23 - Los Angeles Harbor College

23 - Los Angeles Harbor College

1 CHAPTER 23 (8th edition) THE DIGESTIVE SYSTEM part 1 Copyright 2011 Pearson Education, Inc. 2. Digestive System Two groups of organs 1. Alimentary canal (gastrointestinal or GI tract) Digests and absorbs food Mouth, pharynx, esophagus, stomach, small intestine, and large intestine

Copyright 2011 Pearson Education, Inc. 3. Digestive System 2. Accessory digestive organs Teeth, tongue, gallbladder Digestive glands Salivary glands Liver

Gall bladder pancreas Copyright 2011 Pearson Education, Inc. 4 Fig. 23.1 Pg 852 Mouth (oral cavity) Tongue Esophagus Liver Gallbladder

Duodenum Jejunum Small intestine Ileum Anus Copyright 2011 Pearson Education, Inc. Parotid gland Sublingual gland Salivary Submandibular glands gland Pharynx Stomach Pancreas (Spleen) Transverse colon Descending colon Ascending colon

Large Cecum intestine Sigmoid colon Rectum Vermiform appendix Anal canal Figure 22.1 5. Digestive Processes Six essential activities 1. Ingestion 2. Propulsion 3. Mechanical digestion (physical change) 4. Chemical digestion (chemical reactions , decomposition, surface area, new stuff) 5. Absorption 6. Defecation

Copyright 2011 Pearson Education, Inc. 6 Fig. 23. Pg. 853 Ingestion Mechanical digestion Chewing (mouth) Churning (stomach) Segmentation (small intestine) Chemical digestion Food Pharynx

Esophagus Propulsion Swallowing (oropharynx) Peristalsis Stomach (esophagus, stomach, small intestine, large intestine) Absorption Lymph vessel Small intestine Large intestine Defecation Copyright 2011 Pearson Education, Inc.

Blood vessel Mainly H2O Feces Anus Figure 22.2 7 Fig. 23.5a; page 855 From mouth (a) Peristalsis: Adjacent segments of alimentary tract organs alternately contract and relax, which moves food along the tract distally. Copyright 2011 Pearson Education, Inc.

(b) Segmentation: Nonadjacent segments of alimentary tract organs alternately contract and relax, moving the food forward then backward. Food mixing and slow food propulsion occurs. Figure 22.3 8. GI tract regulatory mechanisms SKIP 2. Intrinsic and extrinsic controls Enteric nerve plexuses (gut brain) initiate short reflexes in response to stimuli in the GI tract Long reflexes in response to stimuli inside or outside the GI tract involve CNS centers and

autonomic nerves Hormones from cells in the stomach and small intestine stimulate target cells in the same or different organs Copyright 2011 Pearson Education, Inc. 9. Peritoneum and Peritoneal Cavity Peritoneum: serous membrane of the abdominal cavity Visceral peritoneum on external surface of most digestive organs Parietal peritoneum lines the body wall Peritoneal cavity Between the two peritoneums Fluid lubricates mobile organs

Copyright 2011 Pearson Education, Inc. Abdominopelvic cavity Vertebra Dorsal mesentery Parietal peritoneum Ventral mesentery Visceral peritoneum Peritoneal cavity

Alimentary canal organ Liver (a) Schematic cross sections of abdominal cavity illustrate the peritoneums and mesenteries. Copyright 2011 Pearson Education, Inc. Figure 22.5a 11. Peritoneum and Peritoneal Cavity Mesentery is a double layer of peritoneum Routes for blood vessels, lymphatics, and nerves Holds organs in place and stores fat Retroperitoneal organs lie posterior to the peritoneum Intraperitoneal (peritoneal) organs are

surrounded by the peritoneum Copyright 2011 Pearson Education, Inc. 12 Fig. 23.5b; page 855 Abdominopelvic cavity Mesentery resorbed and lost Alimentary Alimentary canal organ in canal organ a retroperitoneal position (b) Some organs lose their mesentery and become retroperitoneal during development. Copyright 2011 Pearson Education, Inc.

Figure 22.5b 13. Blood Supply: Splanchnic Circulation Skip 13-24 Arteries- that branch off the aorta and go to the digestive system and the hepatic portal system Hepatic, splenic, and left gastric Inferior and superior mesenteric Hepatic portal circulation Drains nutrient-rich blood from digestive organs Delivers it to the liver for processing Copyright 2011 Pearson Education, Inc. 14. Histology of the Alimentary Canal Four basic layers (tunics) 1. Mucosa

2. Submucosa 3. Muscularis externa 4. Serosa Copyright 2011 Pearson Education, Inc. 15 Fig. 23.6; page 857 Nerve Artery Vein Mesentery Copyright 2011 Pearson Education, Inc. Intrinsic nerve plexuses Myenteric nerve plexus Submucosal nerve plexus Glands in submucosa Mucosa

Epithelium Lamina propria Muscularis mucosae Submucosa Muscularis externa Longitudinal muscle Circular muscle Serosa Epithelium Connective tissue Lumen Gland in mucosa Lymphatic Mucosa-associated Duct of gland outside vessel

lymphoid tissue alimentary canal Figure 22.6 16. 1. Mucosa Lines the lumen Functions Secretes mucus, digestive enzymes and hormones Absorbs end products of digestion Protects against infectious disease Three sublayers: A. epithelium, B. lamina propria, and C. muscularis mucosae Copyright 2011 Pearson Education, Inc.

17. Mucosa A. Epithelium Simple columnar epithelium and mucussecreting cells Mucus Protects digestive organs from enzymes Eases food passage May secrete enzymes and hormones (e.g., in stomach and small intestine) Copyright 2011 Pearson Education, Inc. 18. Mucosa B. Lamina propria Loose areolar connective tissue Capillaries for nourishment and absorption Lymphoid follicles (part of MALT) C. Muscularis mucosae: smooth muscle that

produces local movements of mucosa ??? Copyright 2011 Pearson Education, Inc. 19. 2. Submucosa Submucosa Dense connective tissue ??? Blood and lymphatic vessels, lymphoid follicles, and submucosal nerve plexus ??? Copyright 2011 Pearson Education, Inc. 20.

3. Muscularis Externa Responsible for segmentation and peristalsis Inner circular and outer longitudinal layers Myenteric nerve plexus ??? Sphincters in some regions Copyright 2011 Pearson Education, Inc. 21. 4. Serosa Visceral peritoneum Replaced by the fibrous adventitia in the esophagus skip Retroperitoneal organs have both an adventitia and serosa skip Copyright 2011 Pearson Education, Inc.

22 Fig. 23.6 page 857 Nerve Artery Vein Mesentery Copyright 2011 Pearson Education, Inc. Intrinsic nerve plexuses Myenteric nerve plexus Submucosal nerve plexus Glands in submucosa Mucosa Epithelium Lamina propria Muscularis mucosae Submucosa

Muscularis externa Longitudinal muscle Circular muscle Serosa Epithelium Connective tissue Lumen Gland in mucosa Lymphatic Mucosa-associated Duct of gland outside vessel lymphoid tissue alimentary canal Figure 22.6 23.

Enteric Nervous System Intrinsic nerve supply of the alimentary canal Submucosal nerve plexus Regulates glands and smooth muscle in the mucosa Myenteric nerve plexus Controls GI tract motility Copyright 2011 Pearson Education, Inc. 24. Enteric Nervous System Linked to the CNS via afferent visceral fibers Long ANS fibers synapse with enteric plexuses Sympathetic impulses inhibit secretion and

motility Parasympathetic impulses stimulate Copyright 2011 Pearson Education, Inc. 25. Mouth Oral (buccal) cavity Bounded by lips, cheeks, palate, and tongue Oral orifice is the anterior opening Lined with stratified squamous epithelium Copyright 2011 Pearson Education, Inc. Soft palate Palatoglossal arch Hard palate Oral cavity Palatine tonsil Tongue Oropharynx

Lingual tonsil Epiglottis Hyoid bone Laryngopharynx 26 Uvula Fig. 23.7a Page 857 Palantine bone Palantine process of maxillla Esophagus Trachea (a) Sagittal section of the oral cavity and pharynx Copyright 2011 Pearson Education, Inc.

Figure 22.7a 27. Lips and Cheeks Contain orbicularis oris and buccinator muscles Vestibule: recess internal to lips and cheeks, external to teeth and gums Oral cavity proper lies within the teeth and gums Labial frenulum: median attachment of each lip to the gum Copyright 2011 Pearson Education, Inc. 28 Fig. 23.7b; page 859 Gingivae (gums) Palatine raphe Hard palate Soft palate Uvula Palatine tonsil

Sublingual fold with openings of sublingual ducts Vestibule Lower lip Upper lip Superior labial frenulum Palatoglossal arch Palatopharyngeal arch Posterior wall of oropharynx Tongue Lingual frenulum Opening of submandibular duct Gingivae (gums) Inferior labial

frenulum (b) Anterior view Copyright 2011 Pearson Education, Inc. Figure 22.7b 29. Palate Hard palate: palatine bones and palatine processes of the maxillae Slightly corrugated to help create friction against the tongue Soft palate: fold formed mostly of skeletal muscle Closes off the nasopharynx during swallowing Uvula projects downward from its free edge

Copyright 2011 Pearson Education, Inc. 30. Tongue Functions include Repositioning and mixing food during chewing Formation of the bolus Initiation of swallowing, speech, and taste Intrinsic muscles change the shape of the tongue Extrinsic muscles alter the tongues position Lingual frenulum: attachment to the floor of the mouth Copyright 2011 Pearson Education, Inc. 31. Tongue Surface bears papillae

taste buds Diagram Copyright 2011 Pearson Education, Inc. Epiglottis Palatopharyngeal arch Palatine tonsil Lingual tonsil cluster of lymphoid follicles Palatoglossal arch Terminal sulcus

Foliate papillae Circumvallate papilla Midline groove of tongue Dorsum of tongue 32 Fig. 23.8 Page 860 Fungiform papilla Filiform papilla Copyright 2011 Pearson Education, Inc. Figure 22.8 33.

Salivary Glands Extrinsic salivary glands (parotid, submandibular, and sublingual) Copyright 2011 Pearson Education, Inc. 34. Salivary Glands Intrinsic (buccal) salivary glands are scattered in the oral mucosa - no ducts Secretion (saliva) Cleanses the mouth Moistens and dissolves food chemicals Aids in bolus formation Contains enzymes that begin the breakdown of starch (amylase)

Copyright 2011 Pearson Education, Inc. 35. Salivary Glands Parotid gland Anterior to the ear external to the masseter muscle Parotid duct opens into the vestibule next to second upper molar Submandibular gland Medial to the body of the mandible Duct opens at the base of the lingual frenulum Copyright 2011 Pearson Education, Inc. 36. Salivary Glands

Sublingual gland Anterior to the submandibular gland under the tongue Opens via 1012 ducts into the floor of the mouth Copyright 2011 Pearson Education, Inc. 37 Fig. 23.9 page 861 Tongue Teeth Parotid gland Ducts of sublingual

gland Frenulum of tongue Sublingual gland Mylohyoid muscle (cut) Anterior belly of digastric muscle (a) Submandibular gland Parotid duct Masseter muscle Body of mandible (cut) Posterior belly of digastric

muscle Submandibular duct Mucous cells (b) Copyright 2011 Pearson Education, Inc. Serous cells forming demilunes Figure 22.9 38. Composition of Saliva

Secreted by serous and mucous cells 9799.5% water, slightly acidic solution containing Salivary amylase and lingual lipase PLAY Animation: Rotatable head Copyright 2011 Pearson Education, Inc. 39. Control of Salivation Intrinsic glands continuously keep the mouth moist Extrinsic salivary glands produce secretions when Ingested food stimulates chemoreceptors and

mechanoreceptors in the mouth - Smell Strong sympathetic stimulation inhibits salivation and results in dry mouth (xerostomia) Copyright 2011 Pearson Education, Inc. 40. Teeth Primary and permanent dentitions are formed by age 21 20 deciduous teeth erupt (624 months of age) Roots are resorbed, teeth fall out (612 years of age) as permanent teeth develop 32 permanent teeth All except third molars erupt by the end of adolescence

Copyright 2011 Pearson Education, Inc. 41 (b) Figure 23.10; page 862 Deciduous teeth Copyright 2011 Pearson Education, Inc. Permanent teeth Figure 22.10b 42. Classes of Teeth 2I, 1C, 2P, 3M

Incisors Chisel shaped for cutting Canines Fanglike teeth that tear or pierce Premolars (bicuspids) and Molars Have broad crowns with rounded cusps for grinding or crushing Copyright 2011 Pearson Education, Inc. 43 Figure 23.10; page 863 Incisors Central (68 mo) Lateral (810 mo) Canine (eyetooth)

(1620 mo) Molars First molar (1015 mo) Second molar (about 2 yr) (a) Copyright 2011 Pearson Education, Inc. Deciduous (milk) teeth Incisors Central (7 yr) Lateral (8 yr) Canine (eyetooth) (11 yr) Premolars

(bicuspids) First premolar (11 yr) Second premolar (1213 yr) Molars First molar (67 yr) Second molar (1213 yr) Third molar (wisdom tooth) (1725 yr) Permanent teeth Figure 22.10a 44.

Tooth Structure Crown: the exposed part above the gingiva (gum) Covered by enamelthe hardest substance in the body (calcium salts and hydroxyapatite crystals) Root: portion embedded in the jawbone Connected to crown by neck Copyright 2011 Pearson Education, Inc. 45. Tooth Structure Cementum: calcified connective tissue Covers root and attaches it to the periodontal ligament

Periodontal ligament Forms fibrous joint called a gomphosis Gingival sulcus: groove where gingiva borders the tooth Copyright 2011 Pearson Education, Inc. 46. Tooth Structure Dentin: bonelike material under enamel Maintained by odontoblasts of pulp cavity Pulp cavity: cavity surrounded by dentin Pulp: connective tissue, blood vessels, and nerves Root canal: extends from pulp cavity to the

apical foramen of the root Copyright 2011 Pearson Education, Inc. Crown Neck Root Enamel Dentin Dentinal tubules Pulp cavity (contains blood vessels and nerves) Gingiva (gum) Cementum 47

Root canal Periodontal ligament Figure: 23.11 Page: 863 Apical foramen Bone Copyright 2011 Pearson Education, Inc. Figure 22.11 48. Tooth and Gum Disease Skip 48 through 50 - FYI only Dental caries (cavities): gradual demineralization of enamel and dentin

Dental plaque (sugar, bacteria, and debris) adheres to teeth Acid from bacteria dissolves calcium salts Proteolytic enzymes digest organic matter Prevention: daily flossing and brushing Copyright 2011 Pearson Education, Inc. 49. Tooth and Gum Disease Gingivitis Plaque calcifies to form calculus (tartar) Calculus disrupts the seal between the gingivae and the teeth Anaerobic bacteria infect gums Infection reversible if calculus removed Copyright 2011 Pearson Education, Inc.

50. Tooth and Gum Disease Periodontitis Immune cells attack intruders and body tissues Destroy periodontal ligament Activate osteoclasts Consequences Possible tooth loss, promotion of atherosclerosis and clot formation in coronary and cerebral arteries Copyright 2011 Pearson Education, Inc.

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