Spikes0-Depolarization-10Slow20waves-30Stimulationby-401.Norepinephrine-502.Sympathetics60StimulationbyResting1.Stretch-70Hyperpolarization2.Acetylcholine3.Parasympathetics601218243036424854SecondsHall:GuytonandHallTextbookofMedicalrsoloav.12th.EditiotCopyright 2011by Saunders,an imprintof Elsevier.Inc.All rights.The higher the slow wave potential rises, the greater thefrequency of the spikepotentials,thestronger ofthe contraction
The higher the slow wave potential rises, the greater the frequency of the spike potentials, the stronger of the contraction
.Slow wave are undulating? Excited by fairly constant,changes in the restingslow electrical activity thatmembrane potential caused byconsists of 2 types ofthe entry of Nat.electrical activity:Slow waves: The frequency of the slowSpikeswaves sets the rhythm ofcontractions: Note: the resting.However, the slow wavesmembrane potential can bethemselves do not usuallyadjusted. This is important.cause the contractions. Theyasspikesoccuronceadrive the membrane to thresholdthreshold resting membranewhich causes spikes to occur.potential is reached.Spikes cause the contraction
• Excited by fairly constant, slow electrical activity that consists of 2 types of electrical activity: Slow waves Spikes • Note: the resting membrane potential can be adjusted. This is important, as spikes occur once a threshold resting membrane potential is reached. •Slow wave are undulating changes in the resting membrane potential caused by the entry of Na+ . • The frequency of the slow waves sets the rhythm of contractions. • However, the slow waves themselves do not usually cause the contractions. They drive the membrane to threshold, which causes spikes to occur. Spikes cause the contraction
(3) Muscle contractionMechanism of smooth muscle contraction↑CytosolicCat+IntermediatefilamentbundlesattachedtodensebodiesCa+++ CalmodulinCaveolaeActivationofmyosinkinase(a) Relaxed smoothmuscle cellPhosphorylationofmyosinlightchain(b)ContractedsmoothmusclecellActivationofmyosinATPaseCopyright 2006 Pearson Education,Inc.,publishing as Benjamin CummingsFigure9.26AttachmentofmyosinheadwithactinContractionbyslidingfilamentmechanism
(3) Muscle contraction
Ca2+Endoplasmicreticulum92+CalmodulinCa2+Ca-calmodulinMLCKUnphosphorylatedPhosphorylatedmyosinlightmyosin lightchainchainNo myosinMyosinATPaseATPaseactivityactive→No crossbridgeCrossbridgeactivitycyclingSmoothmusclecellContractionO2011PearsonEducation,Inc
Il. Neural control of gastrointestinal function·EntericnervoussystemAutonomicnervous·ExtrinsicnervoussystemcontrolEntericnervouscontrolEndocrinecontrolParacrinecontrolGutcellLuminalcontentscontrol
II. Neural control of gastrointestinal function • Enteric nervous system • Extrinsic nervous system