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The Digestive System and Body Metabolism
14 The Digestive System and Body Metabolism
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I. The Digestive System Functions-- Overview
Major Processes Ingestion Digestion Absorption Defecation
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II. Organs of the Digestive System
Two main groups of organs Alimentary canal = gastrointestinal: Mouth, Pharynx, Esophagus, Stomach, Small intestine, Large intestine, Anus Accessory digestive organs: liver, pancreas, gall bladder Other: sphincters
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Mouth (oral cavity) Parotid gland Tongue Sublingual gland Salivary glands Submandibular gland Pharynx Esophagus Stomach Pancreas (Spleen) Liver Gallbladder colon Transverse Duodenum Descending colon Small intestine Jejunum lleum Ascending colon Large intestine Cecum Sigmoid colon Rectum Appendix Anus Anal canal Figure 14.1
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A. Alimentary Canal Organs 1. Mouth (Oral Cavity) Anatomy
a. Anatomy Oral cavity proper—area contained by the teeth Uvula—fleshy projection of the soft palate Function Tongue Tonsils
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Nasopharynx Hard palate Soft palate Oral cavity Uvula Lips (labia)
Palatine tonsil Vestibule Lingual tonsil Oropharynx Lingual frenulum Epiglottis Tongue Laryngopharynx Hyoid bone Esophagus Trachea (a) Figure 14.2a
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Chemical Digestion of ______________ using
b. Mouth Physiology Mastication= Mixing with saliva Swallowing: taste Chemical Digestion of ______________ using enzyme __________________ Amylase + Starch Glucose + Glucose …
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2. Pharynx a. Anatomy: see Respiratory System iAnatomy– see Ch 13
Nasopharynx Hard palate Soft palate Oral cavity Uvula Lips (labia) Palatine tonsil Vestibule Lingual tonsil Oropharynx Lingual frenulum Epiglottis Tongue Laryngopharynx Hyoid bone Esophagus Trachea (a)
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b. Pharynx Physiology passageway for air and food to Esophagus
How keep food out of Lungs?
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3. Esophagus a. Anatomy b. Location: c. Functions
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Diaphragm Falciform ligament Lesser omentum Liver Spleen Pancreas Gallbladder Stomach Duodenum Visceral peritoneum Transverse colon Greater omentum Mesenteries Parietal peritoneum Small intestine Peritoneal cavity Uterus Large intestine Cecum Rectum Anus Urinary bladder (a) (b) Figure 14.5
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4. Stomach a. Anatomy Location: Cardioesophageal Sphincter
Rugae—internal folds of the mucosa can hold 4 L (1 gallon) Inner Tissue: Smooth muscle in Walls-- 3 Food leaves to _________ pyloric sphincter (valve)
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Cardioesophageal sphincter Fundus Esophagus Muscularis externa Serosa
• Longitudinal layer • Circular layer Body • Oblique layer Lesser curvature Rugae of mucosa Pylorus Greater curvature Duodenum Pyloric Sphincter (valve) Pyloric antrum (a) Figure 14.4a
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Fundus Body Rugae of mucosa Pyloric (b) Pyloric sphincter antrum
Figure 14.4b
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Diaphragm Falciform ligament Liver Spleen Gallbladder Stomach
Greater omentum Small intestine Large intestine Cecum (a) Figure 14.5a
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Diaphragm Lesser omentum Liver Pancreas Duodenum Stomach
Visceral peritoneum Transverse colon Greater omentum Mesenteries Parietal peritoneum Small intestine Peritoneal cavity Uterus Rectum Anus Urinary bladder (b) Figure 14.5b
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b. Stomach Physiology Temporary storage Digestion of Proteins
Gastric glands— secrete gastric juice Chief cells—produce pepsinogen = ? Parietal cells—produce hydrochloric acid = ?
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Digestion of Proteins …
Pepsinogen activated how? Pepsin digests ___________ into subunits = _______________ Pepsinogen Pepsin HCl Pepsin + Proteins Amino Acids + A.A. …
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Pepsinogen Pepsin HCl Parietal cells Chief cells (d)
Enteroendocrine cell (d) Figure 14.4d
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5. Small Intestine a. ANATOMY
Muscular tube extends from ________ to _______ Receives substances needed from:
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Anatomy … Microscopic Anatomy Villi = ? Blood vessels Lacteal
Tissue of inner lining = ? Microvilli: _________ Function: _________
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b. Subdivisions of the Small Intestine
Duodenum location Curves around ________ Receives substances from Pancreas:_____________ via Pancreatic Duct - Liver: _____________ Jejunum Ileum Extends to ______________
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Chemical Digestion in the Small Intestine
c. FUNCTIONS Chem Digestion Absorption i) Chemical digestion Enzymes for all nutrient types: Intestinal cells Pancreas Nutrients: Carbohydrates, Proteis, Fats, Nucleic Acids are broken down into
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ii) Emulsification of lipids with Bile:
Helps Enzymes by: ________________ Gall Bladder: ________________
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iii) Absorption of Nutrients
Subunits absorbed by cells lining intestine. Then into capillaries Fat components via Lacteal The Liver– why? Food Food
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Bile duct and sphincter Accessory pancreatic duct
Right and left hepatic ducts from liver Cystic duct Common hepatic duct Bile duct and sphincter Accessory pancreatic duct Pancreas Gallbladder Jejunum Duodenal papilla Hepatopancreatic ampulla and sphincter Main pancreatic duct and sphincter Duodenum Figure 14.6
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Lumen Villi (a) Small intestine
Blood vessels serving the small intestine Lumen Muscle layers Circular folds (plicae circulares) Villi (a) Small intestine Figure 14.7a
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Lacteal Villus (b) Villi
Absorptive cells Lacteal Villus Blood capillaries Lymphoid tissue Intestinal crypt Muscularis mucosae Venule Lymphatic vessel Submucosa (b) Villi Figure 14.7b
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Microvilli (brush border) (c) Absorptive cells Figure 14.7c
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Goblet cells produce mucus for ________ b. Subdivisions: Cecum
6. Large Intestine a. ANATOMY Larger diameter Extends to anus No villi present Goblet cells produce mucus for ________ b. Subdivisions: Cecum Appendix Colon Rectum Anal canal
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Large Intestine Anatomy
Appendix lymphatic tissue that sometimes becomes inflamed (appendicitis) Colon Ascending Transverse Descending—travels down the left side Sigmoid Anus—inferior opening
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External anal sphincter
Left colic (splenic) flexure Transverse mesocolon Right colic (hepatic) flexure Transverse colon Haustrum Descending colon Ascending colon IIeum (cut) Cut edge of mesentery IIeocecal valve Teniae coli Sigmoid colon Cecum Appendix Rectum Alan canal External anal sphincter Figure 14.8
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Large Intestine Physiology
c. FUNCTIONS Digestive enzymes: Resident bacteria: Produce: Release gases Absorption of: Formation & Elimination of Feces
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B. Accessory Digestive OrgansTeeth
1. Salivary Glands Saliva composition: Mucus and serous fluids salivary amylase: Functions
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Bile duct and sphincter Accessory pancreatic duct
Right and left hepatic ducts from liver Cystic duct Common hepatic duct Bile duct and sphincter Accessory pancreatic duct Pancreas Gallbladder Jejunum Duodenal papilla Hepatopancreatic ampulla and sphincter Main pancreatic duct and sphincter Duodenum Figure 14.6
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2. Pancreas Location: _________ Digestive products: secreted into:
Hormones Function: _____ Insulin: __________ Glucagon: ___________ Duodenum Pancreas
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3. Liver Location: Connected to: Lobes Produces BILE:
Bile salts & Pigments Cholesterol Phospholipids Electrolytes Depositied in: Function Pancreas Gallbladder
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Diaphragm Falciform ligament Liver Spleen Gallbladder Stomach Visceral peritoneum Greater omentum Parietal peritoneum Small intestine Uterus Large intestine Cecum Urinary bladder (a) Figure 14.5a-b
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4. Gallbladder Sac under liver Function: Bile released when:
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III. Functions of the Digestive System-- Summarization
Ingestion: Propulsion Peristalsis Segmentation— Mechanical digestion Teeth tongue stomach
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Functions of the Digestive System
Chemical digestion Mouth, Stomach, Small Intestine Absorption Most Nutrients: Water: small and large intestine Defecation = Rectum & Anus
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IV. Nutrition Major nutrients C L P Water Functions Minor nutrients V
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Dietary Sources of Major Nutrients
Carbohydrates plants lactose from milk glycogens from meats Lipids Saturated fats: Unsaturated fats: Trans fats: “hydrogenated” Cholesterol from egg yolk, meats, and milk products
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Dietary Sources of Major Nutrients
Proteins Essential amino acids Complete proteins animal products Incomplete proteins plants
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V. Digestive Problems– Students do
Gastroenteritis Appendicitis Ulcers Hyperglycemia = Hypoglycemia =
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END
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Upper lip Gingivae (gums) Hard palate Soft palate Uvula
Palatine tonsil Oropharynx Tongue (b) Figure 14.2b
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Gastric pits Gastric pit Gastric gland (c)
Surface epithelium Gastric pit Pyloric sphincter Mucous neck cells Parietal cells Gastric gland Gastric glands Chief cells (c) Figure 14.4c
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Enamel Crown Dentin Pulp cavity Gum (gingiva) Neck Periodontal
membrane Bone Root Cement Root canal Blood vessels and nerves in pulp Figure 14.10
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Figure 14.12a-b
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Ingestion Food Mechanical digestion Pharynx Chewing (mouth) Esophagus Churning (stomach) Propulsion Segmentation (small intestine) Swallowing (oropharynx) Chemical digestion Peristalsis (esophagus, stomach, small intestine, large intestine) Stomach Absorption Lymph vessel Small intestine Blood vessel Large intestine Mainly H2O Feces Anus Defecation Figure 14.11
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