Kaylee Hogg Exam 2 Study Guide 1 HUNGER AND APPETITE a Hunger is a physiological drive for food that occurs when the body senses that we need to eat b Appetite is a psychological desire to consume specific foods c Hypothalamus tells us when were hungry and when to seek food INTESTINAL TRACT DIGESTION ABSORPTION AND ELIMINATION OF FOOD 2 a Digestion is the process by which foods are broken down into their component molecules either mechanically or chemically i Digestion begins in the mouth The cephalic stage is the earliest phase of digestion in which the brain thinks about and prepares the digestive organs for the consumption of food ii We tastes food due to saliva which is secreted from the salivary glands 1 Taste occurs when chemicals dissolved in saliva bind with chemoreceptors called taste receptors located on taste buds iii Food that has been chewed is referred to as bolus which is swallowed and propelled to the stomach through the esophagus 1 The rhythmic waves of squeezing and pushing food down the esophagus are known as peristalsis b Absorption is the physiological process by which molecules of food are taken from c the gastrointestinal tract into the circulation Elimination is the process by which the undigested portions of food and waste products are removed from the body d GI tract is a long muscular tube consisting of several organs the mouth esophagus stomach small intestine and large intestine e enzymes and hormones of digestion i Enzymes guide digestion through hydrolysis by adding water ii Enzymes are small chemicals usually proteins that act on other chemicals to speed up bodily processes but are not changed during those processes 1 Mouth produces Salivary amylase which digests carbs 2 Stomach produces Pepsin which digests proteins and Gastric lipase which digests lipids 3 Pancreas produces Proteases which works in the small intestine to digest protein Elastase which digests fibrous proteins Pancreatic lipase which digests lipids Cholesterol esterase which digests cholesterol and Pancreatic amylase which digests carbs 4 Small intestine produces Carboxypeptidase aminopeptidase dipeptidase lipase sucrase maltase and lactase iii Hormones are chemical messengers that are secreted into the bloodstream by endocrine glands of the body 1 Insulin and Glucagon are two hormones produced in the pancreas 2 Gastrin is secreted by the stomach lining cells called G cells Gastric glands are lined with parietal and chief cells Kaylee Hogg 3 Parietal cells secret Hydrochloric Acid HCl Intrinsic factor Pepsinogen and Gastric lipase 4 Hormones involved in digestion are Gastrin Secretin Cholecystokinin CCK and Gastric Inhibitory Peptide GIP f accessory organs that facilitate digestion i Small intestine absorption take place ii Large intestine 1 The longest portion of the GI tract where most of the digestion and iii Gallbladder iv Pancreas 1 Final organ of the GI tract consisting of the cecum colon rectum and anal canal Most water is absorbed here and feces are formed 2 Also referred to as the colon 1 A pear shaped organ beneath the liver that stores bile and secrets it into the small intestine 1 Gland located behind the stomach that secretes digestive enzymes 2 Manufactures Insulin and Glucagon Responsible for manufacturing hormones that are important in metabolism 3 Pancreas secretes bicarbonate into the duodenum Pancreatic bicarbonate neutralizes acidic chyme Allows enzymes to make sure that the lining of the duodenum is not eroded v Liver 1 Largest accessory organ of GI tract and one of the most important organs of the body Production of bile occurs here and the processing of nutrient rich blood from small intestine 2 Synthesizes many chemicals the body uses while carrying out metabolic processes 3 Receives products of digestion 3 FOOD INTOLERANCE VS FOOD ALLERGY a Food intolerance is gastrointestinal discomfort that is caused by certain foods that is not a result of an immune system reaction i Lactose intolerance occurs when people do not produce sufficient of the enzyme lactase which facilitates the breakdown of the milk sugar lactose b Food allergy is an allergic reaction to food caused by a reaction of the immune system Define lactose intolerance 4 CARBOHYDRATE METABOLISM a Carbohydrates i One of three macronutrients made of carbon hydrogen and oxygen that is derived from plants Fruits Vegetables and Grains to provide energy ii Glucose is the most abundant sugar molecule it s a monosaccharide that is found in the combination with other sugars and it s the preferred source of energy for the brain and all cells iii Simple Carbs A monosaccharide or disaccharide sugar Kaylee Hogg 1 Monosaccharides are the simplest form of carbs because they consist of one sugar molecule a Glucose Fructose and Galactose are three most common monosaccharides They contain 6 carbon atoms 12 hydrogen atoms and 6 oxygen atoms 2 Disaccharides are carbs that consist of two molecules of sugar joined together a Lactose Maltose and Sucrose are most common disaccharides b Maltose is broken down into glucose by the enzyme c maltase Sucrose is broken down into glucose and fructose by the enzyme sucrase d Lactose is broken down into glucose and galactose by the enzyme lactase iv Complex Carbs A nutrient compound consisting of long chains of glucose molecules like starch glycogen and fiber 1 Oligosaccharides are complex carbs that contain 3 10 monosaccharides a Two most common are raffinose and stachyose 2 Polysaccharides are complex carbs consisting of long chains of glucose a Starch is the storage form of glucose as polysaccharides in plants b Glycogen is the storage form of glucose as a polysaccharide in animals b hormones regulating blood glucose Hormones regulating Blood Glucose levels Figure 4 8 page 129 i Insulin hormone secreted by the beta cells of the pancreas in response to increased blood levels of glucose that facilitate uptake of glucose by body cells ii Glucagon hormone secreted by the alpha cells of the pancreas in response to decreased blood levels of glucose Stimulates the liver to convert stored glycogen into glucose which is released in the blood stream and transported to cells for energy c glycemic index and glycemic load Glycemic Index i A rating of the potential of foods to raise blood glucose and insulin levels ii Foods with high glycemic index cause a sudden surge in blood glucose which triggers a large increase in insulin which can be followed by a drop in blood glucose iii Foods with
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