Mouth (Oral Cavity) Tongue Parotid Gland Sublingual Gland

Home , Appendix (anatomy), Ascending colon, Duodenum, Haustrum (anatomy), Ileum, Jejunum

Mouth (oral cavity) Parotid gland Tongue Sublingual gland Salivary Submandibular glands gland

Stomach Pancreas (Spleen) Liver Gallbladder Transverse colon

Duodenum Descending colon Small Jejunum Ascending colon intestine Ileum Large Cecum intestine Sigmoid colon Rectum Appendix Anus Anal canal © 2018 Pearson Education, Inc. 1 Nasopharynx Hard palate Soft palate Oral cavity Uvula

Lips (labia) Palatine tonsil

Vestibule Lingual tonsil

Oropharynx Lingual frenulum

Epiglottis Tongue Laryngopharynx Hyoid bone

Soft palate

Uvula

Palatine tonsil

Oropharynx Tongue (b)

Lips (labia) Palatine tonsil

Vestibule Lingual tonsil

Oropharynx Lingual frenulum

Epiglottis Tongue Laryngopharynx Hyoid bone

Submucosal glands

Mucosa • Surface epithelium • Lamina propria • Muscle layer

Submucosa Muscularis externa • Longitudinal muscle layer • Circular muscle layer Serosa (visceral peritoneum) Nerve Gland in Lumen Artery mucosa Mesentery Vein Duct of gland Lymphoid tissue outside alimentary canal

© 2018 Pearson Education, Inc. 5 Diaphragm Falciform ligament Lesser Liver omentum Spleen Pancreas Gallbladder Stomach Duodenum Visceral peritoneum Transverse Greater omentum colon Mesenteries Parietal peritoneum

Small intestine Peritoneal cavity Uterus

Large intestine Cecum Rectum Anus Urinary bladder

(a) (b)

Esophagus

Muscularis Serosa externa • Longitudinal layer • Circular layer • Oblique layer Body

Lesser Rugae curvature of Pylorus mucosa

Greater curvature

Body

Rugae of mucosa

Surface epithelium

Pyloric

sphincter pit Gastric Mucous neck cells

Parietal cells

Gastric

Gastric gland Gastric glands

Chief cells

Parietal cells

Chief cells

Enteroendocrine (d) cell

Cystic duct Common hepatic duct Bile duct and sphincter Accessory pancreatic duct

Pancreas Gallbladder Jejunum Duodenal papilla Main pancreatic duct and sphincter Hepatopancreatic ampulla and sphincter Duodenum © 2018 Pearson Education, Inc. 11 Blood vessels serving the small intestine

Lumen Muscle layers Circular folds (plicae circulares) Villi

(a) Small intestine

Lacteal

Villus Blood capillaries

Lymphoid tissue Intestinal crypt Muscularis Venule mucosae Lymphatic vessel

Transverse colon

Haustrum Descending colon

Ascending colon

IIeum (cut) Cut edge of mesentery IIeocecal valve Teniae coli

Sigmoid colon Cecum

Appendix Rectum

Anal canal External anal sphincter

Root canal Root Periodontal membrane (ligament)

Starch and disaccharides Digestion of Salivary amylase Mouth carbohydrates Pancreatic amylase Small intestine Oligosaccharides* and disaccharides

Brush border enzymes Small intestine Lactose Maltose Sucrose in small intestine (dextrinase, glucoamylase, lactase, maltase, Galactose Glucose Fructose and sucrase)

The monosaccharides glucose, galactose, and fructose Absorption of enter the capillary blood in the villi and are transported to carbohydrates the liver via the hepatic portal vein.

*Oligosaccharides consist of a few linked monosaccharides.

Protein Digestion of proteins Pepsin (stomach glands) Stomach in the presence of HCl Large polypeptides

Pancreatic enzymes Small intestine (trypsin, chymotrypsin, Small polypeptides carboxypeptidase)

Brush border enzymes Small intestine (aminopeptidase, Amino acids carboxypeptidase, (some dipeptides and dipeptidase) and tripeptides)

Absorption Amino acids enter the capillary blood in the villi and are of proteins transported to the liver via the hepatic portal vein.

Unemulsified fats Digestion of fats Emulsified by the Small intestine detergent action of bile salts from the liver

Pancreatic lipase Small intestine

Monoglycerides Glycerol and and fatty acids fatty acids

Fatty acids and monoglycerides enter the lacteals of the villi Absorption and are transported to the systemic circulation via the lymph of fats in the thoracic duct. (Glycerol and short-chain fatty acids are absorbed into the capillary blood in the villi and transported to the liver via the hepatic portal vein.)

© 2018 Pearson Education, Inc. 19 Ingestion Food Mechanical Pharynx breakdown • Chewing (mouth) Esophagus • Churning (stomach) Propulsion • Segmentation • Swallowing (small intestine) (oropharynx) • Peristalsis Digestion (esophagus, stomach, small intestine, large intestine) Stomach

Absorption Lymph vessel

Small intestine Blood Large vessel intestine Mainly H2O Feces

Anus Defecation

Tongue

Pharynx Epiglottis up Upper esophageal Glottis (lumen) sphincter of larynx

Trachea Esophagus

1 Upper esophageal sphincter contracted

Larynx up Esophagus

2 Upper esophageal sphincter relaxed

3 Upper esophageal sphincter contracted

Cardioesophageal sphincter open

4 Cardioesophageal sphincter relaxed

1 Propulsion: Peristaltic 2 Grinding: The most 3 Retropulsion: The waves move from the fundus vigorous peristalsis and peristaltic wave closes the toward the pylorus. mixing action occur close pyloric valve, forcing most of to the pylorus. The pyloric the contents of the pylorus end of the stomach acts as backward into the stomach. a pump that delivers small amounts of chyme into the duodenum.

© 2018 Pearson Education, Inc. 25 4 Secretin causes the liver to secrete more bile; CCK stimulates the gallbladder 1 Chyme entering to release stored duodenum causes bile and the duodenal entero- hepatopancreatic endocrine cells to sphincter to relax release cholecystokinin (allows bile from (CCK) and secretin. both sources to enter the duodenum). 2 CCK (red dots) and secretin (blue dots) 5 Stimulation enter the bloodstream. by vagal nerve fibers causes 3 Upon reaching the release of pancreas, CCK induces pancreatic juice secretion of enzyme- and weak rich pancreatic juice; contractions of secretin causes the gallbladder. secretion of bicarbonate- rich pancreatic juice.

© 2018 Pearson Education, Inc. 28 (a) Carbohydrates: polysaccharides, disaccharides; composed of simple sugars (monosaccharides) ATP Glycogen and fat Polysaccharides Cellular uses broken down for ATP formation GI digestion to simple sugars To Excess stored as capillary glycogen or fat Broken down to glucose Monosaccharides and released to blood

© 2018 Pearson Education, Inc. 29 (b) Fats: composed of 1 glycerol molecule and 3 fatty acids; triglycerides Cellular ATP Fats are the Metabolized uses Lipid (fat) primary fuels Fatty by liver to in many cells acids GI digestion acetic acid, etc. to fatty acids and glycerol Insulation and fat Fats build myelin cushions to protect sheaths and cell body organs membranes Glycerol

© 2018 Pearson Education, Inc. 30 (c) Proteins: polymers of amino acids ATP formation if inadequate ATP glucose and fats or if essential Protein Normally amino acids are lacking infrequent Functional proteins GI digestion to (enzymes, antibodies, amino acids Cellular hemoglobin, etc.) uses Structural proteins Amino (connective tissue fibers, acids muscle proteins, etc.)

© 2018 Pearson Education, Inc. 31 (d) ATP formation (fueling the metabolic furnace): all categories of food can be oxidized to provide energy molecules (ATP) Carbon dioxide Cellular Monosaccharides metabolic “furnace”: Water Citric acid cycle Fatty acids and electron transport Amino acids chain (amine first removed ATP and combined with CO2 by the liver to form urea)

IMBALANCE Stimulus: Rising blood glucose level HOMEOSTATIC BLOOD SUGAR

Stimulus: IMBALANCE Falling blood glucose level Glycogenolysis: Stored glycogen converted to glucose