消化系統 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Overview of the Digestive Tract The Digestive System Consists of the muscular digestive tract消化管 assisted by various accessory organs附屬器官 Digestive functions include: Ingestion Mechanical processing Digestion Secretion Absorption Excretion Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Overview of the Digestive Tract Digestive Tract Components Oral cavity Pharynx Esophagus食道 Stomach胃 Small intestine小腸 Large intestine大腸 Rectum直腸 Anus肛門 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Overview of the Digestive Tract The Components of the Digestive System and Their Functions Figure 16-1

Overview of the Digestive Tract The Structure of the Digestive Tract 皺襞 腸繫膜 漿膜 黏膜下層 黏膜層 Figure 16-2(a)

Overview of the Digestive Tract The Structure of the Digestive Tract 絨毛 Figure 16-2(b)

Overview of the Digestive Tract Movement of Digestive Materials Involuntary control of smooth muscle of muscularis externa Two kinds of movement Peristalsis蠕動 propels material along the tract Segmentation churns material in the small intestine Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Figure 16-3 1 of 4 Contraction of circular muscles behind food mass Longitudinal muscle Circular muscle From mouth To anus Contraction of longitudinal muscles ahead of food mass Contraction Contraction Contraction of circular muscle layer forces food mass forward Figure 16-3 1 of 4 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

The Oral Cavity Functions of the Oral Cavity Sensory analysis of potential foods Mechanical processing using teeth, tongue, and palate Lubrication of food by mucus in saliva Enzymatic digestion by enzymes in saliva Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

The Oral Cavity Anatomy of the Oral Cavity Also called, buccal cavity Tongue forms floor Hard and soft palate form roof Buccal mucosa forms walls Composed of stratified squamous epithelium Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

The Oral Cavity Functions of the Tongue Mechanical processing of food Manipulation to assist chewing and swallowing Sensory analysis (taste, texture) Participation in speech Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

The Oral Cavity The Oral Cavity 玄雍垂 舌繫帶 Figure 16-4(a)

The Oral Cavity The Oral Cavity Figure 16-4(b)

The Oral Cavity Salivary Glands Three pairs of glands Parotid腮下 Sublingual舌下 Submandibular頷下 Functions of saliva Lubricates, cleanses oral cavity Dissolves chemicals Suppresses bacterial growth Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

The Oral Cavity Teeth Participate in mastication咀嚼 of food Anchored to bone by periodontal ligament牙周韌帶 Dentin象牙質 forms basic shape Enamel琺瑯質 covers crown Cementum牙骨質 covers root 20 deciduous teeth (“baby teeth”) 32 secondary teeth (“adult teeth”) Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

The Oral Cavity Teeth: Structural Components and Dental Succession 牙髓腔 齒冠 齒頸 齒根 根管治療 齒槽骨 Figure 16-6(a)

The Oral Cavity Teeth: Structural Components and Dental Succession 門牙 側門牙 虎牙 Figure 16-6(b)

The Oral Cavity Teeth: Structural Components and Dental Succession Figure 16-6(c)

The Pharynx Functions of the Pharynx Common passageway for food, drink, and air Pharyngeal muscles propel food along esophagus toward the stomach during swallowing Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

The Esophagus Anatomy of the Esophagus Muscular tube about 25 cm long Lined by stratified squamous epithelium Posterior to trachea Penetrates diaphragm at esophageal hiatus裂縫 Possess upper and lower esophageal sphincters括約肌 Sphincter—A circular band of muscle that can pinch close a muscular tube Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

The Esophagus Swallowing (Deglutition)—Three Steps Oral phase Compaction of bolus食丸 Entry into pharynx Pharyngeal phase Elevation of larynx Bending of epiglottis, closing of glottis Esophageal phase Peristalsis pushes bolus toward stomach

The Stomach Functions of the Stomach Temporary storage of ingested food Mechanical breakdown of food Forms chyme食靡, a liquid suspension Breakage of chemical bonds in food by action of acid and enzymes Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

The Anatomy of the Stomach 噴門 胃底 胃體 小彎 腹腔內膜網 大彎 幽門 Figure 16-8(a)

The Phases of Gastric Secretion The Stomach The Phases of Gastric Secretion 頭期 胃期 胃蛋白酶原 胃泌素 小腸期 Figure 16-9

The Small Intestine Regions of the Small Intestine Duodenum十二指長 Jejunum空腸 Ileum結腸 Ileocaecal valve 迴盲瓣 (a sphincter) marks junction with large intestine Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

The Small Intestine The Intestinal Wall Mucosa has transverse folds, plicae circulares Plicae have small projections, villi Both increase surface area of mucosa for absorption Each villus has a lymphatic capillary, a lacteal乳糜管

The Small Intestine The Intestinal Wall 乳糜管 Figure 16-11(b)

The Small Intestine The Intestinal Wall Figure 16-11(c)

The Small Intestine Intestinal Secretions Intestinal glands secrete Intestinal juice小腸液 Moistens chyme Buffers stomach acid Dissolves digestive enzymes Dissolves products of digestion Mucus Hormones Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

The Small Intestine Intestinal Hormones Gastrin Secretin分泌激素 Cholecystokinin (CCK)膽囊收縮素 Gastric Inhibitory Peptide (GIP) Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

The Small Intestine The Activities of Major Digestive Tract Hormones Figure 16-12

The Small Intestine Digestion in the Small Intestine Most enzymatic digestion and absorption occurs in the small intestine Digestive enzymes and buffers are released by: Pancreas胰臟 Liver Gall bladder膽囊 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

The Pancreas Anatomy of the Pancreas Pancreatic duct enters duodenum Duct delivers pancreatic juice Duct branches repeatedly Fine branches end in pancreatic acini腺細胞 Endocrine cells are found among the acini

The Pancreas The Pancreas Figure 16-13(b)

The Pancreas Secretions of the Pancreas Endocrine secretion (hormones) Insulin Glucagon Exocrine secretion (digestive) Water Ions Enzymes Carbohydrases Lipases Proteases Nucleases Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

The Liver Overview of Liver Largest visceral organ Over 200 known functions Four Lobes Right (largest by far) Left Caudate尾 Quadrate正方 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

The Surface Anatomy of the Liver Figure 16-14(b)

The Liver Liver Histology Figure 16-15(a)

The Liver Functions of the Liver Metabolic regulation Store absorbed nutrients, vitamins Release nutrients as needed Hematological regulation Plasma protein production Remove old RBCs Production of bile Required for fat breakdown Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

The Large Intestine Overview of the Large Intestine Reabsorbs water and compacts feces糞便 Absorbs vitamins made by bacteria Stores feces before defecation Consists of three parts Cecum盲腸:Attaches to vermiform appendix闌尾 Colon結腸 Rectum直腸:Terminates in anal canal Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

The Large Intestine The Large Intestine 橫向 下行 上行 結腸袋 迴盲瓣 Figure 16-17(a)

The Large Intestine The Large Intestine Figure 16-17(b)

The Large Intestine Functions of the Large Intestine Absorption Water Ions Vitamins Organic wastes Bile salts Toxins Bacterial growth Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Digestion and Absorption Processing and Absorption of Nutrients Two Steps in Processing Mechanical processing to break down physical structure of foods Chemical processing to break the covalent bonds between food subunits Enzymes catalyze this Activate the hydrolysis of large food molecules Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Digestion and Absorption The Digestion and Absorption of Carbohydrates 澱粉酶 Figure 16-18(a) (1 of 2)

Digestion and Absorption The Digestion and Absorption of Carbohydrates Figure 16-18(a) (2 of 2)

Digestion and Absorption The Digestion and Absorption of Lipids Figure 16-18(b) (1 of 2)

Digestion and Absorption The Digestion and Absorption of Lipids Figure 16-18(b) (2 of 2)

Digestion and Absorption The Digestion and Absorption of Proteins Figure 16-18(c) (1 of 2)

Digestion and Absorption The Digestion and Absorption of Proteins Figure 16-18(c) (2 of 2)

Aging and the Digestive System Age-Related Changes in the Digestive System Thinner, more fragile epithelium Reduced epithelial stem cell division Weaker peristaltic contraction Reduced smooth muscle tone Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings