98:
performed to evaluate two mechanisms in the kidney, myogenic response and tubuloglomerular feedback. A mathematical model showed good autoregulation through a myogenic response, aimed at maintaining a constant wall tension in each segment of the preglomerular vessels. Tubuloglomerular feedback gave rather poor autoregulation. The myogenic mechanism showed 'descending' resistance changes, starting in the larger arteries, and successively affecting downstream preglomerular vessels at increasing arterial pressures. This finding was supported by micropuncture measurements of pressure in the terminal interlobular arteries. Evidence that the mechanism was myogenic was obtained by exposing the kidney to a subatmospheric pressure of 40 mmHg; this led to an immediate increase in renal resistance, which could not be prevented by denervation or various blocking agents.
107:
263:
that are unstable. It is usually due to ion channels in the cell membrane that spontaneously open and close (e.g. If channels in cardiac pacemaker cells). When the membrane potential reaches depolarization threshold an action potential (AP) is fired, excitation-contraction coupling initiates and the
275:
are unstable resting membrane potentials that continuously cycle through depolarization- and repolarization phases. However, not every cycle reaches depolarization threshold and thus an action potential (AP) will not always fire. Owing to temporal summation (depolarization potentials spaced closely
97:
Myogenic mechanisms in the kidney are part of the autoregulation mechanism which maintains a constant renal blood flow at varying arterial pressure. Concomitant autoregulation of glomerular pressure and filtration indicates regulation of preglomerular resistance. Model and experimental studies were
284:
Pacemaker potentials are unstable cell membrane potentials that reach depolarization threshold with every depolarization/repolarization cycle. This results in AP's being fired according to a set rhythm. Cardiac pacemaker cells, a type of cardiac myocyte in the SA node of heart, are an example of
141:. No action potential is necessary here; the level of entered calcium affects the level of contraction proportionally and causes tonic contraction. The contracted state of the smooth muscle depends on the grade of stretch and plays an important part in the regulation of blood flow.
59:
may be useful in the regulation of organ blood flow and peripheral resistance, as it positions a vessel in a preconstricted state that allows other factors to induce additional constriction or dilation to increase or decrease blood flow.
293:
This mechanism involves the opening of mechanically gated Ca channels when some myocytes are stretched. The resulting influx of Ca ions lead to the initiation of excitation-contraction coupling and thus contraction of the myocyte.
250:
lead to an increased probability in opening of L-type (voltage-dependent) Ca channels, thus raising the cytosolic concentration of Ca leading to a contraction of the myocyte, and this may involve other channels in the endothelia.
241:
fashion. Increase in blood pressure may cause depolarisation of the affected myocytes as well or endothelial cells alone. The mechanism is not yet completely understood, but studies have shown that volume regulated
276:
together in time so that they summate), however, cell membrane depolarization will periodically reach depolarization threshold and an action potential will fire, triggering contraction of the myocyte.
94:) is particularly sensitive to changes in blood pressure. However, with the aid of the myogenic mechanism, the glomerular filtration rate remains very insensitive to changes in human blood pressure.
133:
of the body. When blood pressure is increased in the blood vessels and the blood vessels distend, they react with a constriction; this is the
Bayliss effect. Stretch of the muscle membrane opens a
484:
55:
itself instead of an outside occurrence or stimulus such as nerve innervation. Most often observed in (although not necessarily restricted to) smaller resistance arteries, this 'basal'
485:
Moore L.C., A. Rich, and D. Casellas. Ascending myogenic autoregulation: interactions between tubuloglomerular feedback and myogenic mechanisms.. Bull. Math. Biol. 56:391-410, 1994.
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Betts, J Gordon; Desaix, Peter; Johnson, Eddie; Johnson, Jody E; Korol, Oksana; Kruse, Dean; Poe, Brandon; Wise, James; Womble, Mark D; Young, Kelly A (June 8, 2023).
75:, which reduces blood flow through the blood vessel. Alternatively when the smooth muscle in the blood vessel relaxes, the ion channels close, resulting in
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The overall effect of the myogenic response (Bayliss effect) is to decrease blood flow across a vessel after an increase in blood pressure.
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The importance of the
Bayliss effect in maintaining a constant capillary flow independently of variations in arterial blood pressure
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of an artery is stretched it is likely that the endothelial cell may signal constriction to the muscle cell layer in a
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of the blood vessels reacts to the stretching of the muscle by opening ion channels, which cause the muscle to
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137:. The cells then become depolarized and this results in a Ca signal and triggers
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434:"On the local reactions of the arterial wall to changes of internal pressure"
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This effect is independent of nervous mechanisms, which is controlled by the
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of the blood vessel; this increases the rate of flow through the lumen.
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cells is a response to stretch. This is especially relevant in
344:. Houston: OpenStax CNX. 25.7 Regulation of renal blood flow.
365:
Aukland, K (1989). "Myogenic mechanisms in the kidney".
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The
Bayliss effect was discovered by physiologist Sir
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152:(MAP). This is explained by the following equation:
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125:in the vasculature. The Bayliss effect in vascular
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505:
82:This system is especially significant in the
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43:to keep the blood flow constant within the
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533:
512:
498:
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457:
157:
521:Physiology of the cardiovascular system
330:
393:An introduction to cardiac physiology.
148:(TPR) and this further increases the
90:(the rate of blood filtration by the
7:
246:and stretch sensitive non-selective
144:Increased contraction increases the
39:react to an increase or decrease of
367:Journal of Hypertension Supplement
285:cells with a pacemaker potential.
121:is a special manifestation of the
25:
413:Principals of medical physiology.
233:When the endothelial cell in the
47:. Myogenic response refers to a
450:10.1113/jphysiol.1902.sp000911
432:Bayliss, W. M. (28 May 1902).
1:
648:Aortic valve area calculation
135:stretch-activated ion channel
373:(4): S71–6, discussion S77.
255:Unstable Membrane Potentials
765:Effective refractory period
644:) / End-diastolic dimension
261:resting membrane potentials
146:total peripheral resistance
1120:
208:sympathetic nervous system
192:{\displaystyle MAP=CO*TPR}
88:glomerular filtration rate
1104:Cardiovascular physiology
1050:Tubuloglomerular feedback
997:Critical closing pressure
817:Hexaxial reference system
740:Cardiac electrophysiology
438:The Journal of Physiology
314:Juxtaglomerular apparatus
304:Tubuloglomerular feedback
119:Bayliss myogenic response
1025:Renin–angiotensin system
341:Anatomy & Physiology
1055:Cerebral autoregulation
1020:Kinin–kallikrein system
987:Jugular venous pressure
637:End-diastolic dimension
615:Pressure volume diagram
992:Portal venous pressure
982:Mean arterial pressure
896:Ventricular remodeling
642:End-systolic dimension
600:Cardiac function curve
193:
150:mean arterial pressure
111:
633:Fractional shortening
194:
109:
573:End-diastolic volume
280:Pacemaker potentials
273:Slow-wave potentials
268:Slow wave potentials
156:
937:Vascular resistance
775:Electrocardiography
770:Pacemaker potential
700:Conduction velocity
605:Venous return curve
578:End-systolic volume
264:myocyte contracts.
1045:Myogenic mechanism
663:Left atrial volume
595:Frank–Starling law
229:Proposed mechanism
199:, where CO is the
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139:muscle contraction
112:
29:myogenic mechanism
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744:Action potential
735:Conduction system
681:Cardiac pacemaker
653:Ejection fraction
351:978-1-947172-04-3
244:chloride channels
51:initiated by the
16:(Redirected from
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1030:Vasoconstrictors
1007:Regulation of BP
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853:pulmonary artery
826:Chamber pressure
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714:(Excitability)
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479:External links
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444:(3): 220–231.
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127:smooth muscles
115:Bayliss effect
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102:Bayliss effect
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658:Cardiac index
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568:Stroke volume
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57:myogenic tone
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1072:Carotid body
1044:
1035:Vasodilators
915:hemodynamics
720:(Relaxation)
712:Bathmotropic
686:Chronotropic
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86:, where the
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77:vasodilation
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45:blood vessel
28:
26:
1077:Glomus cell
1067:Aortic body
1062:Paraganglia
873:ventricular
846:ventricular
795:QT interval
790:QRS complex
785:PR interval
758:ventricular
696:Dromotropic
63:The smooth
49:contraction
1015:Baroreflex
932:Compliance
924:Blood flow
800:ST segment
728:Conduction
718:Lusitropic
690:Heart rate
673:Heart rate
625:Ultrasound
556:Heart rate
411:A. Fonyo.
325:References
131:arterioles
69:depolarize
37:arterioles
975:Diastolic
947:Perfusion
706:Inotropic
585:Afterload
239:paracrine
225:in 1902.
178:∗
1098:Category
970:Systolic
748:cardiac
468:16992618
298:See also
33:arteries
18:Myogenic
590:Preload
459:1540533
379:2681599
289:Stretch
217:History
92:nephron
84:kidneys
53:myocyte
31:is how
880:Aortic
868:atrial
841:atrial
837:Right
810:U wave
805:T wave
780:P wave
753:atrial
466:
456:
418:
398:
377:
348:
309:Kidney
65:muscle
942:Pulse
889:Other
864:Left
858:wedge
529:Heart
73:lumen
464:PMID
416:ISBN
396:ISBN
375:PMID
346:ISBN
35:and
27:The
635:= (
454:PMC
446:doi
117:or
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371:7
354:.
187:R
184:P
181:T
175:O
172:C
169:=
166:P
163:A
160:M
20:)
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