浙江大学医学院：人体消化系统（PPT课件讲稿）食物的吸收 Absorption

食物的吸收 Absorption 夏强,PhD 浙江大学医学院生理学系 医学院科研楼C座518室 电话:88206417,88208252 Email:xiaqiang@zju.edu.cn

食物的吸收 Absorption 夏 强，PhD 浙江大学医学院生理学系 医学院科研楼C座518室 电话：88206417, 88208252 Email：xiaqiang@zju.edu.cn

学习目标 了解人体消化系统与吸收有关的结构 能比较消化道对各类营养物质的吸收形式 和机制 能应用消化道吸收知识明确促进与抑制 种菅养物质吸收的作用靶点

学习目标 • 了解人体消化系统与吸收有关的结构 • 能比较消化道对各类营养物质的吸收形式 和机制 • 能应用消化道吸收知识明确促进与抑制一 种营养物质吸收的作用靶点

Copyright@ The McGraw-Hill Companies, Inc. Permission required for reproduction or display Blood flo Hepatic ++++ portal vein Absorption Secretion Mouth Food and water 鸟知:mn9 Feces Esophagus Rectum Small intestine Stomach Colon Motility 消化道四大过程 digestion, secretion, absorption and motility

消化道四大过程: digestion, secretion, absorption, and motility

Food 2.0 L/day Saliva 1.5 L/day 1.5 L/day 消化道的液体平衡 Digestive secretions are mostly water 1 L/day Presented to lumen HCOS) with the average of small intestine 8.5 L/day amounts indicated here. Note that only Proximal Presented to colon: 100 ml are excreted by colon in feces. so the by colon 1.9 L/day mechanisms for water absorption are efficient (recall the kidneys primary role in water and Excreted osmotic homeostasis

消化道的液体平衡 Digestive secretions are mostly water, with the average amounts indicated here. Note that only 100 ml are excreted in feces, so the mechanisms for water absorption are efficient (recall the kidneys’ primary role in water and osmotic homeostasis)

Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display Lumen of gastrointestinal tract Endocrine cells Mucous cells Epithelium Exocrine cells Lamina Mucosa Muscularis major blood and Submucosa lymphatic vessels Submucosal nerve plexus Muscularis muscle externa Myenteric Longitudinal Ducts from external exocrine Abdominal cavity glands(liver, pancreas 消化道与吸收有关的结构 The gut wall has a layered organization, with the absorptive cells lining the lumen and neural and muscular components below. blood and lymph vasculature is abundant to transport absorbed nutrients

消化道与吸收有关的结构 The gut wall has a layered organization, with the absorptive cells lining the lumen and neural and muscular components below. Blood and lymph vasculature is abundant to transport absorbed nutrients

Lumen Villus Epithelial cells nutrients Microvilli- 与吸收有关的结构 Capillaries By projecting Nerve E fiber into the lumen Arteriole venule 2 the villi increases the surface area Lacteal for absorption of TyRes nutrients Microvilli [aka brush border] fringe the villi to further increase Lymph duct Vein Muscularis Artery mucosae surface area

与吸收有关的结构 By projecting into the lumen, the villi increases the surface area for absorption of nutrients. Microvilli [aka brush border] fringe the villi to further increase surface area. nutrients

Lumen Epithelium Interstitial space DIGESTION EXAMPLE None Glucose Glucose Luminal hydrolysis of0-=。0→。 polymer to monomers roteIn Amino acids (AA) ○◇ Sucrose Brushborder hydrolysis of oligomer to monomer Glucose Glucose Fructose Fructose Intracellular hydrolysis =o= pti Luminal hydrolysis Glycerol followed by intracellular resynthesis Triacylglycerol B3- Triacylglycerol 消化与吸收的一般机制 General mechanisms of digestion and absorption

消化与吸收的一般机制 General mechanisms of digestion and absorption

A CARBOHYDRATES, PROTEINS AND LIPIDS B CALCIUM IRON AND FOLATE Calcium Iron Carbo- Du odeum Folate Duodenum hydrates, Jej unum Calcium proteins, ← Calcium High absorption Moderate absorption C BILE ACIDS D COBALAMIN Low absorption Very low absorption Duodenum Bile Jejunum Cobalamin 营养物质的吸收部位 Sites of nutrient absorption

营养物质的吸收部位 Sites of nutrient absorption

主要消化道疾病与营养缺乏 Major gastrointestinal diseases and nutritional deficiencies Organ Site of Defects in Nutrient Disease Predominant Disease Digestion/Absorption Celiac sprue(脂肪痢) Duodenum and jejunum Fat absorption lactose hydrolysis Chronic pancreatitis(慢性 胰腺炎) EXocrine pancreas Fat digestion Surgical resection of ileum (回肠手术切除) Crohn disease of ileum(Bleum Cobalamin and bile acid absorption 肠 Crohn氏病) Primary lactase deficiency (原发性乳糖酶缺乏) Small intestine Lactose hydrolysis

主要消化道疾病与营养缺乏 Major gastrointestinal diseases and nutritional deficiencies Disease Organ Site of Predominant Disease Defects in Nutrient Digestion/Absorption Celiac sprue（脂肪痢） Duodenum and jejunum Fat absorption, lactose hydrolysis Chronic pancreatitis（慢性 胰腺炎） Exocrine pancreas Fat digestion Surgical resection of ileum （回肠手术切除） Crohn disease of ileum（回 肠Crohn氏病） Ileum Cobalamin and bile acid absorption Primary lactase deficiency （原发性乳糖酶缺乏） Small intestine Lactose hydrolysis

umen Epithelium Interstitial space 糖的吸收 A DIGESTION OF STARCH IN LUMEN B DIGESTION OF OLIGOSACCHARIDES AT BRUSH BORDER Carbohydrates Lumen toplasm a-Amylase Lactase Lactase splits lactose Both monomers are Amylopectin ansported via SGLTI bb△ Lactose The three monosaccharide SGLT1 Terminal Adjacent a-1,6 linkage Adjacent Terminal products of carbohydrate a-14 link a-1,4 link(branching)a-1A link a-1.link Glucoamylase (also known as maltase) digestion- glucose, galactose Cannot be at removes glucose 2 Na. by amylase by amylase monomers for transport and fructose-are absorbed by the small intestine in a two-step process(两步机制) involving bb.b √bb bbb their uptake across the apical Maltotriose a-Limit dextr Maltotriose ol maltose membrane into the epithelial cell wb Sucrase-isomaltase is actually SGLT1 and their coordinated exit across Maltose the basolateral membrane splits sucrose, as well as maltose and maltotriose 2 Nae GLUT5 The Na/glucose transporter 1 C ABSORPTION OF MONOSACCHARIDES (SGLT1)is the membrane protein Sucrase-isomaltase responsible for glucose and SGLT1 o Sucrose galactose uptake at the apical Galactose○ G| ucose○ ③ O Maltose membrane. the exit of all three b Glucoseo 2 Na( GLUT2 O monosaccharides across the ◆2K basolateral membrane uses a GLUT2 O SGLT facilitated sugar transporter GLUT5 b Fructose (GLUT2) O Maltose Maltotriose The isomaltase moiety splits a-limit dextrins, as wellas

糖的吸收 Carbohydrates The three monosaccharide products of carbohydrate digestion— glucose, galactose, and fructose—are absorbed by the small intestine in a two-step process（两步机制）involving their uptake across the apical membrane into the epithelial cell and their coordinated exit across the basolateralmembrane. The Na/glucose transporter 1 (SGLT1) is the membrane protein responsible for glucose and galactoseuptake at the apical membrane. The exit of all three monosaccharides across the basolateralmembrane uses a facilitated sugar transporter (GLUT2)