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3.6.4 Define denaturation •A change in the shape of a protein. Shape is everything to an enzyme. Change the shape, and the enzyme doesn’t work. (Enzymes are specific to a substrate and the active site has a distinct shape.) –Temperatures or pH changes affect the shape of an enzyme 3.6.5 Explain the use of lactase in the production of lactose-free milk •World-wide, 70% of adults are lactose intolerant. Normally, Lactose glucose +galactose. Dairy industry can add Lactase to milk and convert all of the lactose. Bonnie Blair accomplishments Digestion Section by section! (The underlined Words are very Important) Oral Cavity/Mouth 1. Food broken mechanically by teeth. (Mastication) 2. Salivary amylase in saliva breaks down starch. David J. (’04) did a spit/raw potato enzyme lab that was messy yet effective… 3. ‘Food ball’ named ‘bolus’. Pharynx to esophagus 1. Epiglottis closes over the larynx. So that food does not get into the lungs 2. Bolus travels down the esophagus by paristalsis. To the stomach 1. Bolus goes through the cardiac sphincter (sphincter near the heart –leaky sphincter here gives you heartburn! Because it lets gastric juice burns the esophagus.) 2. Gastric juice (made of pepsin and hydrochloric acid) hydrolyzes protein –breaks down protein. 3. ‘Bolus’ name changes to ‘chyme’ Review: • What gets digested in the mouth? What is the enzyme that does it? Carbohydrate, amylase • What gets digested in the stomach? What is the enzyme that does it? Protein, pepsin To the small intestines! 1. Chyme leaves the stomach through the pyloric sphincter. 2. Three hormones are secreted depending on the type of chyme: 1. Secretin stimulates the release of sodium bicarbonate from the pancreas. (makes the pH rise! Why is this important?) 2. Cholesystokinin stimulates the release of bile from the liver. Bile breaks up fats. 3. Enterogastrone slows the rate of digestion if there is a lot of fat or protein in the diet. LE 21-11a Liver Bile Gallbladder Stomach Bile Acid chyme Intestinal enzymes Duodenum of small intestine Pancreatic juice Pancreas Review: • What hormone gets secreted after a high fat meal? Cholesystokinin –stimulates the liver to secrete bile • What hormone gets secreted if the chyme is full of acid? secretin • What hormone gets secreted if the meal is large and full of protein or fat? (Slows digestion…) Enterogasterone In the Duodenum of the Small Intestine 1. Bile is secreted from the liver/gall bladder to emulsify fat… 2. Pancreatic amylase is secreted from the pancreas (for carbohydrates.) 3. Trypsin, chymotrypsin, carboxypeptidase are secreted from the pancreas for protein digestion. 4. Lipase is also secreted by the pancreas for lipid digestion. Review of stuff secreted into the small intestine: lipase • _______________ secreted by __________ pancreas to digest lipid • ______,___________,______________ Trypsin, chymotrypsin, carboxypeptidase pancreas secreted by _________ to digest protein pancreas • _____________ Pancreatic amylase secreted by the _________ to digest carbohydrate bile Liver/gall bladder • _____________ secreted by the _________ to emulsify fat Look at these important organs that secrete into the small intestine! Jejunum and Ilium of the small intestine: • This is where absorption takes place. • Villi and microvilli increase the surface area so that more absorption can take place. NOTE: Each villus is made for absorption! (lots of surface area!) Muscle layers Large circular folds Blood capillaries Nutrient absorption Lacteal Also in the Villus: • Each villus has a capillary bed and a lacteal. The capillaries get food to the circulatory system, but they are leaky! • Lacteals collect FAT and fluid that leaks out of the capillaries. elephantiasis LE 21-13a Small intestine Small intestine Stomach Cecum Colon (large Intestine) Carnivore Herbivore Large Intestine 1. 2. 3. 4. DOES NOT DIGEST Water gets reabsorbed here. Feces forms E-coli bacteria digest fiber and give off gas. That is why you give off gas. 5. E-coli bacteria also produce vitamin K from this. 6. Peristalsis occurs when the stomach expands… leads to defecation. Problems of the large intestine • Constipation: Hard, dry feces. Happens when the feces is left in the large intestine too long and too much water is reabsorbed. • Diarrhea: watery feces. Happens when there is too much peristaltic activity (infection, emotional stress, physical stress…) • Ulcerative colitis: Ulcers resulting in constant diarrhea. • Colon cancer: tumors of the colon. The End