such as planning, decision-making, personality expression, moderating social behavior, and orchestrating thoughts and actions in accordance with internal goals.

The orbitofrontal cortex is a critical region of the prefrontal cortex involved in cognitive processing of decision-making. It plays a significant role in evaluating rewards, regulating emotional responses, and facilitating behaviors necessary for survival. These functions allow organisms to adapt to changing environments by assessing the value of various stimuli.

The parasympathetic nervous system is often referred to as the 'rest and digest' system. It works to conserve energy, slow the heart rate, increase intestinal and gland activity, and relax sphincter muscles in the gastrointestinal tract. By counteracting the sympathetic nervous system, it helps the body return to a state of homeostasis after a stressful event, facilitating recovery and maintenance of bodily systems.

The autonomic nervous system is divided into the sympathetic and parasympathetic branches. The sympathetic division prepares the body for 'fight or flight' responses, while the parasympathetic division acts as the 'rest and digest' system. It works to slow down heart rate, stimulate digestion, and return the body to a state of homeostasis after a stressful event has passed.

The autonomic nervous system is divided into the sympathetic and parasympathetic branches. The parasympathetic division is responsible for the 'rest and digest' state, which restores the body and conserves energy by slowing the heart rate and stimulating digestion. In contrast, the sympathetic division triggers the 'fight-or-flight' response. The somatic nervous system governs voluntary muscle movement, and the limbic system is primarily associated with emotion and memory, not autonomic energy regulation.

The parasympathetic nervous system is characterized by craniosacral outflow. This means its preganglionic neurons originate in the brainstem (including the vagus nerve, cranial nerve X) and the sacral segments of the spinal cord, facilitating 'rest and digest' functions.

Acetylcholine, adrenaline (epinephrine), and dopamine are all well-documented neurotransmitters. Acetylcholine is vital for muscle contraction and memory, adrenaline is involved in the fight-or-flight response, and dopamine is central to reward and motor control. Each of these chemicals is essential for the proper functioning of the nervous system and the transmission of signals between neurons.

The dopamine hypothesis of schizophrenia suggests that overactivity of dopamine in certain brain pathways is a primary factor in the development of psychotic symptoms. While other conditions involve dopamine, it is most centrally linked to the pathophysiology of schizophrenia.

Somatotropin, commonly known as growth hormone (GH), is secreted by the anterior pituitary gland. When excessive amounts are produced during childhood, before the closure of the epiphyseal plates in the bones, it results in gigantism, characterized by abnormal and rapid growth in height and body size. This condition highlights the critical role of endocrine regulation in human development.