NHM 101 1nd EditionLecture 10 Outline of Last Lecture I. Carbohydrates Outline of Current Lecture II. Carbohydrate Digestion and AbsorptionIII. Glucose in the BodyIV. Lipid Digestion and AbsorptionV. Functions of Lipids Current LectureCarbohydrate Digestion- Moutho Salivary enzyme Amylase hydrolyzes starch into smaller molecules (shorter polysaccharides or maltose)- Stomacho No new enzymes are introduced to break down CHOo Salivary amylase diminishes as stomach acid and protein digestion enzymes break it downo Fiber may promote satiety (feeling of fullness)- Small intestineo Pancreatic amylase continues breaking down polysaccharideso Final digestion takes place on outer membranes of intestinal cells Maltasebreaks maltose into 2 glucose molecules Sucrase breaks sucrose into glucose and fructose Lactasebreaks lactose into glucose and galactoseo Mostly glucose molecules remain- Large Intestineo Fibers remain and attract watero Bacteria in GI tract ferment some fibers (mainly soluble) Generates water and gas Fibers do contribute a small amount of energy for the colon (~2kcal/g)Carbohydrate AbsorptionThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.- Primarily takes place in the Small Intestineo Active Transport Glucose and galactoseo Facilitated diffusion Fructose o Fructose and galactose are metabolized by livero Glucose sent to bodys cells for energyLactose Intolerance- Only about 30% of adults have enough Lactase- Lactose Intolerance Symptomso Lactose remains undigested in intestine and attracts water Causes bloating, abdominal discomfort, and diarrheao Lactose also becomes a food for intestinal bacteria Bacteria multiply and produce irritating acid and gas Causes further abdominal discomfort and diarrhea- Lactose Intolerance Causeso Lactase declines with ageo Intestinal villi are damaged by disease, medications, prolonged diarrhea - Total elimination of milk products is usually not necessaryo Most can consume a small amount=6 grams of lactose- Managing lactose intoleranceo Experiment with milk products with a gradual increaseo Consume milk products with other foodso Consume fermented milk products Kefir and yogurto Cheese is often well toleratedo Use milk products treated with an enzyme that breaks down lactose Lactaid Glucose in the body- Primary energy source for cells- Glycogen Storageo Blood glucose rises after mealo Excess glucose molecules are combined by condensation to form glycogeno When blood glucose falls the liver cells break down glycogen by hydrolysis Single glucose molecules are released into blood stream o Muscle cells hold onto most of their glycogen to use during exerciseo Body can only sore a small amount of glycogen - What if we do not provide our body with adequate carbohydrates?o Proteins can be used to make glucose, but not easily Gluconeogenesis the making od new glucose Adequate dietary CHO is needed to prevent gluconeogenesis o Ketone bodies are formed when fat fragments combine Ketones provides fuel during starvation  When production is higher than the use, ketones accumulate in the blood Ketone bodies are acidic disturbing the acid base balance Body needs at least 50-100g of CHO per day o If too much Glucose to fat Liver will break down glucose and store as fat Blood Glucose- Steady stream of blood moves past cells to deliver glucose- Fast blood sugar between 70-99 mg/dl- Blood glucose is regulated by insulin and glucagono Both secreted by the pancreaso Insulin Blood glucose rises insulin released glucose goes into cells blood glucose returns to normalo Glucagon Blood glucose falls between meals glucagon released signals liver to breakdown glycogen stores blood glucose returns to normal Diabetes- Blood glucose remains above normal after meal due o inadequate or ineffective insulin- Type 1 Diabeteso Pancreas does not produce any or enough insulino Typically diagnosed in childhood- Type 2 Diabeteso Cells do not respond to insulino Typically occurs due to obesity- Hypoglycemiao Rare in healthy peopleo Symptoms: weakness, rapid heartbeat, sweating, anxiety, hungero Replace refined CHO with fiber-rich CHO and eat small, frequent meals Glycemic Response- Glycemic responseextend to which food raises blood glucose and elicits an insulin responseo Slow absorption or responseo Fast absorption or response (i.e. a “crash”)- Glycemic index-a method to classify foods according to their potential to raise blood glucoseo Compare 100g of food to 100g of a reference food (typically glucose or white bread)o Low: legumes, milk productso Moderate: whole grains, fruitso High: processed foods, bread, carrotsLipid Digestion- Challenge is to keep the lipids mixed vs. separationo Lipids hydrophobic o Digestive enzymes are hydrophilic- Moutho Some hard fats melt- Stomacho Muscles contract to propel contents toward pyloric sphincter o Lipid particles broken down by gastric lipase - Small Intestineo When fat enters, Cholecystokinin (CCK) is released which signals release of bile from the gallbladder - Bile acts as an emulsifier so the enzymes can act on the fat - Most fat digestion occurs in the small intestineo Pancreatic lipase and intestinal lipaseLipid Absorption- Glycerol and short- and medium- chain fatty acids absorbed directly into bloodstream- Monoglycerides and long-chain fatty acids form micelles(spherical complex)o Transported by proteins called chylomicrons - Lipid transport is made possible by a group of vehicles know as lipoproteinso Chylomicrons Largest of the lipoproteins Least dense Get smaller as triglycerides are removed from the cellso Very-Low-Density Lipoproteins (VLDL) Composed primarily of triglycerides Transport lipids to tissues Get smaller and more dense as triglycerides are removed and VLDL becomes LDLo Low-Density Lipoproteins (LDL) Composed primarily of cholesterol with few triglycerides Transport lipids to tissueso High-Density Lipoproteins (HDL) Composed primarily of protein Transport cholesterol from the cells to the livero Health Implications High LDL is associated with a higher risk of heart disease and known as “bad” cholesterol High HDL appears to have a protective effect Functions of Lipids- Part of every cell membrane-