Transcript Anatomy & Physiology SIXTH EDITION Chapter 24, part 3 The Digestive System PowerPoint® Lecture Slide Presentation prepared by Dr.

Anatomy & Physiology
SIXTH EDITION
Chapter 24, part 3
The Digestive System
PowerPoint® Lecture Slide Presentation prepared by
Dr. Kathleen A. Ireland, Biology Instructor, Seabury Hall, Maui, Hawaii
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Frederic H. Martini
Fundamentals of
Histology of the stomach
• Gastric glands
• Parietal cells
• Intrinsic factor, and HCl
• Chief cells
• Pepsinogen
• Pyloric glands
• Mucous secretion containing several hormones
• Enteroendocrine cells
• G cells secrete gastrin
• D cells secrete somatostatin
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Figure 24.13 The Stomach Lining
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Figure 24.13a, b
Figure 24.13 The Stomach Lining
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Figure 24.13c, d
Figure 24.14 The Secretions of Hydrochloric
Acid
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Figure 24.14
Regulation of gastric activity
• Cephalic phase prepares stomach to receive
ingested material
• Gastric phase begins with the arrival of food in
the stomach
• Neural, hormonal, and local responses
• Intestinal phase controls the rate of gastric
emptying
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Figure 24.15 The Phases of Gastric Secretion
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Figure 24.15a
Figure 24.15 The Phases of Gastric Secretion
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Figure 24.15b
Figure 24.15 The Phases of Gastric Secretion
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Figure 24.15c
Digestion and absorption in the stomach
• Preliminary digestion of proteins
• Pepsin
• Permits digestion of carbohydrates
• Very little absorption of nutrients
• Some drugs, however, are absorbed
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SECTION 24-6
The Small Intestine and Associated Glandular
Organs
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Small intestine
• Important digestive and absorptive functions
• Secretions and buffers provided by pancreas,
liver, gall bladder
• Three subdivisions:
• Duodenum
• Jejunum
• Ileum
• Ileocecal sphincter
• Transition between small and large intestine
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Figure 24.16 Regions of the Small Intestine
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Figure 24.16a
Histology of the small intestine
• Plicae
• Transverse folds of the intestinal lining
• Villi
• Fingerlike projections of the mucosa
• Lacteals
• Terminal lymphatic in villus
• Intestinal glands
• Lined by enteroendocrine, goblet and stem
cells
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Figure 24.17 The Intestinal Wall
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Figure 24.17a
Figure 24.17 The Intestinal Wall
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Figure 24.17b, c
Figure 24.17 The Intestinal Wall
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Figure 24.17d, e
Intestinal juices
• Moisten chyme
• Help buffer acids
• Maintain digestive material in solution
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Small Intestine
• Duodenal glands (Brunner’s glands)
• produce mucus, buffers, urogastrone
• Ileum
• aggregated lymphoid nodules (Peyer’s patches)
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Intestinal movements
• Peristalsis
• Segmentation
• Gastroenteric reflexes
• Initiated by stretch receptors in stomach
• Gastroileal reflex
• Triggers relaxation of ileocecal valve
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The pancreas
• Pancreatic duct penetrates duodenal wall
• Endocrine functions
• Insulin and glucagons
• Exocrine functions
• Majority of pancreatic secretions
• Pancreatic juice secreted into small intestine
• Carbohydrases
• Lipases
• Nucleases
• Proteolytic enzymes
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Figure 24.18 The Pancreas
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Figure 24.18a-c