Biology Journal 12/1/2014 1. What kind of reaction is shown? 2. Write out the reaction as words: Sucrose + _______ → ________ + _______ 3. When might this reaction be happing in your life? + H2 O → + Biology Journal 12/1/2014 1. 2. 3. What kind of reaction is shown? Catabolic hydrolysis Write out the reaction as words: see below When might this reaction be happing in your life? This happens whenever you eat sucrose (sugar)! + sucrose H2 O → + water → + fructose + glucose We will now learn how this is used by the digestive system! Biology Journal 12/3/2014 Dialysis tubing made from cellulose has pores in it that allow water and small molecules and ions to pass through freely, but not large molecules. • Will the bag gain or lose mass? Why? • How do these properties mimic the wall of the small intestine? • What types of membrane transport can be modelled using dialysis tubing and what parts can’t? Bag made of dialysis tubing (semi-permeable) • 10 mL of 1% starch solution • 1 mL of 1% amylase solution Water Biology Journal 11/25/014 6.1 Homework Quiz! 1. Where are villi found in the digestive tract? (a) Mouth (b) Stomach (c) Large intestine (d) Small intestine 2. Which organ makes most of the digestive enzymes? (a) Gall bladder (b) Salivary glands (c) Pancreas (d) Stomach 3. What is peristalsis? 4. What type of transport method could be used to absorb amino acids from the large intestine? Why? Biology Journal 12/2/014 D.1 Homework Quiz! 1. Ascorbic acid is … (a) Vitamin C (b) Vitamin D (c) a mineral (d) an amino acid 2. True or false: It is essential for humans to consume fatty acids. 3. List any of the following that are considered essential minerals Iron, Iodine, Phosphorous, Aluminum, Chlorine, Nickel 4. What is meant by an “essential” nutrient? What would a “non-essential” nutrient be? Biology Journal 11/26/014 Do you think you could live without your pancreas? What would it be like? Topic 6: Human physiology (20 hours) 6.1 Digestion and absorption: The structure of the wall of the small intestine allows it to move, digest and absorb food. Nature of science: Use models as representations of the real world—dialysis tubing to model absorption in the intestine. Understandings: The contraction of circular and longitudinal muscle of the small intestine mixes the food with enzymes and moves it along the gut. The pancreas secretes enzymes (amylase, lipase and an endopeptidase) into the lumen of the small intestine. Enzymes digest most macromolecules in food into monomers in the small intestine (starch, glycogen, lipids and nucleic acids are digested into monomers and that cellulose remains undigested). Some hydrolytic enzymes have economic importance, for example amylase in production of sugars from starch and in the brewing of beer. Villi increase the surface area of epithelium over which absorption is carried out. Villi absorb monomers formed by digestion as well as mineral ions and vitamins. Tissue layers should include longitudinal and circular muscles, mucosa and epithelium. Different methods of membrane transport are required to absorb different nutrients. Applications and skills: Application: Processes occurring in the small intestine that result in the digestion of starch and transport of the products of digestion to the liver. Application: Use of dialysis tubing to model absorption of digested food in the intestine. Skill: Production of an annotated diagram of the digestive system. Skill: Identification of tissue layers in transverse sections of the small intestine viewed with a microscope or in a micrograph. D.1 Human nutrition: A balanced diet is essential to human health. Nature of science: Falsification of theories with one theory being superseded by another—scurvy was thought to be specific to humans, because attempts to induce the symptoms in laboratory rats and mice were entirely unsuccessful. Understandings: Essential nutrients cannot be synthesized by the body, therefore they have to be included in the diet. Dietary minerals are essential chemical elements. Lack of essential amino acids affects the production of proteins. Malnutrition may be caused by a deficiency, imbalance or excess of nutrients in the diet. Appetite is controlled by a centre in the hypothalamus. Overweight individuals are more likely to suffer hypertension and type II diabetes. Starvation can lead to breakdown of body tissue. Applications and skills: Application: Production of ascorbic acid by some mammals, but not others that need a dietary supply. Application: Cause and treatment of phenylketonuria (PKU). Application: Lack of Vitamin D or calcium can affect bone mineralization and cause rickets or osteomalacia. Application: Breakdown of heart muscle due to anorexia. Application: Cholesterol in blood as an indicator of the risk of coronary heart disease. Skill: Determination of the energy content of food by combustion. Skill: Use of databases of nutritional content of foods and software to calculate intakes of essential nutrients from a daily diet. International-mindedness: The Vitamin and Mineral Nutrition Information System (VMNIS), formerly known as the Micronutrient Deficiency Information System (MDIS), was established in 1991 following a request by the World Health Assembly to strengthen surveillance of micronutrient deficiencies at the global level. D.2 Digestion: Digestion is controlled by nervous and hormonal mechanisms. Nature of science: Serendipity and scientific discoveries—the role of gastric acid in digestion was established by William Beaumont while observing the process of digestion in an open wound caused by gunshot. Understandings: •Nervous and hormonal mechanisms control the secretion of digestive juices. •The volume and content of gastric secretions are controlled by nervous and hormonal mechanisms. •Acid conditions in the stomach favour some hydrolysis reactions and help to control pathogens in ingested food. •The structure of cells of the epithelium of the villi is adapted (microvilli and mitochondria) to the absorption of food. •The rate of transit of materials through the large intestine is positively correlated with their fiber content. •Materials not absorbed are egested. Applications and skills: Application: The reduction of stomach acid secretion by proton pump inhibitor drugs. Application: Dehydration due to cholera toxin. Application: Helicobacter pylori infection as a cause of stomach ulcers. Skill: Identification of exocrine gland cells that secrete digestive juices and villus epithelium cells that absorb digested foods from electron micrographs. 6.1, D.1, D.2 Digestion Hydrolytic Enzymes (ones that do hydrolysis) turn food polymers into monomers. Many are made by the pancreas: 1.Amylase: Breaks down carbohydrates into sugars 2.Lipase: Breaks down polyglycerides into monoglycerides 3.Endopeptidase: Breaks down polypeptides into amino acids X-ray scan of a house cat being digested by a python. Mouth Stomach Esophagus Liver Pancreas Gall Bladder Large Intestine Small Intestine Rectum Anus 6.1.4 Draw and label a diagram of the digestive system. mouth esophagus liver stomach gall bladder pancreas small intestine large intestine rectum anus http://sciencevideos.wordpress.com Draw the Core 14 Starch digestion in the small intestine Catalysis Without a catalyst the reactions to digest starch would happen at very slow rates Illustrates many processes that we have learned about Enzyme specificity Membrane permeability Starch digestion in the small intestine Catalysis Illustrates many processes that we have learned about Membrane permeability Enzyme specificity Salivary amylase begins the digestion. Most starch digestion happens in the small intestine with enzyme secretions from the pancreas. 1,4 bonds broken by pancreatic amylase Three enzymes in villi membranes break the 1,6 bonds and the 1,4 products; dextrinase, maltase, glucosidase These small sections are now broken down into maltose and maltotriose Glucose Starch digestion in the small intestine Catalysis Illustrates many processes that we have learned about Enzyme specificity Membrane permeability Glucose is absorbed via: 1. co-transport with sodium ions 2. into the interstitial fluid via facilitated diffusion 3. through large membrane pores into capillaries. Cola drinks contain a mixture of substances with different particle sizes. This cola contains glucose, phosphoric acid, and caramel (a complex carbohydrate added to produce a brown color). • Predict which substances will diffuse out of the bag, with reasons for your prediction. • Predict whether the bag will gain or lose mass during the experiment. Cola, left to go flat before being put in a tube Bags made of dialysis tubing Water Peristalsis Contractions of circular and longitudinal muscles. Mixes food and moves it along digestive tract Peristalsis works in pretty much the same way throughout the whole digestive tract. Esophagus Small Intestine Stomach Has a pH of 2 (because of HCl) Acidic pH kills almost all bacteria & viruses Denatures proteins So, do you think that the 5 second rule is valid? Small Intestine Absorbs molecules through villi Long! (about 7 meters (23 feet) long) Small Intestine Pancreas (and liver and gallbladder) add hydrolytic enzymes What are the substrates and products of… lipase, amylase, endopeptidase What carbohydrate isn’t digested by humans? “I love chewing on my barfed-up cellulose.” Cellulose (dietary fiber) isn’t digested by humans. Villi are like a bath towel: the more surface area, the faster and more efficient the absorption. Villi are thin projections into the gut that maximize surface area for absorption of molecules. They have blood vessels in them to allow absorption of molecules into the blood. The blood delivers these molecules to be used or stored (usually stored in the liver). Large Intestine Absorbs water from food (not nutrients) Has large stores of bacteria How does diarrhea help cure you from an illness? During diarrhea, the large intestine stops absorbing water and instead attempts to purge all contents of digestive system. Identify tissue layers of longitudinal and circular muscles, mucosa, and epithelium. Identify tissue layers of longitudinal and circular muscles, mucosa, and epithelium. Identify tissue layers of longitudinal and circular muscles, mucosa, and epithelium. For next time do… D.1 Homework! Essential nutrient: A molecule that the body cannot synthesize on its own, and is necessary for survival. It must be obtained from food. Nonessential nutrient: A molecule that the body can synthesize on its own. It can, but doesn’t have to, come from food. The secretion of hydrolytic enzymes is regulated by the nervous system via hormones. These organs contain excretory glands to digest food: Mouth Stomach Pancreas Liver What specific are some of the names of the chemicals that each one secretes? Identify exocrine gland cells from electron micrographs. A sweat gland is an exocrine gland that you are familiar with!