Digestive System 1

Digestive system 2

Food Intake - Ingestion

Digestive Process 1.Ingestion 2. Peristalsis 3. Digestion 4. Absorption 5. Defication 4

Digestion: The breaking down of food molecules 1. mechanical digestion – 2.Chemical digestion – 5

Composition Main Organs – Accessory Organs – Length – 6

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Structure Lumen – Digestive Wall – 4 layers – Mucosa or mucous membrane – Submucosa – Muscularis – Serosa Peritoneum 8

Mucosa Inner layer composed of – Surface Epithelium – – Lamina Propria – – Musculari mucosa – 9

Submucosa Contains: – 10

Muscularis Consists of – contractions help break down food physically, mix it with… 11

Serosa Outermost layer Composed of … AKA: the visceral peritoneum 12

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Peritoneum Serous Membrane – Parietal peritoneum: – Visceral peritoneum: – Peritoneum forms… 14

Important folds of the peritoneum Mesentary- Falciform ligament- Lesser omentum- Greater Omentum – 15

Mouth Oral or buccal cavity formed by… Cheeks – Lips – 16

Mouth cont. Vestibule – Roof of Mouth – Hard palate – – Soft palate – – Uvula – 17

Tongue Forms the floor of the oral cavity; skeletal muscle Extrinsic muscle – Intrinsic muscles – 18

Tongue cont. Lingual Frenulum – Papillae – Taste Buds - 19

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Salivary glands 3 pairs of glands that produce saliva – Parotid – mumps – 21

Salivary Glands cont. Submandibular – Sublingual – 22

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Composition of Saliva continuously secreted by salivary glands secretion increases when… Volume: in 24 hours… – 99.5% H20 solvent + mucin = mucous – 0.5% solutes Usually controlled by… 24

0.5% of solutes Salts – Some organic compounds Mucin- Salivary amylase – Lysozyme – 25

Teeth Dentition Typical tooth consists of – Crown – – Root – – Cervix or neck – 26

Teeth Composition – Dentin: – Pulp cavity: 27

Teeth Composition cont. – Root canals: – Enamel: 28

Tooth Dentitions: 2 sets of teeth – Decidnous, Incisors – Cuspids(canines) – First and second molars – – Permanent teeth (23) Incisors (8) Cuspids (4) Bicuspids (8) Molars (12) first second and third (wisdom teeth) 29

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Digestion in Mouth Mechanical – Chemical – 31

Swallowing or Deglutition Moves food from mouth to stomach in 3 phases – Volutary stage: – Pharyngual stage: – Esophagual stage: 32

Esophagus A muscular, collapsible tube that lies behind the trachea and is about 10 inches long, that connects the pharynx to the stomach; leaves thoracic cavity through opening in diaphragm esophageal hiatus 33

Esophagus cont. No enzyme secretion or absorption Secretes… Passage of food is regulated sphincters – 34

Stomach J-shaped enlargement of the digestive tract; the superior portion is a continuation of the esophagus as the inferior portion connects to the duodenum Function – Primary - – Secondary - 35

Stomach Anatomy – Cardia - – Fundus – – Body – – Pylorus – 36

Stomach Wall made of 4 layers with certain modifications – Mucosae – large folds-rugae; composed of – Gastric Pits – Zymogenic (chief) cells: Parietal cells: 37

Stomach – Gastric pits Parietal cells cont. – – Intrinsic factor – Mucous cells – Enteroendocrine cells – 38

Stomach – Muscularis – 3 layers These allow for mechanical digestion, mixing with gastric juices and movement of food to duodenum 39

Stomach Digestion Mechanical – Food remains in fundus … Chemical – pH of 2 Pepsin – Gastric lipase – Very little digestion of lipids in adult stomach 40

Stomach Gastric Secretion Regulation – 41

Stomach Empties contents into duodenum 2-6 hours after ingestion – CH2O – – Protein – – Fats – Absorption – 42

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Pancreas Dual-function organ – Soft oblong gland 6 inches long 1 inch think – Lies posterior to the greater curvuture of the stomach and is connected to duodenum by a duct – Divided into head, body, and tail – Islets of langerhans- – 99% of cells are… 44

Pancreas Pancreatic Juice mL per 24 hours – Clear, colorless liquid – pH – Compound mostly… – Enzymes 45

Pancreas Secretion – – Secretin – Rich in Na HCO – Cholecystokinin – 46

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Liver Located under the diaphragm and is divided into the right and left lobes by falciform ligament Common bile duct – 48

Liver Common bile duct – Hepatic duct – – Cystic duct – 49

Liver Composition – Many functional units called lobules which consist of cords of: Hepatic cells – Sinusoids – Kupffer cells – 50

Liver Blood comes from hepatic artery and hepatic portal vein Bile: – 51

Liver Bile composition – H2O – Electrolytes (dilute and help buffer acids in chyme) – Bilirubin – – Assortment of lipids – 52

Liver Function – over 200 – Manufactures bile salts – Manufactures… – Phagocytosis of… – Break down… – Forms glycogen from… – Storage of… 53

Liver Gallbladder – Stores and concentrate… – 54

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Small Intestine Majority of digestion and absorption occurs; 20 feet long and cm in diameter – Divisions Duodenum (10 inches) secretions from pncreas and liver Jejunum – 8 feet ileum 56

Small intestine Plica – Transverse folds… Each supports a series of fingerlike projections Intestinal villi - – Mucosa Contains intestinal glands – 57

Small intestine Duodenum’s submucosa contains Brunner’s glands which Chyme in small intestine 3-5 hours pH... 58

Small intestine Peyer’s patches – 59

Small intestine Chemical digestion – Table 14-2 – CH2O – – Proteins – – Lipids – – Nucleic Acids – 60

Small intestine Absorption – – Diffusion, facilitated diffusion, osmosis, active transport 61

Large Intestine “Colon” 5 feet in length x 2.5 inches wide; no villi, still have microvilli on exposed surfaces of epithelium – Functions 62

Large Intestine 4 regions, ascending colon starts – ileocecal valve controls passage of chyme ito cecum – Cecum (3 in) - – Colon – – Rectum (8 in) – Anal canal (1 in) 63

Large intestine Movement of Chyme 3-10 hours – Peristalsis – Mass peristalsis – – Bacterial digestion – – – Chyme – 64

Large intestine Feces composition – 65

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