1. Human Anatomy, 3rd edition
The Digestive System
Chapter 25
Human Anatomy, 3rd edition
Prentice Hall, © 2001

2. Human Anatomy, 3rd edition
Introduction
Structure of the digestive system
A tube that extends from mouth to anus
Accessory organs are attached
Functions include
Ingestion
Movement
Digestion
Absorption
Defecation
Human Anatomy, 3rd edition
Prentice Hall, © 2001

3. Overview of Digestive System
FG25_01.JPG
Title: Components of the Digestive System
Notes: This figure introduces the accessory organs and major regions of the digestive tract, together with their primary functions.
Keywords: digestive system, components, oral cavity, teeth, tongue, liver, gallbladder, large intestine, salivary glands, pharynx, esophagus, stomach, pancreas, small intestine
Human Anatomy, 3rd edition
Prentice Hall, © 2001

4. Histological Organization
The wall of the digestive tract has the same basic arrangement of tissues from the esophagus to the anal canal
Four layers (from innermost to outermost)
Mucosa
Submucosa
Muscularis
Serosa
Human Anatomy, 3rd edition
Prentice Hall, © 2001

5. Layers of the Digestive Tract
FG25_02A1.JPG
Title: Histological Structure of the Digestive Tract
Notes: (a) Three-dimensional view of the histological organization of the digestive tube. (b)Photomicrograph of ileum; histological organization.
Keywords: digestive tract, histology, mesentery, plica, mucosa, submucosa, muscularis externa, visceral peritoneum, serosa, villi, mucosal glands, lymphatic vessel, muscularis mucosae, myenteric plexus, longitudinal muscle layer, circular muscle
Human Anatomy, 3rd edition
Prentice Hall, © 2001

6. Layers of the Digestive Tract
FG25_02A2.JPG
Title: Histological Structure of the Digestive Tract
Notes: (a) Three-dimensional view of the histological organization of the digestive tube. (b)Photomicrograph of ileum; histological organization.
Keywords: digestive tract, histology, mesentery, plica, mucosa, submucosa, muscularis externa, visceral peritoneum, serosa, villi, mucosal glands, lymphatic vessel, muscularis mucosae, myenteric plexus, longitudinal muscle layer, circular muscle
Human Anatomy, 3rd edition
Prentice Hall, © 2001

7. Movement & Mixing of Digestive Materials
Peristalsis
Coordinated motion of the two muscular layers
Circular muscles contract, then longitudinal muscles
Segmentation
Mixing of food
Circular muscles in two areas contract
Longitudinal muscles alternately contract & relax
Human Anatomy, 3rd edition
Prentice Hall, © 2001

8. Peristalsis & Segmentation
FG25_03.JPG
Title: Peristalsis and Segmentation
Notes: (a)Peristalsis propels materials along the length of the digestive tract by coordinated contractions of the circular and longitudinal layers. (b)Segmentation movements involve circular layers; mix and churn, but no directional movement.
Keywords: peristalsis, contractions, circular, longitudinal, bolus, segmentation, churn
Human Anatomy, 3rd edition
Prentice Hall, © 2001

9. Human Anatomy, 3rd edition
The Oral Cavity
Functions
Take in food
Prepare food for digestion
Structure
Lined with stratified squamous epithelium
Lips surround the opening
Roof is formed from the hard & soft palate
Tongue dominates the floor
Human Anatomy, 3rd edition
Prentice Hall, © 2001

10. Human Anatomy, 3rd edition
Oral Cavity
FG25_05A.JPG
Title: The Oral Cavity
Notes: (a) The oral cavity as seen in sagittal section. (b) An anterior view of the oral cavity, as seen through the open mouth.
Keywords: oral cavity, sagittal, epiglottis, tonsil, nasopharynx, oropharynx, soft palate, tongue, hard palate, lingual frenulum, submandibular ducts, palatoglossal arch, uvula
Human Anatomy, 3rd edition
Prentice Hall, © 2001

11. Human Anatomy, 3rd edition
Oral Cavity
FG25_05B.JPG
Title: The Oral Cavity
Notes: (a) The oral cavity as seen in sagittal section. (b) An anterior view of the oral cavity, as seen through the open mouth.
Keywords: oral cavity, sagittal, epiglottis, tonsil, nasopharynx, oropharynx, soft palate, tongue, hard palate, lingual frenulum, submandibular ducts, palatoglossal arch, uvula
Human Anatomy, 3rd edition
Prentice Hall, © 2001

12. Human Anatomy, 3rd edition
The Tongue
Functions
Maneuvers food
Structure
Skeletal muscle covered with mucosa
The lingual frenulum connects the tongue to the floor of the mouth
Surface
Papillae
Human Anatomy, 3rd edition
Prentice Hall, © 2001

13. Human Anatomy, 3rd edition
The Salivary Glands
Found outside the mouth
Ducts carry saliva to the mouth
Saliva
Functions
Keeps mucous membranes moist
Lubricates food
Dissolves food
Begins carbohydrate digestion
3 pairs
Parotid glands
Submandibular glands
Sublingual glands
Human Anatomy, 3rd edition
Prentice Hall, © 2001

14. Human Anatomy, 3rd edition
Salivary Glands
FG25_06A.JPG
Title: The Salivary Glands
Notes: (a) Lateral view, showing the relative positions of the salivary glands and ducts on the left side of the head. (b)Photomicrograph showing histological detail of parotid, submandibular, and sublingual salivary glands.
Keywords: salivary glands, ducts, lingual frenulum, sublingual duct, sublingual salivary, submandibular, parotid, serous cells, mucous cells, enzymes, mucins
Human Anatomy, 3rd edition
Prentice Hall, © 2001

15. Human Anatomy, 3rd edition
Teeth
2 sets
Deciduous (20)
Permanent (32)
Held in sockets
Gingiva surrounds the base of the teeth
Structure
Crown
Root
Neck
Composition
Dentin – primary substance in tooth
Enamel – covers crown
Cementum – covers root
Tooth decay
Wisdom teeth – 3rd molars
Human Anatomy, 3rd edition
Prentice Hall, © 2001

16. Human Anatomy, 3rd edition
A Tooth
FG25_07A.JPG
Title: Teeth
Notes: (a) Diagrammatic section through a typical adult tooth. (b)Adult teeth. (c)Dental reference terms and normal teeth orientation. (d)Primary teeth. (e)Skull of a child, exposing unerupted permanent teeth.
Keywords: tooth, crown, neck, root, pulp cavity, enamel, dentin, gingival sulcus, cementum, periodontal ligament, root canal, alveolar bone, apical foramen, alveolar vessels, nerve, incisor, cuspid, bicuspid, molar, canines, distal surface, medial surface, dental reference terms
Human Anatomy, 3rd edition
Prentice Hall, © 2001

17. The Pharynx and Esophagus
Food enters the esophagus from the pharynx
The esophagus is a muscular tube behind the trachea
Food is moved by peristalsis from the pharynx to the stomach
Cardiac sphincter separates esophagus from stomach
Human Anatomy, 3rd edition
Prentice Hall, © 2001

18. Human Anatomy, 3rd edition
The Esophagus
FG25_09A.JPG
Title: The Esophagus
Notes: (a)Low-power view of a section through the esophagus. (b)The esophageal mucosa.
Keywords: esophagus, muscularis mucosae, mucosa, submucosa, adventitia, muscularis externa, stratified squamous epithelium, lamina propria
Human Anatomy, 3rd edition
Prentice Hall, © 2001

19. Human Anatomy, 3rd edition
The Stomach
Has the same 4 basic layers
When the stomach is empty, the mucosa lies in large folds
Rugae
Pyloric sphincter separates stomach from small intestine
Human Anatomy, 3rd edition
Prentice Hall, © 2001

20. External Anatomy of the Stomach
FG25_10A.JPG
Title: The Stomach and Omenta
Notes: (a) Surface anatomy of the stomach, showing blood vessels and relation to liver and intestines. (b)Radiograph of stomach and duodenum after swallowing barium solution to increase contrast. (c)Radiograph of pyloric region, pyloric valve, and duodenum.
Keywords: stomach, surface, lesser curvature, gastroepiploic artery, greater curvature, omentum, hepatoduodenal ligament, hepatogastric ligament, duodenum, pylorus, rugae, pyloric sphincter, fundus, body
Human Anatomy, 3rd edition
Prentice Hall, © 2001

21. Human Anatomy, 3rd edition
Anatomy of the Stomach
FG25_11A.JPG
Title: Gross Anatomy of the Stomach
Notes: (a) External and internal anatomy of the stomach. (b)Anterior view of abdominal cavity.
Keywords: stomach, gross anatomy, esophagus, fundus, cardia, longitudinal, circular, oblique, mucosa, gastroepiploic vessels, rugae, pylorus, pyloric sphincter, duodenum, lesser curvature, greater curvature
Human Anatomy, 3rd edition
Prentice Hall, © 2001

22. Histology of the Stomach
Mucosa is simple columnar epithelium with goblet cells
Mucosa is folded to form gastric pits
Gastric glands secrete gastric juice
Several kinds of cells in each gland produce substances that form the gastric juice
Mucus cells
Chief cells
Parietal cells
Enteroendocrine cells
Human Anatomy, 3rd edition
Prentice Hall, © 2001

23. Human Anatomy, 3rd edition
The Stomach Wall
FG25_13C.JPG
Title: Abdominal Regions and Planes
Notes: Diagrammatic view of the abdominal regions and planes.
Keywords: abdominal regions, planes, epigastric, hypochondriac, umbilical, lumbar, inguinal, hypogastric, liver, stomach, pancreas, gallbladder, colon, appendix, small intestine, spleen, rectum
Human Anatomy, 3rd edition
Prentice Hall, © 2001

24. Human Anatomy, 3rd edition
Gastric Gland
FG25_13D.JPG
Title: Abdominal Regions and Planes
Notes: Diagrammatic view of the abdominal regions and planes.
Keywords: abdominal regions, planes, epigastric, hypochondriac, umbilical, lumbar, inguinal, hypogastric, liver, stomach, pancreas, gallbladder, colon, appendix, small intestine, spleen, rectum
Human Anatomy, 3rd edition
Prentice Hall, © 2001

25. Functions of the Stomach
Mechanical digestion
Food reaches pylorus
Chemical digestion
Digestion of proteins
Absorption
No food
Water, electrolytes
Some drugs
Alcohol
Human Anatomy, 3rd edition
Prentice Hall, © 2001

26. Human Anatomy, 3rd edition
The Small Intestine
About 18 feet long
3 regions
The duodenum (= “12 fingers’ length”)
About 8 inches long
Common bile duct & pancreatic duct empty here
The jejunum (= “empty”)
About 8 feet long
Most digestion occurs here
The ileum
About 9.5 feet long
Most absorption occurs here
Ends in the ileocecal valve
Human Anatomy, 3rd edition
Prentice Hall, © 2001

27. Regions of the Small Intestine
FG25_14.JPG
Title: Regions of the Small Intestine
Notes: (a)The color coding indicates the relative sizes and positions of the duodenum, jejunum, and ileum. (b)Anterior view of abdominopelvic viscera
Keywords: small intestine, regions, duodenum, jejunum, large intestine, ileum
Human Anatomy, 3rd edition
Prentice Hall, © 2001

28. Histology of the Small Intestine
The lining is folded into circular pleats called plicae circulares
The mucosal surface is folded into villi
The epithelial cell membranes are highly folded into microvilli
Intestinal glands are found in the crypts (“hidden place” – like gastric pits) at the base of villi
Secrete intestinal juice
Human Anatomy, 3rd edition
Prentice Hall, © 2001

29. Histology of the Small Intestine
FG25_15A.JPG
Title: The Intestinal Wall
Notes: (a) Characteristic features of the intestinal lining.(b) The organization of villi and the intestinal crypts.(c) Diagrammatic view of a single villus. (d)Panoramic view of small intestine wall. (e)Villi photomicrographs from jejunum.
Keywords: villi, intestinal crypts, mucosa, muscularis mucosae, submucosa, muscularis externa, serosa, lacteal, lymphoid nodule, intestinal glands, submucosal plexus, lymphatic vessel, myenteric plexus, plica, goblet cell, lacteal, brush border
Human Anatomy, 3rd edition
Prentice Hall, © 2001

30. Human Anatomy, 3rd edition
A Villus
FG25_15C.JPG
Title: The Intestinal Wall
Notes: (a) Characteristic features of the intestinal lining.(b) The organization of villi and the intestinal crypts.(c) Diagrammatic view of a single villus. (d)Panoramic view of small intestine wall. (e)Villi photomicrographs from jejunum.
Keywords: villi, intestinal crypts, mucosa, muscularis mucosae, submucosa, muscularis externa, serosa, lacteal, lymphoid nodule, intestinal glands, submucosal plexus, lymphatic vessel, myenteric plexus, plica, goblet cell, lacteal, brush border
Human Anatomy, 3rd edition
Prentice Hall, © 2001

31. Functions of the Small Intestine
Chyme is further broken down
Proteins
Carbohydrates
Fats
Most absorption is in the small intestine
Human Anatomy, 3rd edition
Prentice Hall, © 2001

32. Human Anatomy, 3rd edition
The Large Intestine
– AKA colon
About 4.5 feet long
Mesocolon supports
Begins with the cecum
Appendix is attached
Ascending colon
Transverse colon
Descending colon
Sigmoid colon
Colon connects to the rectum
Rectum connects to the anal canal which empties to the exterior through the anus
Human Anatomy, 3rd edition
Prentice Hall, © 2001

33. Human Anatomy, 3rd edition
The Large Intestine
FG25_17A.JPG
Title: The Large Intestine
Notes: (a) Gross anatomy and regions of the large intestine.(b) The cecum and veriform appendix.(c) Detailed anatomy of the rectum and anus.
Keywords: large intestine, cecum, ileocecal valve, epiploic appendages, ascending, colon, descending, colic flexure, transverse, omentum, haustra, taenia coli, sigmoid, ileocecal valve, rectum, anus, anorectal canal
Human Anatomy, 3rd edition
Prentice Hall, © 2001

34. Histology & Functions of the Large Intestine
Mucosa - simple columnar epithelium (thin)
Completion of absorption
Formation of feces
Lots of mucus glands
Expulsion of feces from the body
Human Anatomy, 3rd edition
Prentice Hall, © 2001

35. Digestion in the Large Intestine
Mechanical
Regulated by the ileocecal valve
Mixing and peristalsis
Mass peristalsis
Chemical
Mucus secreted
No enzymes
Bacteria – prepare chyme for elimination
Human Anatomy, 3rd edition
Prentice Hall, © 2001

36. Feces Formation & Defecation
Chyme is now solid or semi-solid - feces
Large intestine absorbs any more water and electrolytes from feces
Defecation
Mass peristalsis pushes fecal material into rectum
Rectum stretches
Defecation reflex
Human Anatomy, 3rd edition
Prentice Hall, © 2001

37. Histology of the Large Intestine
FG25_19.JPG
Title: The Wall of the Large Intestine
Notes: (a) Three-dimensional view of the colon wall. (b)Photomicrograph of colon, showing detail of mucosal and submucosal layers.
Keywords: colon wall, taenia coli, epiploic appendages, haustrum, columnar epithelium, intestinal gland, muscularis mucosae, submucosa, muscularis externa, circular, longitudinal
Human Anatomy, 3rd edition
Prentice Hall, © 2001

38. Human Anatomy, 3rd edition
Accessory Organs
Liver
Pancreas
Gall bladder
Human Anatomy, 3rd edition
Prentice Hall, © 2001

39. Human Anatomy, 3rd edition
The Liver
Performs many life-sustaining functions, digestive and other.
Location – under the diaphragm on the left
Connected to the diaphragm by the falciform ligament
Divided into lobes
Right lobe
Left lobe
Caudate lobe
Quadrate lobe
Human Anatomy, 3rd edition
Prentice Hall, © 2001

40. Human Anatomy, 3rd edition
The Liver
FG25_20C.JPG
Title: Anatomy of the Liver
Notes: (a) Horizontal section through the upper abdomen. (b)Horizontal section through upper abdomen; cadaver. (c)Anatomical landmarks; anterior liver surface. (d)Posterior surface of liver.
Keywords: liver, horizontal, stomach, falciform ligament, caudate, lobe, inferior vena cava, aorta, spleen, sternum, kidney, right lobe, gallbladder, round ligament, left lobe, hepatic vein, hepatic portal vein, hepatic artery, quadrate lobe, common bile duct, porta hepatis
Human Anatomy, 3rd edition
Prentice Hall, © 2001

41. Human Anatomy, 3rd edition
The Liver
FG25_20D.JPG
Title: Anatomy of the Liver
Notes: (a) Horizontal section through the upper abdomen. (b)Horizontal section through upper abdomen; cadaver. (c)Anatomical landmarks; anterior liver surface. (d)Posterior surface of liver.
Keywords: liver, horizontal, stomach, falciform ligament, caudate, lobe, inferior vena cava, aorta, spleen, sternum, kidney, right lobe, gallbladder, round ligament, left lobe, hepatic vein, hepatic portal vein, hepatic artery, quadrate lobe, common bile duct, porta hepatis
Human Anatomy, 3rd edition
Prentice Hall, © 2001

42. Human Anatomy, 3rd edition
Histology of the Liver
- Outside is a capsule
- Composed of tiny lobules
Each lobule is surrounded by liver cells and sinusoids
Bile ducts run between liver cells
Human Anatomy, 3rd edition
Prentice Hall, © 2001

43. Histology and Blood Supply of the Liver
FG25_21A.JPG
Title: Liver Histology
Notes: (a) Diagrammatic view of lobular organization. (b)Light micrograph; liver lobule. (c)Light micrograph; detail of portal area.
Keywords: liver, lobular organization, connective tissue, hepatic artery, bile duct, hepatocytes, hepatic portal vein, interlobular septum, portal area, bile ductules, central vein, vile canaliculi, sinusoid
Human Anatomy, 3rd edition
Prentice Hall, © 2001

44. Human Anatomy, 3rd edition
Functions of the Liver
Produces bile – the primary digestive function
Composition
Water
Bile salts
Cholesterol
Pigments
Bilirubin
Digestive function
Emulsification of fats
Human Anatomy, 3rd edition
Prentice Hall, © 2001

45. Other Functions of the Liver
Absorbs and stores iron, vitamins A, D, E, B7, K
Detoxifies toxins and hormones
Metabolizes proteins, carbohydrates, and lipids
Removes bacteria from the blood
Kupffer cells
Produces plasma proteins
Removes worn-out and damaged red blood cells
Human Anatomy, 3rd edition
Prentice Hall, © 2001

46. Human Anatomy, 3rd edition
The Gallbladder
Location – underside of the left lobe of the liver
Function – to concentrate and store bile
Gallstones
Cholesterol in bile crystalizes, crystals fuse.
Human Anatomy, 3rd edition
Prentice Hall, © 2001

47. Human Anatomy, 3rd edition
The Gallbladder
FG25_22A.JPG
Title: The Gallbladder and Associated Bile Ducts
Notes: (a) A view of the inferior surface of the liver. (b)Common bile duct, hepatic duct, and cystic duct. (c) Radiograph of gallbladder, biliary ducts, and pancreatic ducts, anterior/posterior view.
Keywords: gallbladder, liver, duodenum, fundus, body, neck, common bile duct, cystic duct, common hepatic duct, portal vein, hepatic artery, gastric artery, duodenal ampulla, pancreaticohepatic sphincter, pancreatic duct
Human Anatomy, 3rd edition
Prentice Hall, © 2001

48. Human Anatomy, 3rd edition
The Pancreas
- Location – in the curvature of the duodenum
Connected to the duodenum by the pancreatic duct
Produces pancreatic juic
Functions
Exocrine - digestion of all the nutrient groups
Endocrine – production of insulin & glucagon
Control level of blood glucose
Human Anatomy, 3rd edition
Prentice Hall, © 2001

49. Human Anatomy, 3rd edition
The Pancreas
FG25_23A.JPG
Title: The Pancreas
Notes: (a) Gross anatomy of the pancreas. (b)Diagrammatic view of pancreatic cellular organization; exocrine and endocrine regions. (c)Photomicrograph of pancreas; endocrine and exocrine regions.
Keywords: pancreas, head, tail, lobule, transverse artery, body, pancreatic duct, accessory pancreatic duct, artery, endocrine, exocrine, islet, acinar
Human Anatomy, 3rd edition
Prentice Hall, © 2001