Pharynx (throat) Salivary Oral cavity glands (mouth) Esophagus Stomach Fig. 16.1 Copyright © McGraw-Hill Education. Permission required for reproduction or display. Pharynx (throat) Oral cavity (mouth) Salivary glands Esophagus Stomach Pancreas Small intestine Liver Large intestine Gallbladder Appendix Rectum Anus

Fatty acids Mono- glycerides Amino acids Fig. 16.22 Copyright © McGraw-Hill Education. Permission required for reproduction or display. Food Carbohydrates Lipids Proteins Fatty acids Mono- glycerides Amino acids Monosaccharides

Fig. 16.23 Copyright © McGraw-Hill Education. Permission required for reproduction or display. Carbohydrates Lipids Proteins Mouth (salivary glands) Salivary amylase Polysaccharides, Disaccharides Stomach Pepsin Polypeptides Duodenum (pancreas, liver) Bile salts (liver) Trypsin, chymotrypsin, carboxypeptidase (pancreas) Pancreatic amylase Lipase (pancreas) Disaccharides Peptides Epithelium of small intestine Disaccharidases Peptidases Monosaccharides Fatty acids Monoglycerides Amino acids

Pharynx (throat) Salivary Oral cavity glands (mouth) Esophagus Stomach Fig. 16.1 Copyright © McGraw-Hill Education. Permission required for reproduction or display. Pharynx (throat) Oral cavity (mouth) Salivary glands Esophagus Stomach Pancreas Small intestine Liver Large intestine Gallbladder Appendix Rectum Anus

Fig. 16.2 Blood vessels Myenteric plexus Lymphatic vessel Enteric Copyright © McGraw-Hill Education. Permission required for reproduction or display. Blood vessels Myenteric plexus Lymphatic vessel Enteric plexus Submucosal plexus Nerve Gland in submucosa Mesentery Ducts from glands Lymphatic nodule Intestinal gland Mucosa (mucous membrane) Submucosa Muscularis Circular muscle layer Longitudinal Serosa (serous membrane; visceral peritoneum) Epithelium Lamina propria Connective tissue layer Muscularis mucosae Simple squamous epithelium

Table 7.2

Table 4.10b

A wave of smooth muscle relaxation moves Fig. 16.9 Copyright © McGraw-Hill Education. Permission required for reproduction or display. Digestive tract Bolus 1 Wave of relaxation 1 A wave of smooth muscle relaxation moves ahead of the bolus, allowing the digestive tract to expand. 2 A wave of contraction of the smooth muscle behind the bolus propels it through the digestive tract. Bolus moves. 2 Wave of contraction

A secretion introduced into the digestive tract or into food within Fig. 16.15 Copyright © McGraw-Hill Education. Permission required for reproduction or display. 1 A secretion introduced into the digestive tract or into food within the tract begins in one location. Secretion or food 1 2 Segments of the digestive tract alternate between contraction and relaxation. Contraction waves 2 3 Material (brown) in the intestine is spread out in both directions from the site of introduction. 3 4 Contraction waves 4 The secretion or food is spread out in the digestive tract and becomes more diffuse (lighter color) through time.

Fig. 16.2 Blood vessels Myenteric plexus Lymphatic vessel Enteric Copyright © McGraw-Hill Education. Permission required for reproduction or display. Blood vessels Myenteric plexus Lymphatic vessel Enteric plexus Submucosal plexus Nerve Gland in submucosa Mesentery Ducts from glands Lymphatic nodule Intestinal gland Mucosa (mucous membrane) Submucosa Muscularis Circular muscle layer Longitudinal Serosa (serous membrane; visceral peritoneum) Epithelium Lamina propria Connective tissue layer Muscularis mucosae Simple squamous epithelium

Fig. 16.4 Upper lip Gingiva covering the maxillary alveolar process Copyright © McGraw-Hill Education. Permission required for reproduction or display. Hard palate Soft palate Uvula Cheek Molars Premolars Canine Incisors Upper lip Tongue Frenulum of the tongue Lower lip Gingiva covering the maxillary alveolar process Openings of the submandibular ducts mandibular alveolar

Parotid duct Buccinator muscle Mucous membrane (cut) Ducts of the Fig. 16.7 Copyright © McGraw-Hill Education. Permission required for reproduction or display. Buccinator muscle Mucous membrane (cut) Ducts of the sublingual gland Sublingual gland Submandibular duct Parotid Masseter Parotid duct

During the voluntary phase, a bolus of food Fig. 16.8-1 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Tongue Hard palate Soft palate 1 Bolus Oropharynx 1 During the voluntary phase, a bolus of food (yellow) is pushed by the tongue against the hard and soft palates and posteriorly toward the oropharynx (blue arrow indicates tongue movement; black arrow indicates movement of the bolus). Tan: bone; purple: cartilage; red: muscle.

Fig. 16.8 Copyright © McGraw-Hill Education. Permission required for reproduction or display. Tongue Hard palate Soft palate Nasopharynx 1 Soft palate 2 Superior pharyngeal constrictor Middle pharyngeal constrictor Bolus Epiglottis Oropharynx Inferior pharyngeal constrictor Larynx Upper esophageal sphincter Esophagus 1 During the voluntary phase, a bolus of food (yellow) is pushed by the tongue against the hard and soft palates and posteriorly toward the oropharynx (blue arrow indicates tongue movement; black arrow indicates movement of the bolus). Tan: bone; purple: cartilage; red: muscle. 2 During the pharyngeal phase, the soft palate is elevated, closing off the nasopharynx. The pharynx and larynx are elevated (blue arrows indicate muscle movement; green arrow indicates elevation of the larynx). 3 3 Epiglottis Superior pharyngeal constrictor Middle pharyngeal constrictor Opening of larynx Vestibular fold Vocal fold 3 Successive constriction of the pharyngeal constrictors from superior to inferior (blue arrows) forces the bolus through the pharynx and into the esophagus. As this occurs, the vestibular and vocal folds expand medially to close the passage of the larynx. The epiglottis (green arrow) is bent down over the opening of the larynx largely by the force of the bolus pressing against it. Inferior pharyngeal constrictor Upper esophageal sphincter 4 5 Esophagus Esophagus 4 As the inferior pharyngeal constrictor contracts, the upper esophageal sphincter relaxes (outwardly directed blue arrows), allowing the bolus to enter the esophagus. 5 During the esophageal phase, the bolus is moved by peristaltic contractions of the esophagus toward the stomach (inwardly directed blue arrows).

Fig. 16.10 Copyright © McGraw-Hill Education. Permission required for reproduction or display. Esophagus Fundus Location of lower esophageal sphincter Body Gastroesophageal opening Serosa Cardiac part Longitudinal muscle layer Circular muscle layer Muscularis Oblique muscle layer Pyloric sphincter Submucosa Pyloric orifice Mucosa Pyloric part Pyloric canal Pyloric antrum Duodenum Rugae Gastric pit Surface mucous cell Lamina propria Gastric glands Goblet cell Mucous neck cells Surface mucous cell Parietal cells Mucosa Mucous neck cell Gastric pit Chief cells Endocrine cells Submucosa Blood vessels Oblique muscle layer Muscularis Circular muscle layer Longitudinal muscle layer Connective tissue layer Simple Serosa (visceral peritoneum) squamous epithelium LM 30x ©Victor Eroschenko

Fig. 16.11 Copyright © McGraw-Hill Education. Permission required for reproduction or display. Cephalic Phase 1 The taste, smell, or thought of food or tactile sensations of food in the mouth stimulate the medulla oblongata (green arrows). Taste, smell, or thought of food (chemoreceptors) 2 Vagus nerves carry parasympathetic action potentials to the stomach (pink arrow), where enteric plexus neurons are activated. 1 Tactile sensation in mouth Hypothalamus 3 Postganglionic neurons stimulate secretion by parietal and chief cells and stimulate gastrin and histamine secretion by endocrine cells. Medulla oblongata Secretions stimulated 4 Gastrin is carried through the circulation back to the stomach (purple arrow), where, along with histamine, it stimulates secretion. 4 Vagus nerves 2 (a) 3 Histamine Gastrin Circulation Stomach Gastric Phase 1 Distention of the stomach stimulates mechanoreceptors (stretch receptors) and activates a parasympathetic reflex. Action potentials generated by the mechanoreceptors are carried by the vagus nerves to the medulla oblongata (green arrow). Vagus nerves Medulla oblongata 2 The medulla oblongata increases action potentials in the vagus nerves that stimulate secretions by parietal and chief cells and stimulate gastrin and histamine secretion by endocrine cells (pink arrow). 1 Secretions stimulated Secretions stimulated 3 Distention of the stomach also activates local reflexes that increase stomach secretions (orange arrow). 2 4 Distention 3 4 Gastrin is carried through the circulation back to the stomach (purple arrow), where, along with histamine, it stimulates secretion. Histamine Gastrin Circulation (b) Intestinal Phase Stomach 1 Chyme in the duodenum with a pH less than 2 or containing fat digestion products (lipids) inhibits gastric secretions by three mechanisms (2–4). Vagus nerves 2 Chemoreceptors in the duodenum are stimulated by H+ (low pH) or lipids. Action potentials generated by the chemoreceptors are carried by the vagus nerves to the medulla oblongata (green arrow), where they inhibit parasympathetic action potentials (pink arrow), thereby decreasing gastric secretions. Medulla oblongata Secretions inhibited Decreased gastric secretions Vagus nerves 4 3 Local reflexes activated by H+ or lipids also inhibit gastric secretion (orange arrows). 2 Local reflexes 1 4 Secretin and cholecystokinin produced by the duodenum (brown arrows) decrease gastric secretions in the stomach. pH <2 or lipids 3 (c) Circulation Secretin and cholecystokinin

Fig. 16.12 1 A mixing wave initiated in the body Copyright © McGraw-Hill Education. Permission required for reproduction or display. 1 A mixing wave initiated in the body of the stomach progresses toward the pyloric sphincter (pink arrows directed inward). Esophagus Mixing wave Chyme Pyloric sphincter 2 The more fluid part of the chyme is pushed toward the pyloric sphincter (blue arrows), whereas the more solid center of the chyme squeezes past the peristaltic constriction back toward the body of the stomach (orange arrow). 1 Duodenum Body of stomach 2 More solid chyme 3 Peristaltic waves (purple arrows) move in the same direction and in the same way as the mixing waves but are stronger. Pyloric region More fluid chyme 4 Again, the more fluid part of the chyme is pushed toward the pyloric region (blue arrows), whereas the more solid center of the chyme squeezes past the peristaltic constriction back toward the body of the stomach (orange arrow). 3 5 Peristaltic contractions force a few milliliters of the most fluid chyme through the pyloric opening into the duodenum (small red arrows). Most of the chyme, including the more solid portion, is forced back toward the body of the stomach for further mixing (yellow arrow). 4 5

Stomach Duodenum Ascending colon Jejunum Mesentery Ileocecal junction Fig. 16.13 Copyright © McGraw-Hill Education. Permission required for reproduction or display. Stomach Duodenum Ascending colon Jejunum Mesentery Ileocecal junction Ileum Cecum Appendix

Fig. 16.14 Copyright © McGraw-Hill Education. Permission required for reproduction or display. Villi Blood capillary network Lacteal Circular folds Epithelium Epithelium Submucosa Intestinal gland Circular muscle Longitudinal muscle Serosa Duodenal gland (a) (b) Top of circular fold Microvilli of epithelial cell surface Epithelial Villus cell Capillary (blood) Lacteal (lymph) (d) (c)

A secretion introduced into the digestive tract or into food within Fig. 16.15 Copyright © McGraw-Hill Education. Permission required for reproduction or display. 1 A secretion introduced into the digestive tract or into food within the tract begins in one location. Secretion or food 1 2 Segments of the digestive tract alternate between contraction and relaxation. Contraction waves 2 3 Material (brown) in the intestine is spread out in both directions from the site of introduction. 3 4 Contraction waves 4 The secretion or food is spread out in the digestive tract and becomes more diffuse (lighter color) through time.

A wave of smooth muscle relaxation moves Fig. 16.9 Copyright © McGraw-Hill Education. Permission required for reproduction or display. Digestive tract Bolus 1 Wave of relaxation 1 A wave of smooth muscle relaxation moves ahead of the bolus, allowing the digestive tract to expand. 2 A wave of contraction of the smooth muscle behind the bolus propels it through the digestive tract. Bolus moves. 2 Wave of contraction

©CNRI/SPL/Science Source Fig. 16.21 Copyright © McGraw-Hill Education. Permission required for reproduction or display. Transverse colon Left colic flexure Right colic flexure Ascending colon Descending colon Ileum Teniae coli Ileocecal valve Cecum Appendix Sigmoid colon Rectum Internal anal sphincter Anal canal (a) External anal sphincter (b) ©CNRI/SPL/Science Source

Fig. 16.16 Copyright © McGraw-Hill Education. Permission required for reproduction or display. Inferior vena cava Right lobe Left lobe Falciform ligament Round ligament Liver Gallbladder (a) Gallbladder Quadrate lobe Hepatic ducts Right lobe Hepatic portal vein Portal triad Hepatic artery Caudate lobe Left lobe Lesser omentum Inferior vena cava (b) To hepatic vein and inferior vena cava Liver lobule Hepatic cords Central vein Bile canaliculi Hepatic phagocytic cells Hepatic duct Hepatic portal vein Portal triad Hepatic artery Hepatocyte Hepatic sinusoid To common bile duct From aorta (c) From digestive tract

Fig. 13.19 Inferior vena cava Hepatic veins Liver Stomach Copyright © McGraw-Hill Education. Permission required for reproduction or display. Inferior vena cava Hepatic veins Liver Stomach Gastric veins Gallbladder Gastroomental veins Cystic vein Spleen Splenic vein with pancreatic branches Hepatic portal vein Tail of pancreas Duodenum Splenic vein Gastroomental veins Head of pancreas Superior mesenteric vein Inferior mesenteric vein Descending colon Ascending colon Small intestine Appendix

Fig. 16.17 1 The hepatic ducts from the liver lobes Copyright © McGraw-Hill Education. Permission required for reproduction or display. 1 The hepatic ducts from the liver lobes combine to form the common hepatic duct. Liver Gallbladder Hepatic ducts Common hepatic duct 1 2 The common hepatic duct combines with the cystic duct from the gallbladder to form the common bile duct. Cystic duct Spleen Hepatic portalvein 2 Common bile duct 3 The common bile duct joins the pancreatic duct. Accessory pancreatic duct 5 4 The combined duct empties into the duodenum at the duodenal papilla. 4 3 Pancreatic duct Duodenal papilla 5 Pancreatic secretions may also enter the duodenum through an accessory pancreatic duct, which also empties into the duodenum. Pancreas Duodenum (cutaway view)

Fig. 16.18 Brain 1 Vagus nerve stimulation (red arrow) Copyright © McGraw-Hill Education. Permission required for reproduction or display. Brain 1 Vagus nerve stimulation (red arrow) causes the gallbladder to contract, thereby releasing bile into the duodenum. 2 Secretin, produced by the duodenum (purple arrows) and carried through the circulation to the liver, stimulates bile secretion by the liver (green arrows inside the liver). 1 Vagus nerves 3 Cholecystokinin, produced by the duodenum (pink arrows) and carried through the circulation to the gallbladder, stimulates the gallbladder to contract and the sphincters to relax, thereby releasing bile into the duodenum (green arrow outside the liver). Bile Bile Liver Bile 4 Bile salts also stimulate bile secretion. Over 90% of bile salts are reabsorbed in the ileum and returned to the liver (green arrows), where they stimulate additional secretion of bile salts. 2 Cholecystokinin Secretin Gallbladder Bile Stomach 3 Cholecystokinin Secretin Pancreas Bile salts Circulation 4 Duodenum

Fig. 16.17 1 The hepatic ducts from the liver lobes Copyright © McGraw-Hill Education. Permission required for reproduction or display. 1 The hepatic ducts from the liver lobes combine to form the common hepatic duct. Liver Gallbladder Hepatic ducts Common hepatic duct 1 2 The common hepatic duct combines with the cystic duct from the gallbladder to form the common bile duct. Cystic duct Spleen Hepatic portalvein 2 Common bile duct 3 The common bile duct joins the pancreatic duct. Accessory pancreatic duct 5 4 The combined duct empties into the duodenum at the duodenal papilla. 4 3 Pancreatic duct Duodenal papilla 5 Pancreatic secretions may also enter the duodenum through an accessory pancreatic duct, which also empties into the duodenum. Pancreas Duodenum (cutaway view)

Fig. 16.18 Brain 1 Vagus nerve stimulation (red arrow) Copyright © McGraw-Hill Education. Permission required for reproduction or display. Brain 1 Vagus nerve stimulation (red arrow) causes the gallbladder to contract, thereby releasing bile into the duodenum. 2 Secretin, produced by the duodenum (purple arrows) and carried through the circulation to the liver, stimulates bile secretion by the liver (green arrows inside the liver). 1 Vagus nerves 3 Cholecystokinin, produced by the duodenum (pink arrows) and carried through the circulation to the gallbladder, stimulates the gallbladder to contract and the sphincters to relax, thereby releasing bile into the duodenum (green arrow outside the liver). Bile Bile Liver Bile 4 Bile salts also stimulate bile secretion. Over 90% of bile salts are reabsorbed in the ileum and returned to the liver (green arrows), where they stimulate additional secretion of bile salts. 2 Cholecystokinin Secretin Gallbladder Bile Stomach 3 Cholecystokinin Secretin Pancreas Bile salts Circulation 4 Duodenum

Fig. 16.19 Common bile duct Jejunum Duodenum Pancreatic duct Copyright © McGraw-Hill Education. Permission required for reproduction or display. Fig. 16.19 Common bile duct Jejunum Duodenum Pancreatic duct Body of pancreas Accessory pancreatic duct Tail of pancreas Duodenal papilla Head of pancreas (a) Pancreatic islet Acini cells (secrete enzymes) Cells producing glucagon Cells producing insulin Vein To pancreatic duct To bloodstream (b)

Fig. 16.20 Brain Stomach Vagus nerves 1 Pancreatic juices 1 Copyright © McGraw-Hill Education. Permission required for reproduction or display. Brain Stomach Vagus nerves 1 Pancreatic juices 1 Parasympathetic stimulation from the vagus nerve (red arrow) causes the pancreas to release a secretion rich in digestive enzymes. 2 Secretin 2 Secretin (purple arrows), released from the duodenum, stimulates the pancreas to release a watery secretion, rich in bicarbonate ions. Cholecystokinin 3 Pancreas Duodenum 3 Cholecystokinin (pink arrows), released from the duodenum, causes the pancreas to release a secretion rich in digestive enzymes. Circulation Cholecystokinin Secretin

Fig. 16.24 Villus Capillary Lacteal Intestinal epithelial cell Copyright © McGraw-Hill Education. Permission required for reproduction or display. Villus Capillary Lacteal Intestinal epithelial cell Monosaccharide (glucose) transport 1 Glucose is absorbed by symport with Na+ into intestinal epithelial cells. 2 Symport is driven by a sodium gradient established by a Na+–K+ pump. Glucose 4 3 1 3 Glucose moves out of the intestinal epithelial cells by facilitated diffusion. Na + Na + Glucose enters the capillaries of the intestinal villi and is carried through the hepatic portal vein to the liver. A TP 4 ADP 2 Na + K + To liver

Fig. 16.27 Villus Capillary Lacteal Amino acid transport Intestinal Copyright © McGraw-Hill Education. Permission required for reproduction or display. Villus Capillary Lacteal Amino acid transport Intestinal epithelial cell 1 Acidic and most neutral amino acids are absorbed by symport into intestinal epithelial cells. 2 Symport is driven by a sodium gradient established by a Na+–K+ pump. Amino acid 3 3 4 Amino acids move out of intestinal epithelial cells. 1 4 Amino acids enter the capillaries of the intestinal villi and are carried through the hepatic portal vein to the liver. Na + Na + A TP ADP Na + K + 2 To liver

Fig. 13.19 Inferior vena cava Hepatic veins Liver Stomach Copyright © McGraw-Hill Education. Permission required for reproduction or display. Inferior vena cava Hepatic veins Liver Stomach Gastric veins Gallbladder Gastroomental veins Cystic vein Spleen Splenic vein with pancreatic branches Hepatic portal vein Tail of pancreas Duodenum Splenic vein Gastroomental veins Head of pancreas Superior mesenteric vein Inferior mesenteric vein Descending colon Ascending colon Small intestine Appendix

Fig. 16.25 Lipid transport Villus 1 Copyright © McGraw-Hill Education. Permission required for reproduction or display. Lipid transport Villus 1 Bile salts surround fatty acids and monoglycerides to form micelles. Capillary Lacteal 2 Micelles attach to the plasma membranes of intestinal epithelial cells, and the fatty acids and monoglycerides pass by simple diffusion into the intestinal epithelial cells. Intestinal epithelial cell Micelles contact epithelial cell membrane. 3 Within the intestinal epithelial cell, the fatty acids and monoglycerides are converted to triglycerides; proteins coat the triglycerides to form chylomicrons, which move out of the intestinal epithelial cells by exocytosis. 1 Triglycerides Protein coat 4 3 Bile salt Fatty acids and monoglycerides 2 Simple diffusion Exocytosis 4 The chylomicrons enter the lacteals of the intestinal villi and are carried through the lymphatic system to the general circulation. Micelle Chylomicron Lymphatic system

Tonsils Cervical lymph node Right lymphatic duct Thoracic duct Thymus Fig. 14.1-1 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Tonsils Cervical lymph node Right lymphatic duct Thoracic duct Thymus Axillary lymph node Subclavian veins Thoracic duct Mammary plexus Spleen Lacteals in intestinal wall Lymphatic vessel (transports lymph) Inguinal lymph node Bone marrow (a)

Fig. 16.28 Ingestion (2 L) Salivary gland secretions (1 L) Gastric Copyright © McGraw-Hill Education. Permission required for reproduction or display. Ingestion (2 L) Salivary gland secretions (1 L) Gastric secretions (2 L) Pancreatic secretions (1.2 L) Bile (0.7 L) 92% absorbed in the small intestine Small intestine secretions (2 L) 6%–7% absorbed in the large intestine Ingestion or secretion Absorption 1% in feces (Water infeces = Ingested + Secreted – Absorbed)

©CNRI/SPL/Science Source Fig. 16.21 Copyright © McGraw-Hill Education. Permission required for reproduction or display. Transverse colon Left colic flexure Right colic flexure Ascending colon Descending colon Ileum Teniae coli Ileocecal valve Cecum Appendix Sigmoid colon Rectum Internal anal sphincter Anal canal (a) External anal sphincter (b) ©CNRI/SPL/Science Source

Fig. 16.3 Liver Visceral peritoneum Lesser omentum Stomach Copyright © McGraw-Hill Education. Permission required for reproduction or display. Liver Visceral peritoneum Lesser omentum Stomach Peritoneal cavity containing peritoneal fluid Pancreas (retroperitoneal) Kidney (retroperitoneal) Parietal peritoneum Duodenum (retroperitoneal) Greater omentum Transverse colon Omental bursa Mesentery proper Small intestine Urinary bladder (retroperitoneal) Rectum (retroperitoneal) Medial view