Digestive System
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45 terms
Terms | Definitions |
|---|---|
 Digestion | the mechanical and chemical breakdown of foods and the absorption of the resulting nutrients by cells. |
| Functions of Digestion | ingestion; mechanical digestion; chemical digestion; propulsion; absorption; defecation |
| Ingestion | Consume Nutrients. |
| Mechanical Digestion | Break food without altering chemical make-up. |
| Chemical Digestion | Break food into simpler compounds. |
| Propulsion | Peristalsis |
| Salivary Glands | Secrete saliva which contain enzymes that initiate breakdown of accessory carbohydrates. |
| Liver | Produces bile, which emulsifies fat. |
| Gallbladder | Stores bile and introduces it to the small intestine. |
| Pancreas | Produces and secretes pancreatic juice,containing digestive enzymes and bicarbonate ions, into small intestines. |
| Mouth | Mechanical breakdown of food; begins chemical digestion of carbohydrates. |
| Pharynx | Connects mouth with esophagus. |
| Esophagus | Peristalsis pushes food to stomach. |
| Stomach | Secretes acid and enzymes. Mixes food with secretions to begin enzymatic digestion of proteins. |
| Small Intestine | Mixes food with bile and pancreatic juice. Final enzymatic breakdown of food molecules, main site of nutrient absorption. |
| Large Intestine | Absorbs water and electrolytes to form feces. |
| Rectum | Regulates elimination of feces. |
| Mouth | ingestion; mechanical digestion; prepares food for chemical digestion. |
| Tongue | Mix food particles with saliva during chewing; Move food to pharynx during swallowing. Also, helps to move food under teeth for chewing. Papillae help handle and taste food. |
| Palate | Roof of oral cavity |
| Secretions of Salivary Glands | Parotoid glands (Largest); Submandibular glands; Sublingual glands (Smallest) |
| Parotoid Glands | (Largest), Secretion of salivary glands: • clear • water, serous fluid • rich in amylase |
| Submandibular Glands | Secretion of salivary glands: • Primarily serous fluid • some mucus |
| Sublingual Glands | (Smallest), Secretion of salivary glands: • primarily mucus • thick and stringy |
| Pharynx | • A cavity posterior to the mouth from which the tubular esophagus leads to the stomach. • Does not digest food. • Three parts: • nasopharyhnx • oropharynx • laryngopharynx |
| Swallowing Mechanism | • soft palate and uvula raise - preventing food from entering the nasal cavity. • hyoid bone and larynx elevate. • epiglottis closes off top of trachea. • longitudinal muscles of pharynx contract. • inferior constrictor muscles relax and esophagus opens • peristaltic waves push food through pharynx. • The tongue is pressed against the soft plate, sealing off the oral cavity from the pharynx. |
| Stomach | Inferior to the diaphram, holds about 1liter or more. |
| Lining of the Stomach | Thick; Studded with gastric pits which are ends of tubular gastric pits |
| Gastric Secretions | pepsinogen, pepsin, hydrochloric acid, mucus, intrinsic factor. |
| Pepsinogen | From chief cells; inactive form of pepsin. |
| Pepsin | From pepsinogen in presence of HCl; protein splitting enzyme. |
| Hydrochloric Acid | From parietal cells; needed to convert pepsinogen to pepsin. |
| Mucus | From goblet cells and mucous glands, protective to stomach wall. |
| Intrinsic Factors | From parietal cells, required for vitamin B12 absorption. |
| Phases of Gastric Secretion | Cephalic Phase, Gastric Phase, Intestinal Phase |
| Cephalic Phase | Phase of Gastric Secretion • triggered by smell, taste, sight, or thought of food • parasympathetic impulses trigger gastric juice secretion |
| Gastric Phase | Phase of Gastric Secretions • triggered by presence of food in stomach • gastrin released • gastric juice secreted |
| Intestinal Phase | Phase of Gastric Secretion • triggered by movement of food into small intestine • intestinal cells release intestinal gastrin • secretion of gastric juice |
| Gastric Absorption | Some water, certain salts, certain lipid-soluble drugs, alcohol. |
| Pancreatic Juice | pancreatic amylase; pancreatic lipase; trypsin, chymotrypsin, and carboxypeptidase; nucleases; bicarbonate ions. |
| pancreatic amylase | Type of pancreatic juice; splits glycogen into disaccharides. |
| pancreatic lipase | type of pancreatic juice; breaks down triglycerides. |
| nucleases | type of pancreatic juice; digest nucleic acids. |
| bicarbonate ions | type of pancreatic juice; make pancreatic juice alkaline. |
| digest proteins | trypsin, chymotrypsin, and carboxypeptidase. |
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