Final answer:
The hypothalamus is the key area of the brain responsible for reflex control of the autonomic system, coordinating the balance between the sympathetic and parasympathetic responses and integrating with both autonomic and endocrine systems.
Step-by-step explanation:
Control Center for Reflex Control of the Autonomic System
The hypothalamus is the most directly involved area of the brain in the reflex control of the autonomic system. It is considered the master control center for homeostasis, integrating both the autonomic and endocrine systems. The hypothalamus regulates the balance between the sympathetic and parasympathetic systems, impacting various organs' tone. It receives input from cerebral structures and projects to the brain stem and spinal cord through the medial forebrain bundle and the dorsal longitudinal fasciculus. Furthermore, it interacts with the limbic system, such as the amygdala, influencing emotional responses on visceral functions.
Other important brain stem nuclei include the solitary nucleus, which contributes to the regulation of cardiovascular function, and the dorsal motor nucleus of the vagus nerve, which controls parasympathetic functions like decreasing the heart rate and promoting digestion.