Autoregulatsiooni

Autoregulacja, or autoregulation, is the intrinsic ability of a tissue, organ, or system to maintain stable function or perfusion despite changes in external conditions, such as blood pressure, temperature, or metabolic demand. It is distinguished from regulatory processes that depend on external neural or hormonal input, and it operates through local feedback mechanisms to preserve homeostasis.

In physiology, autoregulation most often refers to the regulation of blood flow and oxygen delivery. Mechanisms include the myogenic response, where vascular smooth muscle constricts or dilates in response to changes in transmural pressure; metabolic factors, such as adenosine, carbon dioxide, hydrogen ions, and potassium, that adjust vessel tone to match tissue needs; and, in certain organs, tubuloglomerular feedback that modulates glomerular filtration. Together, these processes enable organs to maintain relatively constant blood flow over a range of systemic pressures.

Organ-specific examples include cerebral autoregulation, which maintains stable cerebral blood flow within roughly 60 to 150 mmHg mean arterial pressure, and renal autoregulation, which stabilizes glomerular filtration rate and renal perfusion via afferent arteriole tone and tubuloglomerular feedback. Coronary and spinal cord autoregulation are additional instances in which local mechanisms preserve tissue viability.

Clinical relevance arises when autoregulation is impaired or overwhelmed, such as in traumatic brain injury, stroke, or hypertensive emergencies, leading to tissue ischemia or edema. Measurements of autoregulatory capacity, including indices derived from blood pressure and flow, aid diagnosis and management. Beyond physiology, autoregulation is a general term for self-regulating feedback systems across disciplines.