autoregulation

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autoregulation

 [aw″to-reg″u-la´shun]
control of certain phenomena by factors inherent in a situation; specifically, (1) maintenance by an organ or tissue of a constant blood flow despite changes in arterial pressure, and (2) adjustment of blood flow through an organ in accordance with its metabolic needs.
heterometric autoregulation those intrinsic mechanisms controlling the strength of ventricular contractions that depend on the length of myocardial fibers at the end of diastole.
homeometric autoregulation those intrinsic mechanisms controlling the strength of ventricular contractions that are independent of the length of myocardial fibers at the end of diastole.

au·to·reg·u·la·tion

(aw'tō-reg'yū-lā'shŭn),
1. The tendency of the blood flow to an organ or part to remain at or return to the same level despite changes in the pressure in the artery that conveys blood to it.
2. In general, any biologic system equipped with inhibitory feedback systems such that a given change tends to be largely or completely counteracted; for example, baroreceptor reflexes form a basis for autoregulation of the systemic arterial blood pressure.

autoregulation

A general term for a locally controlled feedback process—e.g., the regulation of a gene encoding a transcription factor by its own gene product.

au·to·reg·u·la·tion

(aw'tō-reg-yū-lā'shŭn)
1. The tendency of the blood flow to an organ or part to remain at or return to the same level despite changes in the pressure in the artery which conveys blood to it.
2. In general, any biologic system equipped with inhibitory feedback systems such that a given change tends to be largely or completely counteracted; e.g., baroreceptor reflexes form a basis for autoregulation of the systemic arterial blood pressure.
References in periodicals archive ?
Although some studies have shown an increased Pb[CO.sub.2] and decreased pH associated with poor outcome,[18,27] others have been unable to correlate changes in Pb[CO.sub.2] and pH with impaired cerebral blood flow.[13,39] This might be explained by the fact that the ability to autoregulate is impaired in the severely brain injured, and therefore the close relationship between cerebral blood flow and [CO.sub.2] vasoreactivity that exists in normal brain, is lost.[13]
Invasive methods are not appropriate for asymptomatic patients, and measures of cerebral perfusion, such as ocular plethysmography and radionuclear scans, are difficult to apply in various positions.[7] Studies have shown poor correlation between blood pressure changes and cerebral perfusion, probably due to patients' varying ability to autoregulate blood flow.[8] Outcomes, such as falls, myocardial infarctions, strokes, and overall mortality, have been used to determine the significance of the finding of orthostatic hypotension, but this assumes that a measurement on one occasion will be representative of future blood pressure responses.
Under normal circumstances, the kidney has a unique ability to automatically regulate or "autoregulate" its own pressure, which dampens hypertension.
In this setting, the worsening phenomenon may be attributed to decreased nutrient subtract and the ability of the retinal circulation to autoregulate [26].
GR can autoregulate its expression, and prolonged GC exposure induces GR downregulation [21].
Sullivan, "Merkel cell polyomavirus encodes a microRNA with the ability to autoregulate viral gene expression," Virology, vol.
The brain's ability to autoregulate blood flow can be impaired by injury.
The brain, heart and kidney have a remarkable ability to intrinsically autoregulate their blood flow; the brain has been the organ most studied.[11] Cerebral blood vessels normally autoregulate themselves by constricting in response to decreased blood pressure and dilating when the blood pressure falls.
Furthermore, miRNAs can autoregulate their own transcription by targeting some transcription factors to establish negative or positive feedback loops.
Hobbs, "Macrophage endothelial nitric-oxide synthase autoregulates cellular activation and proinflammatory protein expression," The Journal of Biological Chemistry, vol.

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