Autoregulation

Autoregulation is a process within many biological systems, resulting from an internal adaptive mechanism that works to adjust (or mitigate) that system's response to stimuli. While most systems of the body show some degree of autoregulation, it is most clearly observed in the kidney, the heart, and the brain. Perfusion of these organs is essential for life, and through autoregulation the body can divert blood (and thus, oxygen) where it is most needed. Autoregulation is a process within many biological systems, resulting from an internal adaptive mechanism that works to adjust (or mitigate) that system's response to stimuli. While most systems of the body show some degree of autoregulation, it is most clearly observed in the kidney, the heart, and the brain. Perfusion of these organs is essential for life, and through autoregulation the body can divert blood (and thus, oxygen) where it is most needed. More so than most other organs, the brain is very sensitive to increased or decreased blood flow, and several mechanisms (metabolic, myogenic, and neurogenic) are involved in maintaining an appropriate cerebral blood pressure. Brain blood flow autoregulation is abolished in several disease states such as traumatic brain injury, stroke, brain tumors, or persistent abnormally high CO2 levels. Homeometric autoregulation, in the context of the circulatory system, is the heart's ability to increase contractility and restore stroke volume when afterload increases. Homeometric autoregulation occurs independently of cardiomyocyte fiber length, via the Bowditch and/or Anrep effects. This is in contrast to heterometric regulation, governed by the Frank-Starling law, which results from a more favorable positioning of actin and myosin filaments in cardiomyocytes as a result of changing fiber lengths.