The Digestive System and Body Metabolism 14 The Digestive System and Body Metabolism

CH 14 THE DIGESTIVE SYSTEM I. Overview Of The Digestive System: Functions B. Major Processes Ingestion Digestion Absorption Defecation C. Organs Alimentary Canal Accessory Digestive Organs Sphincters

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

II. Organs of the Digestive System A. Alimentary Canal Organs. 1 II. Organs of the Digestive System A. Alimentary Canal Organs 1. Mouth (Oral Cavity) a. Anatomy Oral cavity proper—area contained by the teeth Uvula—fleshy projection of the soft palate - Function Tongue Tonsils

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

iv) Chemical Digestion: b. Mouth Physiology i) Mastication: Mixing with saliva ii) Swallowing: iii) Taste iv) Chemical Digestion: Enzyme: Amylase + Starch Glucose + Glucose …

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)

b. Pharynx Physiology passageway for air and food to Esophagus How keep food out of Lungs– see Respiratory system-Larynx

3. Esophagus Anatomy b. Location: c. Functions

4. Stomach a. Anatomy Shape Smooth muscle in Walls– 3 layers Cardioesophageal Sphincter 4. Stomach a. Anatomy Shape Smooth muscle in Walls– 3 layers Rugae—internal folds of the mucosa can hold 4 L (1 gallon) Inner Tissue (lining): Microscopic- Gastric Glands Location: Sphincters Cardioesophageal Pyloric Pyloric Sphincter Rugae Gastric Glands

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

Fundus Body Rugae of mucosa Pyloric (b) Pyloric sphincter antrum Figure 14.4b

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

b. Stomach Physiology i) Temporary storage ii) Digestion of Proteins Gastric glands— secrete gastric juice which contains: - Hydrochloric Acid (HCl): produced by Parietal cells - Pepsinogen: inactive form of enzyme; produced by Chief cells Pepsin: activated form of enzyme Pepsinogen; activated by HCl Chief Cells Parietal Cells Pepsinogen Gastric Glands Pepsin HCl

Pepsin digests Proteins into its subunits, Amino Acids Pepsin + Proteins Amino Acids + A.A. …

5. Small Intestine a. Anatomy i) Gross Gross View a. Anatomy i) Gross (1) Shape: Tubular; ??? Long, ?? wide (2) Smooth Muscle: two layer (3) Inner folds Function ii) Microscopic Anatomy (1) Tissue of Lining: (2) Villi: Blood vessels Lacteal Microvilli Microscopic view of Villi Microvilli

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

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

Microvilli (brush border) (c) Absorptive cells Figure 14.7c

b. Subdivisions of the Small Intestine i) Duodenum location - Curves around Receives substances from Pancreas: Pancreatic Duct - Liver: ii) Jejunum iii) Ileum

c. Physiology-Functions Chemical Digestion Absorption i) Chemical digestion Enzymes for all nutrient types: - Intestinal cells - Pancreas Nutrients– broken down into: - Carbohydrates  - Proteis  - Fats  - Nucleic Acids are broken down into 

ii) Emulsification of lipids with Bile: iii) Absorption of Nutrients Subunits absorbed by cells lining intestine. - Then into capillaries - Fat components via Lacteal The Hepatic Portal Artery takes blood with nutrients to Liver for detoxification. Only afterwards does the blood go back to Heart.

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

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

Large Intestine Anatomy … i) Appendix lymphatic tissue that sometimes becomes inflamed (appendicitis) ii) Colon Ascending Transverse Descending—travels down the left side Sigmoid iii) Anus—inferior opening

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

Large Intestine Physiology c. Physiology– FUNCTIONS Digestive enzymes: Resident bacteria: Produce: Release gases Absorption of: Formation & Elimination of Feces

B. Accessory Digestive OrgansTeeth 1. Salivary Glands Saliva composition: Mucus and serous fluids salivary amylase: Functions

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

Location: Digestive products: secreted into: Hormones Function: 2. Pancreas Location: Digestive products: secreted into: Hormones Function: Insulin: Glucagon: Duodenum Pancreas

3. Liver Location: Connected to: Lobes Produces BILE: Bile salts & Pigments Cholesterol Phospholipids Electrolytes Depositied in: Function Liver Pancreas Gallbladder

Diaphragm Falciform ligament Liver Spleen Gallbladder Stomach Greater omentum Small intestine Large intestine Cecum (a) Figure 14.5a

4. Gallbladder Sac under liver Function: Bile released when:

III. Functions of the Digestive System-- Summarization A. Ingestion: Propulsion Peristalsis Segmentation— B. Mechanical digestion Teeth tongue stomach

Functions of the Digestive System C. Chemical digestion Mouth, Stomach, Small Intestine D. Absorption Most Nutrients: Water: small and large intestine E. Defecation = Rectum & Anus

IV. Nutrition A. Introduction 1. Nutrients from food are used for: Build molecules, cells, and structures Replace worn out parts Produce metabolic Fuels: ATP for energy 2. Kilocalories (kcal): unit of measurement of energy value of food Nutrition– 6 categories of nutrients 1. Major nutrients Carbohydrates Lipids Protein Water

Minor Nutrients Vitamins Minerals Five Food Groups Grains Fruits Vegetables Meats & Fish Milk products

C. Dietary Sources of the Major Nutrients 1. Carbohydrates a. Most from plants Sugars: fruits & sugar cane Starch: Grains, Legumes, Root vegetables Cellulose b. Lactose from milk c. glycogens from meats 2. Lipids a. Triglycerides (fats) are mostly the lipid in our food Saturated fats: animal products & coconut Unsaturated fats: plants as seeds, nuts, vegetable oils Trans fats: “hydrogenated”

Proteins b. Cholesterol: egg yolk, meats, & milk products 2. Lipids … b. Cholesterol: egg yolk, meats, & milk products Proteins a. Complete Proteins Animal Products Essential amino acids: 8 amino acids we can not make b. Incomplete proteins Plants: cereals, nuts, & legumes Are low in one or more essential amino acids Must eat combinations of different types: Example: cereal grains & legumes– rice & beans Corn & Beans

D. Dietary Sources of Minor Nutrients Vitamins Must eat Combinations: No one food has all of the required vitamins Cancer: Some protect against cancer (anti-oxidants) Crucifer Vegetables: Broccoli, Cabbage, Brussel Sprouts: Vitamins A and C Coenzymes: Function with Enzymes to complete chemical reactions Minerals Are components of Proteins, Hormones, Enzymes and Vitamins Examples: 1) Iron in Hemoglobin attaches to the O2 2) Iodine is a component of Thyroid Hormone

V. Metabolism Carbohydrates mainly used to make ATP Glucose: a. Blood Sugar = Glucose b. Carbohydrate Digestion: Major breakdown product c. Cellular Respiration: Major fuel used for making ATP; requires O2 Blood Sugar Homeostasis: Insulin & Glucagon i) Hyperglycemia First stored as glycogen in liver and muscles Then converted to fat ii) Hypoglycemia Liver: breaks down glycogen into glucose Fats: can be used to generate ATP

Fats mainly used to make other required lipid Liver used them to synthesize Lipoproteins, Clotting Proteins, & Cholesterol Fats also released into blood by Liver: Then cells take fats inside and make: Cell membranes (phospholipids) Steroid hormones Myelin sheath of neurons Fatty cushions around certain organs, like heart Excess amounts stored as Adipose connective tissue: Equal amounts of glucose and fats, fats yield twice as much energy

C. Protein Metabolism Liver processes digestive products before they circulate to the body; uses amino acids to make plasma proteins … Cells use active transport processes to take amino acids inside (requires ATP) They must have all 8 essential amino acids and the 12 others that cells can make in order to make any type of protein Amino Acids used to produce ATP: Only under extreme conditions, like starvation The nitrogen-containing portion is converted to Ammonia, which is toxic to neurons Liver converts Ammonia into Urea which is removed in the urine

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