消化系统组成

消化管DigestiveTract概述（一）消化系统组成消化管：口、咽、食管、胃、小肠、大肠、肛门消化腺小消化腺：散布于消化管壁内大消化腺：唾液腺、胰、肝（二）功能1、消化食物2、吸收营养3、排泄食物残渣4、防御作用消化管的组成：口腔咽食管胃小肠大肠肛门一、消化管一般结构管壁分四层：黏膜、黏膜下层、肌层、外膜（一）黏膜（tunicamucosa）1、上皮：单柱为主，上、下端为复扁2、固有层：由富含淋巴组织和免疫细胞的结缔组织组成3、粘膜肌：一般为内环、外纵肌（二）黏膜下层（submucosa）L.C.T.，含小A、小V、淋巴管、黏膜下神经丛食管与十二指肠的黏膜下层含有食管腺和十二指肠腺*皱襞(plica)：消化管黏膜与黏膜下层共同向管腔内突起，扩大黏膜面积小肠肌间神经丛 HE染色 高倍 n神经元胞体（三）肌层(tunicamuscularis)主要为平滑肌，上、下端为骨骼肌（四）外膜（adventitia）消化管壁的最外层，按其组成的不同可分两种纤维膜：仅由C.T组成(食管和大肠末段)浆膜：薄层C.T间皮组成(胃肠)二、食管(esophagus)1.黏膜(mucosa)（1）上皮(epithelium)：未角化复扁（2）固有层：细密结缔组织（3）黏膜肌：纵行平滑肌束2.黏膜下层：LCT，食管腺3.肌层：上1/3骨骼肌，中1/3骨骼肌+平滑肌下1/3平滑肌4.外膜：纤维膜食管横切面食管HE切片：示黏膜及黏膜下层Barrett Esophagus is a chronic complication of gastroesophageal reflux disease(GERD),characterized by metaplasia of the stratified squamous epithelium of the lower esophagus into a specialized glandular epithelium with goblet cells.And the inflammatory cells(mainly lymphocytes and plasma cells)are infiltrating the connective tissue.三、胃(stomach)胃分贲门、胃底和胃体、幽门四部分胃壁四层结构：黏膜；黏膜下层；肌层；外膜胃底与胃体部立体模式图(一)黏膜胃空虚时可见许多纵行皱襞，充盈时皱襞消失黏膜表面还布满约350万个小孔，称胃小凹，每个胃小凹底有17条腺体通连1.上皮：形态：a.单层柱状，表面黏液细胞为主b.椭圆形核位于基部c.顶部胞质充满黏原颗粒，HE标本上着色浅淡d.相邻细胞近游离面形成紧密连接功能：分泌黏液样物质，分布于黏膜表面，形成一层保护层胃腺贲门腺：位于贲门幽门腺：位于幽门胃底腺：胃底胃体均为黏液腺颈部：与胃小凹底相连体部：较长位于腺中部底部：略膨大，可达黏膜肌2、固有层充满腺体胃底腺(fundicgland)：分支管状腺组成：主细胞、壁细胞、颈黏液细胞、干细胞和内分泌细胞1）壁细胞（parietalcell）部位：胃底腺上半部结构：LM：细胞大，胞质红，可有双核EM：线粒体丰富微管泡系统细胞内分泌小管微绒毛功能：合成HCl杀菌，激活胃蛋白酶分泌内因子帮助VitB12吸收壁细胞电镜图 nL.胃底腺腔nM.线粒体nMV.微绒毛nC.细胞内分泌小管壁细胞电镜特点：细胞内小管(intracellularsecretorycanalicudus)微管泡系统(tubulovesicularsystem)线粒体丰富2）主细胞部位：胃腺底部形态：LM：柱状，胞质嗜碱性EM：丰富的RER，发达的高尔基复合体，顶部有酶原颗粒。功能：分泌胃蛋白酶原胃主细胞电镜图 2.固有层胃底腺3）颈粘液细胞4）未分化细胞5）内分泌细胞3.黏膜肌平滑肌二、黏膜下层：LCT三、肌层：很厚的平滑肌(内斜、中环、外纵)四、外膜：浆膜Gastric Ulcer(Peptic Ulcer)are chronic mucosal lesions that occur in the gastro-intestinal tract.Morphologically,peptic ulcers are usually small,round to oval in shape,less than 4 cm in diameter with well defined margins without elevation,and have a clean,smooth base.This image shows the transition from gastric mucosa to ulcer,showing a fibrinopurulent surface with underlying granulation tissue.The gastric mucosa shows chronic gastritis with plasma cells within the lamina propria and intestinal metaplasia(note the goblet cells).Gastric Ulcer(Peptic Ulcer)are chronic mucosal lesions that occur in the gastro-intestinal tract.Morphologically,peptic ulcers are usually small,round to oval in shape,less than 4 cm in diameter with well-defi ned margins without elevation,and have a clean,smooth base.Histologically,a thin layer of necrotic fi brinoid debris with neutrophil infi ltration is seen,beneath which lies granulation tis-sue.Treatments include using H2 receptor antagonists;antibiotics;proton pump inhibitors;and surgery for severe,refractory cases.Care must be taken to differentiate benign ulcers from malignant adenocarcinomas,which may appear ulcerated.This image shows the transition from gastric mucosa to ulcer,showing a fi brinopuru-lent surface with underlying granulation tissue.The gastric mucosa shows chronic gastritis with plasma cells within the lamina propria and intestinal metaplasia(note the goblet cells).Figure 15-8C.Gastrinoma(Zollinger-Ellison Syndrome).H&四、小肠(smallintestine)十二指肠十二指肠空肠空肠回肠回肠四、小肠(smallintestine)小肠壁四层结构：皱襞(plica):黏膜和黏膜下层向肠腔面形成的突起绒毛(villus):上皮和固有层向肠腔面形成的突起微绒毛(microvillia):细胞膜和细胞质向肠腔面形成的突起（一）黏膜空肠黏膜 示小肠绒毛 HE染色 低倍 图13-18 十二指肠绒毛扫描电镜图 图13-19 十二指肠模式图1、上皮：单层柱状，由吸收细胞、杯状细胞和内分泌细胞组成1）吸收细胞：数量较多LM：a细胞高柱状，核卵圆形，位于细胞基部b细胞游离面有纹状缘，即EM下的微绒毛EM：a密集的微绒毛b微绒毛表面有一层细胞衣c微绒毛的膜上有特殊受体，有利于物质吸收d丰富的滑面内质网e侧面连接复合体图13-20小肠绒毛 HE染色 高倍 n*中央乳糜管2）杯状细胞：散在于吸收细胞之间，分泌黏液，有润滑和保护作用。从十二指肠至回肠末端，杯状细胞逐渐增多营养物质的消化吸收：淀粉酶双糖酶受体淀粉双糖单糖吸收细胞内血液蛋白水解酶氨基肽酶受体蛋白质多肽氨基酸吸收细胞内血液脂肪酶脂肪甘油一酯+脂肪酸甘油三酯(吸收细胞内)中央乳靡管血液2、固有层:细密结缔组织,中央乳糜管,小肠腺中央乳糜管：绒毛中轴固有层内的纵行毛细淋巴管，利于脂类物质吸收。小肠绒毛 HE染色 高倍 n*中央乳糜管小肠腺:柱状细胞,杯状细胞,内分泌细胞,未分化细胞,潘氏细胞潘氏细胞(Penethcell):腺底部,锥体型,胞质内含嗜酸性颗粒,能分泌溶菌酶2、固有层4）淋巴组织十二指肠：弥散淋巴组织空肠：孤立淋巴结回肠：集合淋巴小结3、黏膜肌内环外纵平滑肌十二指十二指肠肠空肠空肠回肠回肠二、黏膜下层：L.C.T.；含小A.小V；有粘膜下神经丛；十二指肠有十二指肠腺。三、肌层：内环、外纵平滑肌有肌间神经丛四、外膜：多为浆膜，十二指肠为纤维膜Peptic Duodenitis is an inflammatory process caused by chronic exposure of the duodenal mucosa to increased levels of gastric acid and is usually found in the first portion of the duodenum,the duodenal bulb.This photomicrograph shows duodenal mucosa with complete replacement of the normal epithelium with goblet cells by gastric foveolar epithelium.Note the widened,distorted villi and increased inflammatory cells within the lamina propria.Figure 15-10C.Peptic Duodenitis.H&E,48Peptic duodenitis is an infl ammatory process caused by chronic exposure of the duodenal mucosa to increased levels of gastric acid and is usually found in the fi rst portion of the duodenum,the duodenal bulb.Symptoms of peptic duodenitis include epigastric pain and dyspepsia.Histologic features include flattening,or blunting,of the normally fi ngerlike villi,increased inflammatory cells within the lamina propria,Brunner gland hyperplasia,crypt hyperplasia,and gastric foveolar metaplasia of the epithelium.Metaplasia to a gastric foveolar type of epithelium is an adaptive protective response to the increased levels of acid.H.pylori may be found in the metaplastic mucosa as seen in the stomach.In time,a duodenal ulcer may result from peptic duodenitis.This photomicrograph shows duodenal mucosa with complete replace-ment of the normal epithelium with goblet cells by gastric foveo-lar epithelium.Note the widened,distorted villi and increased infl ammatory cells within the lamina propria.（一）结肠：特点：1）黏膜无绒毛2）上皮为单层柱状，杯状细胞多3）固有层有大肠腺长而发达，由吸收细胞、杯状细胞、内分泌细胞和未分化细胞组成，无潘氏细胞；4）外纵肌局部增厚形成三条粗的结肠带五、大肠大肠分盲肠、阑尾、结肠和直肠直肠肛门交界处（二）阑尾特点：肠腺短而少；淋巴组织多，黏膜肌不完整六、肠相关淋巴组织及其免疫功能消化管的淋巴组织包括弥散的淋巴组织（淋巴细胞、浆细胞、巨噬细胞）、孤立和集合淋巴小结，统称为肠相关淋巴组织（GALT）nMC微皱褶细胞nPC浆细胞七、胃肠道内分泌细胞位置：散在于胃肠上皮和腺体内形状：圆锥形或椭圆形，基底部附于基膜上类型：O.开放型/C.封闭型Colorectal Cancer is a malignant neoplasm of the colon or the rectum.Adenocarcinoma is the most common type of colon cancer(98%of cases.Presenting symptoms may be a change in bowel habits due to bowel obstruction,blood in the stool,or iron deficiency anemia.This photomicrograph shows a moderately differentiated adenocarcinoma of the colon infiltrating the muscularis propria.Figure 15-18B.Colorectal Cancer.H&E,97Colorectal cancer is a malignant neoplasm of the colon or the rectum.Risk factors include genetics,infl ammatory bowel diseaseespecially ulcerative colitisadenomatous polyps,high-fat and low-fi ber diets,and excessive red meat consump-tion.Adenocarcinoma is the most common type of colon cancer(98%of cases),arising from the mucosal glandular epithelium,often in adenomatous polyps.Colorectal carcinomas invade through the layers of the intestinal wall and metastasize pre-dominantly through the lymphatic system.Depending on the location,colorectal cancers may be asymptomatic for years.Presenting symptoms may be a change in bowel habits due to bowel obstruction,blood in the stool,or iron defi ciency ane-mia.Surgical resection is the fi rst choice for early-stage cancer,although chemotherapy may be considered.This photomicro-graph shows a moderately differentiated adenocarcinoma of the colon infi ltrating the muscularis propria.Crohn Diseaseis a chronic autoimmune inflammatory disease of the gastrointestinal tract that may affect any location,from the oral cavity to the anus,but mostly involves the distal small intestine and colon.This image shows colonic mucosa with depletion of goblet cells,noncaseating granulomas within the lamina propria,chronic inflammation,and neutrophils invading the crypt cells.Figure 15-20B.Crohn Disease.H&E,97Crohn disease is a chronic autoimmune infl ammatory disease of the gastrointestinal tract that may affect any location,from the oral cavity to the anus,but mostly involves the distal small intestine and colon.Crohn disease is characterized by asymmetric and segmental infl ammation extending through the intestinal wall(transmural)from the mucosa to the serosa.Crohn disease characteristically involves areas of the bowel separated by intervening uninvolved areas or“skip”lesions.Symptoms include abdominal pain,diarrhea,vom-iting,and weight loss.Pathologic changes include mucosal neutrophil and mononuclear cell infi ltration,ulceration,mucosal fi ssures,fi stulae,serosal adhesions,abscesses,pseu-dopolyps,and noncaseating granulomas.Treatment focuses on relieving symptoms through immunosuppressive agents to prevent relapse and complications.This image shows colonic mucosa with depletion of goblet cells,noncaseating granulomas within the lamina propria,chronic infl amma-tion,and neutrophils invading the crypt cells.消化管各段黏膜层比较消化管各段黏膜层比较名词解释：壁细胞，主细胞，小肠绒毛，中央乳糜管问答题：1、试述小肠黏膜结构特点及其与功能的关系。2、比较胃和小肠黏膜结构的异同。习题：掌握：1、掌握消化管一般结构2、掌握胃及小肠黏膜层的结构及其与功能的关系3、掌握大肠壁的结构特点三、小肠黏膜层的结构及功能1、增大肠腔面积：皱襞，绒毛，微绒毛2、上皮：单层柱状上皮吸收细胞（消化吸收）杯状细胞（分泌黏液保护）3、固有层丰富毛细血管（吸收）中央乳糜管（吸收）小肠腺（防御）淋巴组织（保护）4、黏膜肌调节腺体分泌及血液运行