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Digestive System Unit Review Packet *You should study your digestive system notes, this packet, warm-ups and homework* 1) Explain the difference between digestion and metabolism: i. Digestion: 1. Breakdown of ingested food 2. Absorption of nutrients into the blood ii. Metabolism: 1. Production of cellular energy (ATP) 2. Constructive cellular activities 2) What makes up the digestive system: a. Alimentary canal: i. Mouth, Pharynx, Esophagus, Stomach, Small intestine, Large intestine, Rectum, and Anus b. Accessory organs: i. Gallbladder, Pancreas, Liver, and Salivary glands 3) Digestive Activities of the Mouth a. What is the function of saliva? i. - Mixture of mucus and serous fluids ii. Helps to form a food bolus iii. Contains salivary amylase to begin starch digestion iv. Dissolves chemicals so they can be tasted b. Mastication: (chewing) of food & Mixing with saliva c. Mechanical breakdown - Food is physically broken down by chewing d. Chemical digestion : i. Food is mixed with saliva ii. Breaking down of starch into simple sugars by salivary amylase 4) Digestive Activities of the Esophagus (FOOD TUBE) a. Runs from pharynx to stomach through the diaphragm b. Passageway for food only c. Peristalsis: (slow rhythmic squeezing) i. Moves the bolus toward the stomach. The cardioesophageal sphincter is opened when food presses against it. 1. Bolus: Mass of food and saliva 5) Digestive Activities of the Stomach a. Food enters at the Cardioesophageal Sphincter i. Acid Reflux: Malfunction of Cardioesophageal Sphincter. Chyme splashes back into esophagus. b. Chyme: processed food mixed with stomach acid and enzymes c. Chemical Digestion: Chemical breakdown of proteins begins d. Mechanical Digestion: Churning (peristalsis) of food breaks into smaller piece e. Internal anatomy of the stomach: i. Rugae : internal folds of the mucosa ii. Mucous neck cells – produce a sticky alkaline (basic) mucus (prevents stomach from digesting itself. iii. Gastric glands – secrete gastric juice (regulated by Gastrin) iv. Chief cells – produce protein-digesting enzymes (pepsinogens) v. Parietal cells – produce hydrochloric acid (pH=2) which activates the release of pepsinogens (turns into pepsin) and creates a hostile environment for microorganisms. vi. Endocrine cells – produces Gastrin which activates the release of hydrochloric acid. 1. Gastrin: Presence of food or falling pH causes the release of gastrin which causes stomach glands to produce protein-digesting enzymes (Pepsin). **The only absorption that occurs in the stomach is of alcohol and aspirin** f. Gastric (stomach) Ulcer: Can be caused by excessive stress, alcohol use, or bacteria. Stress and alcohol cause a greater amount of hydrochloric acid to be released from the Parietal cells and less mucus to be secreted from the Mucous neck cells. i. Symptoms: Abdominal pain, dark stools, burning. g. Pyloric Sphincter: Connects stomach to small intestine 6) Digestion and Absorption in the Small Intestine: (Digestion of food ends here) a. Small Intestine: Muscular tube extending from the pyloric sphincter to the ileocecal valve. b. Three sections of the Small Intestine: (D.J. Ileum) i. Duodenum - Attached to the stomach at the Pyloric Sphincter. Area where enzymes are added to small intestine from gallbladder and pancreas. ii. Jejunum- middle section iii. Ileum- from jejunum to large intestine c. Villi: Fingerlike structures formed by the mucosa i. Function: Give the small intestine more surface area in order to increase absorption of nutrients and water. 1. Substances are transported directly to the liver by the hepatic portal vein. 7) Digestive Activities of the Accessory Organs: a. Liver: Produces bile which is sent to the gallbladder via the common hepatic duct. i. What is Bile: Emulsifier that breaks fat (mechanically) into smaller droplets. b. Gallbladder: Stores and concentrates bile. Releases bile in the presence of fat into the Duodenum. i. Gallstones: Hard masses made from cholesterol and other things found in the bile. 1. Complications/Symptoms: Can cause a blockage in the bile duct. Bile can back up causing Jaundice (yellowing of the skin and eyes). 2. Can a person live without their Gallbladder? Explain: c. Pancreas: Produces many digestive enzymes that break down all categories of food (Lipase-break down fats, Amylase-break down starch, Trypsin and Pepsin-break down proteins). i. Enzymes are secreted into the duodenum of the small intestine. ii. Also produces an alkaline (basic) fluid to neutralize the acidic chyme. 8) Digestive Activities of the Large Intestine: a. Function: Absorption of water (slow peristalsis) i. Eliminates indigestible food from the body as feces b. Function of resident bacteria in the large intestine: i. Produce some vitamin K and B ii. Release gases c. Sections of the Large Intestine: i. Ascending colon ii. Transverse colon iii. Descending colon iv. Sigmoid colon v. Rectum vi. Anus d. Presence of feces in the rectum causes a defecation reflex i. Internal anal sphincter is relaxed ii. Defecation occurs with relaxation of the voluntary (external) anal sphincter 1. How is this important when “potty training” children? The child has to learn to recognize the signal from the defecation reflex that relaxes the internal anal sphincter. They then have to learn to control the external anal sphincter until they are at the proper place to release feces.