Final answer:
Depression and schizophrenia are examples of functional disorders, which are psychological conditions without identifiable brain pathology, involving imbalances in neurotransmitters like dopamine, glutamate, and serotonin.
Step-by-step explanation:
Depression and schizophrenia are both examples of mental illnesses, which are nervous system disorders that can severely impede a person's thinking, mood, or ability to relate to others. These examples specifically fall under the category of functional disorders. Functional disorders are psychiatric conditions where the primary dysfunction is in the psychological domain and there is no identifiable brain or organic pathology. Schizophrenia is a complex mental disorder characterized by hallucinations, delusions, and cognitive issues, while depression involves a persistently depressed mood and loss of interest in activities. Both conditions are believed to involve imbalances in neurotransmitters, the brain's chemical messengers. Schizophrenia is often associated with problems in dopamine and glutamate signaling, while depression is linked to alterations in serotonin, norepinephrine, and possibly dopamine levels. Treatments for both illnesses generally involve medications and therapy to manage symptoms, but these conditions are typically chronic and require long-term management.