What is the Origin of Sympathetic Nervous System Upregulation?

The term is derived from the "Sympathetic Nervous System," one of the two main branches of the Autonomic Nervous System, and "upregulation," a biological term signifying an increase in a response or process. The concept is fundamental to stress physiology and the body's adaptive capacity. Understanding this process is key to managing stress-related health issues.

What is the Mechanism of Sympathetic Nervous System Upregulation?

Upregulation is initiated by signals from the hypothalamus and brainstem nuclei in response to perceived threats or intense physical exertion. These signals travel via preganglionic neurons to the sympathetic ganglia, triggering the release of acetylcholine, which in turn stimulates postganglionic neurons to release norepinephrine onto target organs. Concurrently, the adrenal medulla is stimulated to release epinephrine and norepinephrine into the bloodstream, amplifying and sustaining the systemic response.

Sympathetic Nervous System Upregulation ∞ Area

Sympathetic Nervous System Upregulation

Meaning

Sympathetic Nervous System Upregulation is the acute or chronic increase in the overall activity and output of the sympathetic division of the autonomic nervous system. This state is characterized by physiological changes designed to prepare the body for immediate action, often termed the ‘fight or flight’ response. Upregulation involves increased heart rate, peripheral vasoconstriction, and the mobilization of glucose and fatty acids for energy. While acutely beneficial for survival, chronic upregulation is a state of allostatic overload that can severely compromise cardiovascular and hormonal health.