消化-远程1.ppt

单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,*,概 述,消化（digestion）,是食物在消化道内被分解为小分子物质的过程,吸收（absorption）,消化后的小分子物质以及水、无机盐和维生素，透过消化道粘膜，进入血液和淋巴循环的过程,消化与吸收的基本过程,消化道内食物的推进与混合,消化道的分泌,消化道内的消化与吸收,消化管的结构,消化道平滑肌的一般特性,兴奋性低Low excitability,扩展性好High distensibility,紧张性收缩Tonic contraction,自律性Autorhythmicity,对机械牵张、温度变化和化学刺激敏感High sensitivity to temperature,stretch and chemical stimulation,消化道平滑肌的电生理特性,静息电位,-40-80 mV,离子机制,Em(selective membrane permeability to,K,+,Na,+,Cl,-,and Ca,2+,),Electrogenic Na,+,-K,+,pump,慢波(基本电节律basic electrical rhythm),在静息电位基础上产生自发性去极化和复极化的节律性电位波动，其频率较慢,起源于Cajal细胞 interstitial cells of Cajal(ICC)(pacemaker cell),Santiago Ramon Y Cajal,He and Camillo Golgi received the Nobel Prize in 1906 for introduction of the silver-chromate stain,Calcium imaging in ICC-MY from the guinea-pig antrum.A colocalization procedure was used to identify the Rhod-2 signal from ACK2-Alexa 488 labelled ICC-MY.Panel A shows a stack of 30 sequential optical sections made in the Z optical axis of the ACK2-Alexa 488 signal and the Rhod-2 signal;panels B and C show each signal independently.Panel D shows the stack after the colocalization algorithm was used on each confocal slice,showing that most ICC-MY were well labelled with Rhod-2.It was evident from this experiment that some,but not all,ICC-MY were well-labelled with Rhod-2(see text for more details).The scale bar in panel D is 40 um and it applies to all images,Intracellularly recorded electrical activity from a guinea-pig antral ICC-MY identified with ACK2-Alexa 488.Panel A shows a network of ICC-MY labelled with ACK2-Alexa 488 visualized using fluorescence microscopy,and a single ICC-MY impaled with a LY-filled microelectrode.Panel B shows changes in membrane potential recorded intracellularly from an ICC-MY.One slow wave,marked with the horizontal line in Panel B,is shown in Panel C at an expanded time scale.The scale bar is 15 um.,Cyclic changes in intracellular calcium in ICC-MY in the murine jejunum.Panel A shows a single confocal image with ACK2-Alexa 488 immunore-activity(green)and Rhod-2 labelling(red)taken from a time series.ICC-MY were distinctly labelled with Rhod-2 as shown in panel B.The average fluorescence intensity delineated by the white circled region was measured from images recorded every second,shown in panel C,慢波(基本电节律basic electrical rhythm),幅度:1015 mV,频率:312 cpm,离子机制,Na,+,-K,+,泵的自发性节律性活动,Normal BER frequencies in the gastrointestinal system,动作电位,时程:1020 ms,离子机制:,去极化:Ca,2+,influx,复极化:K,+,efflux,胃肠的神经支配及其作用,内在神经系统(intrinsic),自主神经系统(extrinsic),内在神经系统,肌间神经丛,Myenteric plexus(Auerbachs plexus),粘膜下神经丛,Submucosal plexus(Meissners plexus),内在神经元分泌的神经递质,Ach,NE,ATP,serotonin,dopamine,cholecystokinin,substance P,vasoactive intestinal polypeptide,somatostatin,leu-enkephalin,met-enkephalin,bombesin,etc.,交感神经,NE,Inhibitory(-),自主神经系统,副交感神经,Mainly,ACh,Stimulatory(+),从胃肠道来的传入性感觉神经纤维,Sensory fibers with their cell bodies in the ENS terminate in the ENS,Sensory fibers with their cell bodies in the ENS send axons upward through the ANS to terminate in the prevertebral sympathetic ganglia,Sensory fibers with their cell bodies in the dorsal root ganglia or in the cranial nerve ganglia send axons to multiple area of the spinal cord or brain stem,胃肠反射,三种类型,Reflexes that are integrated entirely within the enteric nervous system,Reflexes from the gut to the prevertebral sympathetic ganglia and then back to the gastrointestinal tract,Reflexes from the gut to the spinal cord or brain stem and then back to the gastrointestinal tract,胃肠激素,胃肠激素胃肠道内分泌细胞合成和释放的生物活性化学物质,作用,调节消化腺的分泌和消化道的运动,调节其他激素释放,营养作用,胃肠激素,四种主要类型,胃泌素 Gastrin,促胰液素 Secretin,胆囊收缩素 Cholecystokinin(CCK),抑胃肽 Gastric inhibitory peptide(GIP),内脏循环Splanchnic circulation,Blood supply to the intestines through the mesenteric web,Microvasculature of the intestinal villus,胃内消化Digestion in the stomach,胃液Gastric juice,性质,pH 0.91.5,1.52.5 L/day,主要成分,盐酸 Hydrochloric acid,胃蛋白酶原 Pepsinogen,粘液 Mucus,内因子 Intrinsic factor,盐酸Hydrochloric acid,由胃底腺中的壁细胞（parietal cell）分泌,分泌量,Basal:05 mmol/h,Maximal:2025 mmol/h,分泌机制,主动转运Active transport,Huge H,+,gradient(3 million),盐酸的作用,杀灭随食物进入胃内的细菌,激活胃蛋白酶原，提供必要的酸性环境,引起促胰液素的释放,有利于铁和钙在小肠内吸收,胃蛋白酶原 Pepsinogen,MW:42,500,由胃底腺的主细胞（chief cell）分泌,在盐酸作用下，或在酸性条件下，通过自身催化转变为有活性的胃蛋白酶（pepsin）,Active,pepsin,(MW:35,000),作用,Proteins,Proteoses,Peptones,Polypeptides,Pepsin,粘液 Mucus,由表面上皮细胞、胃底腺的颈粘液细胞、贲门腺和幽门腺共同分泌,作用,润滑,减少粗糙食物对胃粘膜的机械性损伤,Mucus-HCO,3,-,barrier,内因子 Intrinsic factor,分子量约6万的糖蛋白,由壁细胞分泌,促进维生素B12的吸收,其他酶的分泌,Gastric lipase,Gastric amylase,Gelatinase,胃液分泌的调节,引起胃液分泌的因素,乙酰胆碱Acetylcholine(,+,all secretory cells),胃泌素Gastrin(,+,parietal cells),组胺Histamine(,+,parietal cells),胃液分泌的调节,神经调节Nervous regulation,短反射途径Short reflex pathways,Short excitatory reflexes:mediated by cholinergic neurons in the plexuses,Short inhibitory reflexes:mediated by non-adrenergic non-cholinergic(NANC)neurons,胃液分泌的调节,神经调节,长自主神经途径Long autonomic pathways,Long excitatory reflexes:parasympathetic,Long inhibitory pathways:sympathetic,胃液分泌的调节,激素调节,Excitatory,ACh,Histamine,Gastrin,Inhibitory,Somatostatin,Secretin,5-hydroxytryptamine(5-HT),Prostaglandin,消化期的胃液分泌,头期Cephalic phase,胃期Gastric phase,肠期Intestinal phase,胃液分泌的抑制,盐酸,脂肪,高张溶液,胃的运动Motor function of the stomach,Proximal stomach,cardia,fundus,corpus,(body),Distal stomach,antrum,pylorus,pyloric sphincter,胃运动的主要形式,容受性舒张,Receptive relaxation,当咀嚼和吞咽时，食物对咽、食管等处感受器的刺激可引起胃头区肌肉的舒张,Storage function(1.01.5 L),Vago-vagal reflex,蠕动,Peristalsis,BER in the stomach,Contractions in the empty stomach,Migrating Motor Complex(MMC),Periodic waves of contraction,which move along the gastrointestinal tract from stomach to colon,Purpose of this activity:to sweep debris out of the digestive tract during the interdigestive period,MMCs can lead to hunger contractions,which are associated with discomfort,referred to as hunger pains,胃的排空Emptying of the stomach,胃内食糜由胃排入十二指肠的过程称为胃排空（gastric emptying）,Emptying rate,Fluid viscous,Small particle large particle,Isosmotic hyper-&hypo-osmotic,Carbohydrates Protein Fat,Regular meal 46 hrs,胃排空的调节,Gastric factors that promote emptying,Gastric food volume,Gastrin,Duodenal factors that inhibit stomach emptying,Enterogastric nervous reflexes,Fat,Cholecystokinin,呕吐Vomiting,