1、消化系统绪论消化系统绪论An Overview of The Digestive System学习目标学习目标 1001 画图显示消化系统的各器官及其毗邻关系；1002 列举消化系统的主要功能；1003 解释为何消化道是体内最大的内分泌器官和最大的免疫器官；1004 描述消化道血管和神经支配的特点；解释肠神经系统以及肠-脑轴的概念与生理意义；1005 列举消化系统常见疾病的种类，讨论消化系统疾病的临床地位。Organs that constitute the digestive systemOrgans that make up the digestive tract:Mouth Esopha
2、gus Stomach Small Intestine(SI)Large Intestine(colon)Rectum AnusOrgans that help with digestion but are not part of the digestive tract:Tongue Salivary glands Pancreas Liver Gallbladder15 feet(4.6m)Digest foodstuffs;Absorb nutrient molecules Excrete non-nutrients Endocrine DefensePhysiological funct
3、ions of the digestive systemSurface area Skin 1.8 m2;GI mucosae 400 m2Food ingestion Digest foodstuffs;Absorb nutrient molecules Excrete non-nutrients DefenseMain FunctionsMotilitySecretionDigestionAbsorptionImmune reactionsNeurohumoral responsesMajor physiological processesThe responses to food ing
4、estionNausea and vomiting and diarrhea are physiological protective responses to toxic and pathogenic chemicals/microorganisms,but for many can be devastating experiences.Some GI facts Nutrients are broken down by the digestive system and transported to every part of the body by the circulatory syst
5、em.It takes the mouth,esophagus,stomach,small intestine,large intestine,gallbladder,pancreas and liver just to digest a glass of milk.The average male will eat about 50 tons of food during his lifetime.Within the colon,a typical person harbors more than 400 distinct species of bacteria(11.5kg,1014);
6、After you eat,it takes usually between 24 and 72 hours in healthy adults for the complete process of digestion to occur.The liver performs more than 500 functions.Structure&Function(gross anatomy level)Carbohydrates Proteins LipidsMouth(salivary glands)Salivary amylaseLingual lipaseStomachGastricamy
7、lase&gelatinasepepsinGastric lipaseSIDuodenum(pancreas)Pancreatic amylaseTrypsinChymotrypsincarboxypeptidaseLipaseesteraseLining of small intestineAminopeptidasepeptidaselipasePolysaccharidesdisaccharidesdisaccharidesmonosaccharidesLactaseSucraseMaltaseisomaltasepolypeptidesSmall Peptide chainsTripe
8、ptidesDipeptidesAmino acidsMonoglycerridesFree fatty acidsStructure&Function(microscopic level)The splanchnic circulation1)Three major arteries supply oxygen-rich blood to abdominal digestive organs;2)In rest,25%of cardiac output flow through splanchnic circulation;3)Portal vein carries nutrient-ric
9、h blood to the liver;4)Is a reservoir that can be compromised eg,non-occlusive ischemic disease of the gut Innervation1)The extrinsic innervationa.The Parasympathetic Nb.The Sympathetic N2)The intrinsic innervation Also called the Enteric Nervous System(ENS),consisting the submucosal plexus(粘膜下神经丛粘膜
10、下神经丛)&the myenteric plexus(肌肌间神经丛间神经丛),is a complex neuronal network of sensory(afferent)neurons,interneurons&motor(efferent)neurons.3)Dual afferent(sensory)innervationVagal:low threshold;Spinal:wide dynamic range&high thresholdInteroceptors(内感受器内感受器)Gut feelingEntero-endocrine functions(gut hormone
11、s)Stomach Gastrin,Somatostatin,histamine,Ghrelin Duodenum or jejunum Secretin,Cholecystokinin(CCK),Motilin,Somatostatin,Gastric inhibitory peptide,serotonin Pancreatic islets Insulin,Glucagon,Pancreatic polypeptide,Somatostatin Ileum or colon Enteroglucagon,Peptide YY,Neurotensin,Somatostatin,seroto
12、nin(5-HT)Walker AK,Rivera PD,Wang Q,Chuang JC,Tran S,Osborne-Lawrence S,Estill SJ,Starwalt R,Huntington P,Morlock L,Naidoo J,Williams NS,Ready JM,Eisch AJ,Pieper AA,Zigman JM.The P7C3 class of neuroprotective compounds exerts antidepressant efficacy in mice by increasing hippocampal neurogenesis.Mol
13、 Psychiatry.2014 Apr 22.doi:10.1038/mp.2014.34.Grhelin(胃饥饿素胃饥饿素)具有抗抑郁作用具有抗抑郁作用Intestinal flora,pathogens&mucosal immunitya.GIT harbors 5001000 species of microbes;b.GIT is lined by a thin layer of epithelium;c.GIT is the 1st line of defense and the largest immune organ of the body.Immunity.2014 Sep
14、18;41(3):478-92.Clostridium difficile 艰难梭状芽胞杆菌艰难梭状芽胞杆菌22 Sensory input Vagal Spinal Gut hormones 5-HT Leptin CCK GLP-1 .Immune modulation Microbial products Autonomic Nervous Sys.Sympathetic n.Parasympathetic n.Enteric nervous s.HPA axis Descending facilitation or inhibition of GI sensation Regulate
15、 gut immunity Regulate blood flowBottom-up signalsComponents of the Gut-Brain AxisTop down signals The digestive system,which digests foodstuff and absorb nutrients,also constitute the largest endocrine organ&the largest immune organ in the body.The GI tract is equipped with an autonomous nervous sy
16、stem,ie,the enteric nervous system,which plays major role in GI function.Digestion and absorption is an orderly process carried out by the gastrointestinal tract which is regulated(coordinated)by neural and hormonal(neurohumoral)factors.Things can&often go wrong.Diseases of the digestive system acco
17、unt for more hospital admissions than any other category of diseases(USA,how about in China?);Most of us have had at least an episodic experience with the unpleasantness,serious inconvenience and discomfort of a GI disorder;GI dysfunction is often associated with great emotional distress and disabil
18、ity;Many GI diseases can be extremely severe&lethal.Our understanding,diagnosis&management of GI diseases is ever evolving.Diseases of the Digestive System Diseases of the Gastrointestinal Tract Functional Gastrointestinal Tract Diseases(FGIDs)Functional dyspepsia(FD)，Irritable bowel syndrome(IBS),G
19、astroesophageal reflux disease(GERD),non-cardiac chest pain,etc Infection&Inflammationgastritis,enteritis,Crohns disease(CD),ulcerative colitis(UC),etc Ulcer Tumorsesophageal carcinoma,gastric carcinoma,colorectal carcinoma Diseases of the digestive glands Inflammation Hepatitis Pancreatitis Cirrhos
20、is Liver cirrhosis(肝硬化)Tumors Hepatocellular carcinoma,cholangiocarcinoma Pancreatic Carcinoma carcinomaSalmonella colitis.General course objectives 在掌握在掌握消化系统正常结构与功能消化系统正常结构与功能的基础上，的基础上，理解和掌握理解和掌握消化道症状消化道症状和和疾病疾病的的病理表现病理表现和病理生理和病理生理机制、机制、诊断学方法诊断学方法、处理原则处理原则和和药物作用原理药物作用原理。“You are what you eat!”2,08
21、0 Pages3173 pagesAnatomy,Histology&embryology,Physiology,Biochemistry,Pathology,Pathophysiology,Pharmacology,Diagnosis&Management312 pagesCan we achieve the course objectives&your expectations:mission impossible?The core principles(核心原理核心原理)1.1.消化系统各部分的正常组织结构与功能的关系；消化系统各部分的正常组织结构与功能的关系；2.2.消化、吸收和排泄的
22、基本生理过程、机制及神经体液调控消化、吸收和排泄的基本生理过程、机制及神经体液调控原理；原理；3.3.消化道常见疾病（炎症性和功能性疾病及肿瘤等）的症状消化道常见疾病（炎症性和功能性疾病及肿瘤等）的症状与体征、发生机制、病理表现与病理生理过程、诊断学方法与体征、发生机制、病理表现与病理生理过程、诊断学方法以及临床处理原则；以及临床处理原则；4.4.肝功能检查的原理、基本方法以及肝脏疾病时肝脏生化指肝功能检查的原理、基本方法以及肝脏疾病时肝脏生化指标的改变；标的改变；5.5.治疗消化道常见疾病（消化性溃疡、腹痛、腹泻与便秘及治疗消化道常见疾病（消化性溃疡、腹痛、腹泻与便秘及肿瘤）药物的作用原理以
23、及药物对胃肠道的副作用肿瘤）药物的作用原理以及药物对胃肠道的副作用How can we achieve the course objectives&your expectations?We as teachers -Help you to learn!lectures(37 hrs)The core principles navigation(Demo&PBL)-Evaluationmeans,not purpose You as students -Are responsible for the learning process!Active learning:reflection(thin
24、king),question&research(internet,textbooks,etc)Meaningful learning:link what you learn to physiological&clinical scenariosKey messages The digestive system is an important system both in health and in clinical settings;Physiological functions are carried out in GI system in orderly manners regulated
25、 by neurohumoral and immune factors;When things go wrong(which is very common),manifestations can be local or systematic&often devastating;The objectives of this course are for you to learn the“core principles”or the foundations of clinical gastroenterology through active and meaningful learning.Recommended reading
