autoregulatory increase of blood flow to a tissue
Autoregulation - wikipedia Autoregulation Jump to : navigation , search 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 . Contents ( hide ) 1 Cerebral autoregulation 2 Homeometric and heterometric autoregulation of the heart 3 Coronary circulatory autoregulation 4 Renal autoregulation 5 Autoregulation of genes 6 See also 7 References Cerebral autoregulation ( edit ) Main article : Cerebral autoregulation 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 and heterometric autoregulation of the heart ( edit ) 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 . Via the Bowditch effect , positive inotropy occurs secondary to an increased cardiac frequency . The exact mechanism for this remains unknown , but it appears to be the result of an increased exposure of the heart to contractile substances arising from the increased flow caused by an increased cardiac frequency . Via the Anrep effect , positive inotropy occurs secondary to increased ventricular pressure . 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 . Coronary circulatory autoregulation ( edit ) Since the heart is a very aerobic organ , needing oxygen for the efficient production of ATP & Creatine Phosphate from fatty acids ( and to a smaller extent , glucose & very little lactate ) , the coronary circulation is auto regulated so that the heart receives the right flow of blood & hence sufficient supply of oxygen . If a sufficient flow of oxygen is met and the resistance in the coronary circulation rises ( perhaps due to vasoconstriction ) , then the coronary perfusion pressure ( CPP ) increases proportionally , to maintain the same flow . In this way , the same flow through the coronary circulation is maintained over a range of pressures . This part of coronary circulatory regulation is known as auto regulation and it occurs over a plateau , reflecting the constant blood flow at varying CPP & resistance . The slope of a CBF ( coronary blood flow ) vs. CPP graph gives 1 / Resistance . Renal autoregulation ( edit ) Main article : Tubuloglomerular feedback Regulation of renal blood flow is important to maintaining a stable glomerular filtration rate ( GFR ) despite changes in systemic blood pressure ( within about 80 - 180 mmHg ) . In a mechanism called tubuloglomerular feedback , the kidney changes its own blood flow in response to changes in sodium concentration . The sodium chloride levels in the urinary filtrate are sensed by the macula densa cells at the end of the ascending limb . When sodium levels are moderately increased , the macula densa releases ATP and reduces prostaglandin E2 release to the juxtaglomerular cells nearby . The juxtaglomerular cells in the afferent arteriole constrict , and juxtaglomerular cells in both the afferent and efferent arteriole decrease their renin secretion . These actions function to lower GFR . Further increase in sodium concentration leads to the release of nitric oxide , a vasodilating substance , to prevent excessive vasoconstriction . In the opposite case , juxtaglomerular cells are stimulated to release more renin , which stimulates the renin -- angiotensin system , producing angiotensin I which is converted by Angio - Tensin Converting Enzyme ( ACE ) to angiotensin II . Angiotensin II then causes preferential constriction of the efferent arteriole of the glomerulus and increases the GFR . Autoregulation of genes ( edit ) This is so - called `` steady - state system '' . An example is a system in which a protein P that is a product of gene G `` positively regulates its own production by binding to a regulatory element of the gene coding for it , '' and the protein gets used or lost at a rate that increases as its concentration increases . This feedback loop creates two possible states `` on '' and `` off '' . If an outside factor makes the concentration of P increase to some threshold level , the production of protein P is `` on '' , i.e. P will maintain its own concentration at a certain level , until some other stimulus will lower it down below the threshold level , when concentration of P will be insufficient to make gene G express at the rate that would overcome the loss or use of the protein P . This state ( `` on '' or `` off '' ) gets inherited after cell division , since the concentration of protein a usually remains the same after mitosis . However , the state can be easily disrupted by outside factors . Similarly , this phenomenon is not only restricted to genes but may also apply to other genetic units , including mRNA transcripts . Regulatory segments of mRNA called a Riboswitch can autoregulate its transcription by sequestering cis - regulatory elements ( particularly the Shine - Dalgarno sequence ) located on the same transcript as the Riboswitch . The Riboswitch stem - loop has a region complementary to the Shine - Dalgarno but is sequestered by complimentary base pairing in the loop . With sufficient ligand , the ligand may bind to the stem - loop and disrupt intermolecular bonding , resulting in the complimentary Shine - Dalgarno stem - loop segment binding to the complimentary Riboswitch segment , preventing Ribosome from binding , inhibiting translation . See also ( edit ) Look up autoregulation in Wiktionary , the free dictionary . Homeostasis Renin -- angiotensin system References ( edit ) Jump up ^ Autoregulation Jump up ^ Figaji , Anthony A. ; Eugene Zwane ; A. Graham Fieggen ; Andrew C. Argent ; Peter D. Le Roux ; Peter Siesjo ; Jonathan C. Peter ( 2009 ) . `` Pressure autoregulation , intracranial pressure , and brain tissue oxygenation in children with severe traumatic brain injury '' . Journal of Neurosurgery . Pediatrics. 4 ( 5 ) : 420 -- 428 . doi : 10.3171 / 2009.6. PEDS096 . ISSN 1933 - 0715 . PMID 19877773 . Jump up ^ Budohoski K.P. ; Czosnyka M. ; Kirkpatrick P.J. ; Smielewski P. ; Pickard J.D. ( 2013 ) . `` Clinical relevance of cerebral autoregulation following subarachnoid haemorrhage '' . Nat. Rev. Neurol. 9 ( 3 ) : 152 -- 63 . doi : 10.1038 / nrneurol. 2013.11 . PMID 23419369 . Jump up ^ Paulson , O.B. ; S. Strandgaard ; L. Edvinsson ( 1990 ) . `` Cerebral autoregulation '' . Cerebrovascular and Brain Metabolism Reviews . 2 ( 2 ) : 161 -- 192 . ISSN 1040 - 8827 . PMID 2201348 . Jump up ^ Panerai , R.B. ; S.T. Deverson ; P. Mahony ; P. Hayes ; D.H. Evans ( 1999 ) . `` Effect of CO2 on dynamic cerebral autoregulation measurement '' . Physiological Measurement. 20 ( 3 ) : 265 . doi : 10.1088 / 0967 - 3334 / 20 / 3 / 304 . ISSN 0967 - 3334 . PMID 10475580 . Retrieved 2015 - 01 - 24 . Jump up ^ Sarnoff SJ , Mitchell JH , Gilmore JP , Remensnyder JP ( 1960 ) . `` Homeometric autoregulation in the heart '' ( PDF ) . Circulation Research . 8 ( 5 ) : 1077 -- 1091 . doi : 10.1161 / 01. res. 8.5. 1077 . PMID 13746560 . ^ Jump up to : Monroe , R.G. ; Gamble , W.J. ; Lafarge , C.G. ; Vatner , S.F. ( 1974 - 01 - 01 ) . Porter , Ruth ; Fitzsimons , David W. , eds . Ciba Foundation Symposium 24 - Physiological Basis of Starling 's Law of the Heart . John Wiley & Sons , Ltd . pp. 257 -- 290 . doi : 10.1002 / 9780470720066. ch14 . ISBN 9780470720066 . Jump up ^ Hall , John E. ( 2016 ) . Guyton and Hall Textbook of Medical Physiology . Philadelphia : Elsevier . p. 119 . ISBN 9781455770052 . Jump up ^ Bell , P. Darwin ; Peter Komlosi ; Zhi - Ren Zhang ( 2009 ) . `` ATP as a mediator of macula densa cell signalling '' . Purinergic Signalling. 5 ( 4 ) : 461 -- 471 . doi : 10.1007 / s11302 - 009 - 9148 - 0 . ISSN 1573 - 9538 . PMC 2776136 . PMID 19330465 . ^ Jump up to : Komlosi , P. ; A. Fintha ; P.D. Bell ( 2004 ) . `` Current mechanisms of macula densa cell signalling '' . Acta Physiologica Scandinavica. 181 ( 4 ) : 463 -- 469 . doi : 10.1111 / j. 1365 - 201X. 2004.01319. x . ISSN 0001 - 6772 . PMID 15283759 . ^ Jump up to : Jablonka E. ; Lachmann M. ; Lamb M.J. ( 1992 ) . `` Evidence , Mechanisms and Models for the Inheritance of Acquired Characters '' . Journal of Theoretical Biology . 158 ( 2 ) : 245 -- 268 . doi : 10.1016 / s0022 - 5193 ( 05 ) 80722 - 2 . Jump up ^ Lin , Jong - Chin ; Thirumalai , D. ( 2012 - 10 - 25 ) . `` Gene Regulation by Riboswitches with and without Negative Feedback Loop '' . Biophysical Journal . 103 ( 11 ) : 12 . arXiv : 1210.6998 . doi : 10.1016 / j. bpj. 2012.10. 026 . PMC 3514527 . PMID 23283231 . <Th_colspan="2"> ( hide ) Physiology of the cardiovascular system Heart Cardiac output Cardiac cycle Cardiac output Heart rate Stroke volume Stroke volume End - diastolic volume End - systolic volume Afterload Preload Frank -- Starling law Cardiac function curve Venous return curve Wiggers diagram Pressure volume diagram Ultrasound Fractional shortening = ( End - diastolic dimension End - systolic dimension ) / End - diastolic dimension Aortic valve area calculation Ejection fraction Cardiac index Heart rate Cardiac pacemaker Chronotropic ( Heart rate ) Dromotropic ( Conduction velocity ) Inotropic ( Contractility ) Bathmotropic ( Excitability ) Lusitropic ( Relaxation ) Conduction Conduction system Cardiac electrophysiology Action potential cardiac atrial ventricular Effective refractory period Pacemaker potential Electrocardiography P wave PR interval QRS complex QT interval ST segment T wave U wave Hexaxial reference system Chamber pressure Central venous Right atrial ventricular pulmonary artery wedge Left atrial ventricular Aortic Other Ventricular remodeling Vascular system / Hemodynamics Blood flow Compliance Vascular resistance Pulse Perfusion Blood pressure Pulse pressure Systolic Diastolic Mean arterial pressure Jugular venous pressure Portal venous pressure Regulation of BP Baroreflex Kinin -- kallikrein system Renin -- angiotensin system Vasoconstrictors Vasodilators Autoregulation Myogenic mechanism Tubuloglomerular feedback Cerebral autoregulation Paraganglia Aortic body Carotid body Glomus cell Retrieved from `` https://en.wikipedia.org/w/index.php?title=Autoregulation&oldid=827281130 '' Categories : Physiology Talk Contents About Wikipedia Deutsch Eesti Français Galego Italiano Српски / srpski Edit links This page was last edited on 23 February 2018 , at 20 : 29 . About Wikipedia
1. Autoregulation in biological systems
2. Cerebral autoregulation
3. Homeometric and heterometric autoregulation of the heart
4. Coronary circulatory autoregulation
5. Renal autoregulation