NTR Midterm review, Chapters 1-7 and quizzes with verified solutions., Exams of Nutrition and Aging

Download NTR Midterm review, Chapters 1-7 and quizzes with verified solutions. and more Exams Nutrition and Aging in PDF only on Docsity! NTR Midterm review, Chapters 1-7 and quizzes with verified solutions. Nutrition is the branch of science that ONLY focuses on identifying the nutrients that are in foods. - ANS false Which of the following individuals have the training, expertise, and education necessary to provide accurate nutrition information and recommendations? (Select 2) - ANS correct: - PhD-level (Degreed) Nutritionist - Registered Dietitian Incorrect: - Certified Nutritionist - Personal Trainer - Nutritional Consultant What is an essential nutrient? - ANS correct: - A nutrient that is needed but must be obtained from food (because the body cannot make it). Incorrect: - A nutrient that you can only get from supplements. - A nutrient that is helpful but not needed. - A nutrient that is needed but can be made by the body. Which of the following substances are inorganic (select 2)? - ANS correct: - Minerals - Water Incorrect: - Vitamin A - Lipids Which of the following substances does not provide energy? - ANS correct: -minerals Incorrect: - Proteins - Alcohol - Carbohydrates What essential nutrient is involved in nearly all body processes (like metabolic reactions, fluid balance, nerve impulses, muscle contractions, and nutrient transport)? - ANS correct: - Water Incorrect: - Oxygen - Vitamin D - Carbon A half-cup of vanilla ice cream contains 29 grams of carbohydrate, 2 grams of protein and 20 grams of fat. How many total kilocalories does this ice cream contain? - ANS answer: - 304 kcals (calories) Steps: P a g e 1 | 40 A veggie burger patty is 136 kilocalories and contains 15 grams of carbohydrate, 10 grams of protein and 4 grams of fat. What percentage of the energy in the burger comes from carbohydrate? - ANS answer: - 44% Steps: The AMDR for protein is between - ANS correct: - 10-35% of total energy intake Notes: The AMDR for carbohydrate is between - ANS correct: - 45-65% of total energy intake Notes: A person is 'doing keno' and consumes 20 g of carbohydrates/day in a 2000 kilocalorie diet. How does this amount fit with the AMDR? - ANS correct: - It's below the AMDR Why: The pack of cookies that your roommate purchased has the following nutrients facts panel: - Serving Size: 32g (3 cookies), - Servings per Container 11 - Calories 160 - Total Fat 8g, Saturated fat 2.5g, Cholesterol 0mg, and Trans Fat 0g - Sodium 105mg - Total Carbohydrate 21g - Added Sugars 15g - Dietary Fiber 1g - Protein 2g If your roommate ate 9 cookies, how many kilocalories would she consume? - ANS answer: 480 kcals Steps: Nutrition recommendations are often developed from the findings of a single study. - ANS false An experimental study examines the effects of an intervention on a specific outcome. - ANS true The maximum amount of a nutrient that appears safe for most healthy people but beyond that might be 'toxic' or might increase the risk of adverse health effects is the ______________ - ANS UL (Upper limit) The average daily amount of a nutrient that appears sufficient to maintain function when the RDA can't be set (due to lack of sufficient evidence) is the _________________ - ANS AI The average daily amount of a nutrient 'required' to maintain health in 50% of healthy adults is the ___________ - ANS EAR Malnutrition applies to which of the following: (select 2) - ANS - under nutrition - Over nutrition P a g e 2 | 40 What is the common name of the disaccharide molecule that contains glucose + GA lactose? - ANS milk sugar Which statement is true about polysaccharides? - ANS true: - Chemical digestion of starch begins in the mouth False: - Starch is indigestible. - Fiber is the storage form of glucose in the body. - Glycogen is the storage form of glucose in plants. What are the recommended dietary strategies for individuals with lactose intolerance? (Select 2) - ANS - Gradually increase milk intake & consume it with other foods - Consume yogurt or lactose-free milk Brain - ANS organ is the primary user of glucose in the body? Insulin and glucagon - ANS When blood glucose rises, the pancreas secretes ________ to promote glucose update into the cells. However, when blood glucose falls, the pancreas secretes ________ to breakdown glycogen into glucose for use. When we consume inadequate amounts of carbohydrates (<50 g/d), how does the body respond? (Select 2) - ANS correct: - Fat gets broken down to form ketone bodies (for fuel) - Protein gets broken down to form glucose Wrong: - Fiber gets broken down to form glucose - We immediately go into cardiac arrest and die The primary reason why a diet high in added sugars is 'harmful' is because the foods/beverages containing the added sugar are nutrient poor but energy dense and displace the consumption of nutrient dense foods. - ANS true The recommended fiber intake in adults is - ANS 25 g/day for women 38 g/day for men Prediabetes - ANS If you have a fasting blood glucose of 115 mg/ld., what range are you in 50% - ANS What percent of the grains that you consume should be whole grains? False - ANS Fiber supplements are just as effective as consuming fiber-rich foods. Which energy-yielding nutrient supplies about 60% of the body's energy needs during rest? - ANS fat What are the 3 types of Lipids? (Select all that apply) - ANS Triglycerides Phospholipids Sterols Not: Monosaccharides Polypeptides Triglycerides are made up of: (Select all that apply) - ANS - 3 fatty acids - Glycerol Not 1 fatty acid/amino acids P a g e 5 | 40 Which type of fatty acids have double bonds (and thus less hydrogen’s on their chemical backbone) which contribute to their protective nature in reducing the risk of chronic disease? - ANS Unsaturated Fatty Acids Which of the following blood lipids are associated with an increased risk of chronic disease? (Select 2) - ANS - LDL cholesterol - Triglycerides The health effects of dietary fats are only dependent on the quantity that is consumed. - ANS false Which of the following statements are true about polyunsaturated fats? (Select 3) - ANS - spoils readily - Liquid at room temperature - lowers LDL blood cholesterol Which of the following statements are true about saturated fats? (Select 3) - ANS - more resistant to oxidation - contributes to elevated LDL blood cholesterol - Solid at room temperature Which of the following is NOT true of high density lipoprotein (HDL)? - ANS not true: - deliver triglycerides to cells True: - synthesized in the liver - Exhibit anti-inflammatory properties - removes cholesterol from cells Which of the following is NOT true of very low density lipoprotein (VLDL)? - ANS not true: - removes cholesterol from cells True: - Acts as "water taxi" for triglycerides, delivering lipids to body cells - synthesized in the liver - Eventually becomes LDL What substance is released from the gall bladder and binds to the large fat globules in the lumen of the small intestine, breaking them into smaller "emulsified fat" droplets? - ANS bile All cholesterol, including dietary and internally-made, is harmful to the body and is not a vital compound. - ANS false Which fatty acids are anti-inflammatory, improve heart health, and are involved with structure and function of cells in the eyes and brain? - ANS polyunsaturated, omega-3 fatty acids Which sources are rich in omega 3 fatty acids? (Select 2) - ANS - flaxseed oil - Salmon The Dietary Guidelines for Americans recommends consuming__________ of daily intake from saturated fats? - ANS <10% Proteins - ANS what compounds are considered the building blocks of the body and are primarily responsible for growth and maintenance? Essential amino acids are those which: - ANS the body needs but cannot synthesize Muscle - ANS During times of starvation, energy restriction, or insufficient carbohydrate intake, which of the following body protein sources will be broken down first? P a g e 6 | 40 Protein is made in the body using encoded information within the DNA of our cells. - ANS true Which element is unique to protein-containing molecules? - ANS nitrogen Which type of enzymes assist with catabolizing proteins into amino acids? - ANS proteases Where are amino acids stored in the body (to use when needed)? - ANS they are not stored anywhere 0.6 g protein/kg body weight/day is needed to prevent deficiencies in adults but 0.8 g protein/kg body weight/day is needed for health benefits in adults. - ANS answer 1: 0.8 g protein/kg body weight/day Answer 2: 1.2-1.6 g protein/kg body weight/day Select two foods that can be combined to make a complete protein. - ANS beans and rice Protein quality is based on digestibility and amino acid composition. Thus, based on these factors which protein sources generally have the highest protein quality? - ANS animal sources What is the most common sign of protein deficiency? - ANS stunting Nutrition is the branch of science examining - ANS - The nutrients in foods and their actions within the body - Human behaviors related to food & eating & drinking Nutrients - ANS - a substance that provides nourishment essential for growth and the maintenance of life - Chemical substances in foods - provide energy, structural materials, regulating agents - support growth, tissue maintenance and repair, and reduce disease risks Foods - ANS products derived from plants or animals that can be taken into the body to yield energy and nutrients for the maintenance of life and the growth and repair of tissues Nutrition experts - ANS - Registered dietitian (RD) - Degreed nutritionists Not nutrition experts - ANS - Non-nutrition degree, un-trained 'titled' individuals - (Most) physicians and healthcare professionals What's the problem? - ANS - Dietary advice is everywhere & is ever-changing (even from experts) - Difficulty in understanding current & accurate information Which food contains the greatest carbohydrate content by weight? - ANS Orange Food choices - ANS - diet - Personal preference - Habit - Ethnic heritage and regional cuisine - Social interactions - Marketing - Availability, convenience and economy - Positive and negative associations P a g e 7 | 40 Experimental studies - ANS Studies in which a change in diet, nutrient or eating behavior is prescribed - Investigators do interfere and try to influence health outcomes - Used to identify a cause and effect between a (nutrition) factor and health (or disease) - Human clinical trials: large (1,000s) or small (n=10) - Must have a control group to compare to Types of data (examples): - Dose response - Multiple treatments - Multiple groups Dietary Reference Intakes (DRIs) - ANS - Standards that define the amount of energy, nutrients and water intake to best support health - Developed by the Institute of Medicine (IOM) - Recommendations apply to healthy people - Continually updated DRI's 4 main components - ANS 1. Estimated average requirements (EAR) 2. Recommendation dietary allowance (RDA) 3. Adequate intake (AI) 4. Tolerable upper limits (UL) Estimated average requirements (EAR) - ANS Average daily amount of a nutrient required to maintain health in 50% of healthy adults - Differs by group: age, sex If someone consumes less than requirement: - Nutrient stores decline - Can lead to health problems Recommendation dietary allowance (RDA) - ANS Average daily amount of a nutrient recommended as adequate to meet the nutrient needs of most healthy people - EAR is needed to set the RDA - The RDA goal is for most people - Set high to make sure 98% healthy people will not be deficient - Differs by group: age, sex Adequate Intakes (AI) - ANS Average daily amount of a nutrient that appears sufficient to maintain health when the RDA can't be set (due to lack of sufficient evidence) - Relies on scientific judgments, not evidence - AI is set instead of RDA - Less valid, less rigorous Tolerable Upper Limit (UL) - ANS Maximum daily amount of a nutrient that appears safe for most healthy people - Beyond the UL is likely to be toxic or cause adverse health effects - UL helps protect against overconsumption and can result from dietary supplement use Estimated Energy Requirement (EER) - ANS Average energy intake (calories = kcal) to maintain energy balance - Energy balance: kcals consumed = kcals used (energy in = energy out) - Represents someone with: Health body weight and who is physically active - No UL for calories: any excess = weight gain Acceptable Macronutrient Distribution Ranges (AMDR) - ANS Adequate intake of energy and nutrients to: - Support health - Reduce risk of chronic diseases Ranges: - 45-65% calories from carbohydrate - 20-35% calories from fat - 10-35% calories from protein P a g e 10 | 40 Using Nutrient Recommendations - ANS - Estimates apply to healthy people - Recommendations - not minimum nor optimal levels - Goals are intended to be met through diet - Apply to average daily intakes over time - Each DRI component serves a unique purpose - Specific to the United States Dietary Guidelines for Americans (DGAs) - ANS Food (and beverage) based recommendations, through scientific evidence for healthy individuals, to help: - Achieve good health - Reduce risk of diet-related chronic diseases - Meet nutrient needs Used in the following programs - School nutrition programs (breakfast & lunch) - Federal foodservice (hospitals, correction facilities, military) - Nutrition research - DGAs are NOT nutrient requirements (which is what the DRIs are) - DGAs began in 1980, published every 5 years - Developed from an evidenced-based document - Provides the current status of American Diet Quality 2020-2025 DGA Key Recommendations - ANS - Follow a healthy dietary pattern at every life stage - Customize and enjoy nutrient-dense food and beverage choices to reflect personal preferences, cultural traditions and budgetary considerations - Focus on meeting food group needs with nutrient-dense foods & beverages, and stay within calorie limits - Limit foods and beverages higher in added sugar, saturated fat and sodium and limit alcoholic beverages Specific limits - ANS - Added sugars: <10% beginning age 2+ - Saturated fat: <10% of calories, ages 2+ - Sodium: <2,300 mg/d, ages 14+ Alcoholic beverages: - Drinking less is better than drinking more - Can choose not to drink or limit intake to less than 2 drinks/day Key Dietary Principles - ANS - Meet nutritional needs primarily from foods and beverages - Choose a variety of options from each food group - Pay attention to portion size 85% - ANS of calories are needed per day to meet food group recommendations healthfully, in nutrient-dense forms (1,700 kcal food groups) 15% - ANS of remaining calories are available for other uses (including added sugars and saturated fat, 300 kcal discretionary) Under nutrition (inadequacy/deficiency) - ANS - Inadequate energy (calories): thin, muscle loss, reduced immune function, increased disease, etc. - Inadequate nutrient(s): skin rash, hair loss, night blindness, bleeding gums, muscle spasms, etc. Over nutrition (surplus/excess) - ANS - Surplus energy (calories): unhealthy weight gain, obesity, type 2 diabetes, cardiovascular disease, etc. - Surplus nutrient(s): hot flashes, yellowing skin, rapid heart rate, low blood pressure, etc. Individual level nutrition assessment - ANS Helpful for detecting malnutrition and correcting problems - Demographics: age, sex, ethnicity, socio-economic status (SES), etc. P a g e 11 | 40 - Medical history: health status, drug/alcohol use, family history of disease - Diet record: collection of intake over several (3-7) days to assess foods, beverages, supplements and the quantities consumed - Anthropometric measurements: height and weight -> BMI - Physical exam: visual inspection, interview to identify symptoms - Laboratory tests: blood or urine analysis to ID early signs before symptoms appear Population level nutrition assessment - ANS National nutrition surveys (population data) - National health and nutrition examination survey (NHANES) - USDAs Continuing Survey of Food Intakes by Individuals (CSFII) What We Eat in America (combination of both surveys above) - Data used for: public policy; research; product development; establishing national health goals National health goals - Healthy people programs: increase the quality the quality and years of healthy life; eliminate health disparities - Healthy eating index (HEI) score: whether Americans are meeting guidelines Dietary principles - ANS 1. Adequacy: energy (kcals) and nutrients 2. Balanced diet: enough but not too much and different types of foods to meet recommendations 3. Energy balance: energy intake = energy expenditure 4. Nutrient density: ratio of recommended nutrients: total energy - High nutrient density = most nutrients for fewest kcals - Low nutrient density = high energy density, least nutrients for greatest kcals 5. Moderation: consume low-nutrient dense, high-energy dense foods occasionally - Ultra - processed foods (added ingredients) - High: sodium, added sugar and or saturated fats *Remember less than or equal to 15% of your diet* 6. Food-first mentality: all nutrient needs can (and should) be fulfilled with foods, not supplements for most individuals 7. Portion size: use portion size guides, choose smallest, ID portion sizes on packages, significantly increased over the past 20 years 8. Variety: increased variety within food groups as not all foods are 'created equally' 3 example patterns within the DGAs - ANS - Healthy US-style dietary pattern - Healthy vegetarian dietary pattern - Healthy Mediterranean-style dietary pattern Healthy Dietary Patterns - ANS - All patterns are 'plant-based' with the majority of calories and foods coming from plants - Vary in the amounts and types of foods included - All patterns limit the amount of added sugar, saturated fat and alcohol Diet Planning Guides - ANS - Need tools and knowledge to plan an ideal diet USDA food patterns: assign foods to five major groups - Recommended daily amounts for each food group - Notable nutrients - Serving equivalents (ounces, cups, etc.) - Nutrient density USDA food patterns - ANS - Notable nutrients - Discretionary calorie allowance (85-15 rule) - Serving equivalents - Mixture of foods Unique diets: vegetarians and ethnic food choices My Plate (website) - ANS - Combines USDA food patterns and dietary guidelines - Educational tools on website - Allows for personal planning: height, weight, age, sex, activity level, different phases in lifecycle - Addresses pyramid shortcomings: visual reminder for every meal P a g e 12 | 40 Five organs - ANS Salivary glands, stomach, pancreas, liver (via gallbladder) and small intestine Secretions - ANS - Enzymes: protein facilitator of chemical reactions*Breaking down, making, or changing molecules* - Catalyst: enzymes remain unchanged - Hydrolysis: addition of water to break molecule into small pieces - Organ of origin + compound + -as = enzyme *Gastric lipase = stomach enzyme that digests lipids* Saliva - ANS - Moisten food for easy passage - Protective role: teeth, mouth esophagus, stomach - Enzymes initiate carbohydrate digestion Gastric juice - ANS - Protein digestion (hydrochloric acid)*Heartburn* - Mucus protects stomach lining - PH below 2 (more acidic than lemon juice) Pancreatic juice - ANS - Released via ducts into duodenum (small intestine) - Enzymes act on all 3 energy nutrients: Carbohydrates, fats and proteins - Sodium bicarbonate: Basic/alkaline, Neutralizes acid in chime from stomach - Bile: produced liver; Concentrated, stored, and released: gallbladder; squirts into duodenum; Emulsifier (NOT an enzyme)*Disperses fat in watery solutions; Gives digestive enzymes access to fat molecules* The final stage - ANS - Carbohydrate, fat and protein = digested - Vitamins and minerals = absorbed - Undigested residues enter colon (large intestine): Fluids, dissolved salts, fiber - Colon *Intestinal bacteria ferment some fiber: produces water, gas and fat = energy for colon*some fiber passes through unchanged*Water and dissolved salts: recycled for use in other parts of body* - Rectum and anus: eliminate stool Small intestine (absorption) - ANS - Majority of absorption - Ten feet long (surface area = 1 ½ bowling lanes) - Absorption techniques (a)Simple diffusion (b)Facilitated diffusion (c)Active transport Villi (absorption) - ANS - Fingerlike projections on intestinal folds - thousands per fold! - Imagine: like a sea anemone - Select and regulate nutrients absorbed based on needs of body Microvilli (absorption) - ANS Enzymes and "pumps" act on different nutrients Crypts (absorption) - ANS Glands secrete intestinal juices = digestion Goblet cells (absorption) - ANS Secrete mucus = protection Simple diffusion - ANS some nutrients (such as water and small lipids) are absorbed by simple diffusion. They cross into intestinal cells freely Facilitated diffusion - ANS some nutrients (such as the water-soluble vitamins) are absorbed by facilitated diffusion. They need a specific carrier to transport them from one side of the cell membrane to the other. (Alternatively, facilitated diffusion may occur when the carrier changes the cell membrane in such a way that the nutrients can pass through) P a g e 15 | 40 Active transport - ANS Some nutrients (such as glucose and amino acids) must be absorbed actively. These nutrients move against a concentration gradient (from areas of low concentration to areas of high concentration), which requires energy Preparing nutrients for transport - ANS Nutrients are absorbed (crossed into villus cell), enters one of two transport pathways: - Bloodstream - Lymphatic system Bloodstream - ANS - Water-soluble nutrients and smaller products of fat digestion - Guided directly to liver Lymphatic system - ANS - Larger fats and fat-soluble vitamins (insoluble in water) - Intestinal cells assemble products of fat digestion into larger molecules, cluster with proteins to become: Chylomicrons (fat transporters) - umber for fat molecules - Bypass liver at first Vascular System - ANS CLOSED SYSTEM OF VESSELS - Continuous blood flow - Heart = pump BLOOD - Delivers oxygen and nutrients to body tissues - Removes carbon dioxide and wastes from body tissues - Normal blood flow: Heart -> arteries -> capillaries -> veins -> heart - Special route for digestive system blood: Heart -> artery -> capillaries (in intestines) -> hepatic portal vein -> capillaries (in liver) -> hepatic vein -> heart - Liver = hero! *Direct to receive nutrients from GI tract (before heart)*Prepares absorbed nutrients (carbohydrates, fats, proteins, etc.) for use in the body*Detoxifies harmful substances; prepares waste for excretion* Lymphatic system - ANS One-way route, flows toward heart - No pump - Circulation between cells in response to body movement Entry into bloodstream - Collects in thoracic duct (behind heart) -> subclavian vein -> bloodstream Nutrients in lymphatic vessels - Large fats and fat-soluble vitamins - Bypass liver at first Who is the superhero of the digestive system? - ANS Liver Gastrointestinal micro biota (gut flora) - ANS 100 trillion microbes: bacteria, viruses, fungi, protozoa, etc. Bacteria alone: 400 species and subspecies Factors influencing micro biota: - Diet: short and long term choices - Plant-based diet: high fiber = energy source for beneficial bacteria - Obese people: less diverse gut microbial life - Prebiotics: encourage bacterial growth and activity - Probiotics: live microbes that change GI conditions in positive way Potential benefits of GI microbes: - ANS alleviate/prevent: constipation, diarrhea, inflammatory bowel syndrome, inflammation, ulcers, allergies, lactose intolerance, colic (infants) enhance immune function; protect against colon cancer; lower blood cholesterol; lower blood pressure (Endocrine and nervous systems) Homeostatic regulation - ANS Body should maintaining "business as usual" P a g e 16 | 40 - Hormones (endocrine) and nerve pathways (nervous system) coordinate all digestive and absorptive processes - Stimulation and inhibition of digestive secretions as food travels through GI tract (Endocrine and nervous systems) Feedback mechanisms - ANS GI hormones regulate digestion and absorption with negative feedback loops Gastrin - ANS secreted by cells in stomach wall Secretin - ANS secreted by cells in duodenum wall Cholecystokinin (CCK) - ANS secreted by cells in intestinal wall The digestive system at its best - ANS Sensitive and responsive to environment - GI tract cells provide immunity against intestinal diseases - Secretions defend against foreign invaders Health of digestive system - Healthy supply of blood - Lifestyle factors: sleep, physical activity, stress - Types of foods eaten: Balance, moderation, adequacy and variety Choking - ANS Food slips into trachea - Cuts off breathing International sign for choking - Heimlich maneuver Foods commonly associated with choking - Meat (chunks), hot dogs, nuts, grapes, carrots, marshmallows, hard candy, gum, popcorn, peanut butter Prevention of choking - Small bites, chew thoroughly, don't talk/laugh/breathe heavily while eating Vomiting - ANS Adaptive mechanism of the body - Get rid of irritants Medical treatment - Dehydration and loss of salt - Repeated vomiting = damage to esophagus, salivary glands, teeth, gums Diarrhea - ANS Intestinal contents move too quickly, Dehydration and loss of salt, Symptom of medical conditions - Irritable bowel syndrome (IBS): identify and avoid irritating foods - Colitis: avoid greedy foods, milk products and high-fiber foods - Celiac disease: gluten-free diet Constipation - ANS - Symptom, not a disease - Symptoms of constipation: straining, hard stool, infrequent bowel movements, discomfort, headaches, backaches, passing gas - Causes: lifestyle "too busy," side effect of medications - Prevention: Fiber (25g - 28g), water and physical activity Belching - ANS - Swallowed air - Prevention: eat slowly, chew thoroughly, and relax Intestinal gas - ANS Consumption of certain foods - Individually determined - Common offenders: foods rich in carbohydrates - Sugars, starches, fibers Gastro esophageal reflux - ANS - Heartburn - Indigestion - Repeated acid splashes = damage to esophagus P a g e 17 | 40 - Polysaccharides (starch) (small amount) - amylase -> smaller polysaccharides CHO digestion - stomach - ANS None - Stomach acid (HCI) neutralizes salivary amylase - No enzymes here for CHO digestion CHO digestion - small intestine - ANS - Most digestion occurs here! - Pancreatic amylase from pancreas) - Other enzymes *Polysaccharides (starch) (remainder) - amylase -> smaller polysaccharides, disaccharides, monosaccharide’s* *Disaccharides - 'aces' -> Monosaccharide’s* CHO digestion - large intestine - ANS - None - Only 1 thing left: fiber - Fermentation: *Bacteria -> enzymes -> fiber* *Non-digestible polysaccharides (fiber) - bacterial enzymes -> Water (soften stools), Gas, Short-chain fatty acids -> Energy (colon) CHO digestion - resistant starches - ANS - CHO-rich foods that are poorly digested - Pass through the small intestine - In the large intestine, they act like a fiber - May prevent some chronic diseases: diabetes, colon cancer, obesity CHO digestion - FODMAP - ANS Fermentable Oligosaccharides, Disaccharides, Monosaccharide’s And Polios - CHO-rich foods that are poorly digested - Pass through the small intestine - Fermented by bacteria in colon: Gas, diarrhea/constipation Glucose and GA lactose transport - ANS active transport and requires energy (ATP) -> blood -> body Fructose transport - ANS facilitated transport and no energy is needed -> blood -> liver Lactose intolerance - ANS Defined: reduction in lactose digestion Symptoms of intolerance - Increase in water and feeds GI bacteria (large intestine) - Bloating, abdominal discomfort, gas, diarrhea Cause: reduction in lactase - Age - Genetics - Diseases/Medications - Dietary habits Lactose Intolerance - dietary strategies - ANS - Manage dairy consumption rather than eliminate - Most can tolerate 6 g lactose (½ cup milk) - Gradually increase milk intake (with other foods, etc.) - Consume yogurt or lactose free milk - Tolerance varies - individualize diet Daily recommendation (added sugar) - ANS less than 25g Digestion -> absorption -> - ANS metabolism: biochemical processes that provide energy to living cells (Blood -> cells -> energy) Carbohydrate (CHO) metabolism pt. 1 - ANS - Glucose = central focus of carbohydrate metabolism - Glycogen = stored form of glucose - Condensation (linking) reactions turn glucose -> glycogen (when blood glucose rises) P a g e 20 | 40 - Hydrolysis (breaking) reactions turn glycogen -> glucose (when blood glucose falls) - Liver = stores ¼ of total glycogen *Released into blood as needed*enough in storage for about one day* - Muscles store ¾ of total glycogen *Hoards glycogen for use during exercise* - Brain stores small amount of glycogen (for emergencies) Carbohydrate (CHO) metabolism pt. 2 - ANS Glucose = energy for most cells - Especially brain, nerve cells and developing red blood cells - Cells break down glucose into smaller compounds (energy (ATP) released during process) Inadequate dietary carbohydrates (glucose)? - ANS - Cells convert amino acids (from protein) to glucose: Gluconeogenesis - Dietary carbohydrates play protein sparing role Fat metabolism shifts: Fat fragments combine with one another -> ketone bodies (acidic) - Provide alternative fuel during starvation - Ketone body production exceeds use = accumulate in blood -> ketosis - Ketosis disrupts body's acid-base balance - Body needs 50-100g of carbohydrates per day to spare body proteins and prevent ketosis Abundant dietary carbohydrates (glucose)? - ANS - Fat metabolism shifts - Body burns more glucose instead of fat (fat is conserved) - Body converts excess glucose into fat for storage (fat is created) - Fat cells can store almost unlimited stores of fat Primary user of glucose = brain - ANS - Uses 60% total glucose (120 grams/day; 420kcal) - When available glucose drops to half that amount, problems occur - Powers the transmission of nerve impulses and synthesizes neurotransmitters: thinking, memory, learning, initiation of movement, etc. - Can use ketones (when needed) Secondary users = muscles, liver, adipose (fat cells), kidneys, red blood cells - ANS All of these (except red blood cells) have additional energy sources to use Steady supply of glucose delivered to cells via blood stream: - ANS - Glucose brought from intestines (from food) - Glucose brought from liver (from glycogen stores or gluconeogenesis) Blood glucose: must remain in normal range for body to function (homeostasis) - ANS Regulated by hormones: - Insulin: moves glucose from blood into cells - Glucagon: brings glucose out of storage when needed - Epinephrine: signals liver cells to release glucose during stress (Fight or flight response) Deficit-state (low blood glucose) - ANS pancreas secretes glucose -> liver breaks down glycogen into glucose -> normal blood glucose Surplus-state (high blood glucose) - ANS pancreas secretes insulin -> cells take in glucose, liver stores glycogen -> normal blood glucose The constancy of blood glucose - ANS Balancing within the normal range: dependent on food and hormones - Key = balanced meals (with carbohydrates) at regular intervals Irregularities in blood glucose levels - ANS - Diabetes: high blood glucose (hyperglycemia) - Insulin is either inadequate or ineffective - Type 1 diabetes: pancreas doesn't produce insulin P a g e 21 | 40 - Type 2 diabetes: cells do not respond to insulin (related to obesity) - Hypoglycemia: low blood glucose (rare - usually result of poorly managed diabetes) Glycemic response - ANS - How quickly glucose is absorbed, how high blood glucose rises and how quickly blood glucose returns to normal levels - Low glycemic response (desired) *Slow absorption, modest rise, smooth return to normal* - High glycemic response (less desirable) *Fast absorption, surge, plunge* - Glycemic index: categorizes foods based on glycemic response elicited Glycemic index of selected foods - ANS - Pros: low glycemic index foods may improve glucose control and lower diabetes risk - Cons: hasn't been determined for many foods; people have different glycemic responses to the same food; isn't intuitive or listed on nutrition labels; is variable depending on plant variety, cooking/processing method, time of day consumed and consumed with other foods - May be unnecessary: current guidelines already suggest eating low glycemic foods Health effects of sugars - ANS - Pleasure in moderate amounts - Average US diet contains too much - Moderate intake is not detrimental to health...moderation is hard! Sugar provides glucose and energy (calories) but few nutrients - ANS Difficult to have high sugar diet + necessary proteins, fiber, vitamins and stay within calorie limit - Sugar displaces nutrients - Mom was right...eat your veggies before your dessert! Amount of "allowable" sugar depends on available discretionary calorie Honey - ANS - Natural does not equal healthy - Similar composition to table sugar (glucose + fructose) - Density: more energy per spoonful than table sugar - Contains a few vitamins and minerals Dental caries - ANS - Bacteria ferment sugars (natural and added) -> produce acid - Factors of tooth decay: > Time food spends in mouth > Sticky foods > Frequency of sugar consumption > 20-30 minutes of acid production after eating Prevention: - Reduce consumption of sugar- and starch- containing foods and beverages - Good oral hygiene Dietary guidelines of sugar - ANS - Most sugar comes from processed foods: SSB, desserts and candy - Read those labels! *New labels separate added sugar from total sugar**1 tsp. sugar = 4 grams carbohydrates = 20 calories* - DRI: no UL for sugar *AHA and WHO < 5% of daily calorie intake: 100 kcals (25g)/day: 6 tsp.* - Reduce sugar intake gradually (perceptions of sweetness change) Alternative sweeteners - ANS Artificial sweeteners: saccharin; aspartame; sucralose - Large does may have adverse effects Natural sweeteners: Stevia (Trivia); Monk fruit - Generally recognized as safe (GRAS) Nutritive sweeteners (provide calories) - Sugar alcohols (polios) *Naturally occurring in fruits and vegetables, used in processed foods* - Benefits: low glycemic response, don't contribute to dental caries - Side effects (FODMAP): bloating, gas, GI discomfort, diarrhea - Use in moderation P a g e 22 | 40 Lipids composition - ANS - carbon, hydrogen, oxygen - More carbons and hydrogen’s than oxygen’s - More energy provided per gram Calories for lipids v carbohydrates and proteins - ANS L: 9 calories/gram C&P: 4 calories/gram Fatty acids - ANS - even number of carbons - Saturated or unsaturated - Omega 3 and omega 6 fatty acids: body cannot synthesize - Organic acid - Usually even # of carbons Methyl group at one end (fatty acid) - ANS CH3 Acid group at other end (fatty acid) - ANS COOH Long-chain - ANS greater than 12 carbons Medium-chain - ANS 8-12 carbons Short-chain - ANS 6 carbons Saturated - ANS full of hydrogen’s Unsaturated - ANS - missing hydrogen’s - Double bond C Double bond C - ANS point of unsaturation Monounsaturated - ANS 1 double bond C Polyunsaturated - ANS 2 or more double bond C Polyunsaturated fatty acids identified by - ANS location of double bonded C's Omega number is the position of double bond neatest methyl end of carbon chain - ANS - 3C away from CH3 = omega 3 (linoleic acid) - 6C away from CH3 = omega 6 (linoleic acid) Monounsaturated fatty acids - ANS 9C away from CH3 = omega 9 (oleic acid) Chemical composition of fats - ANS - existence, number and location of double bonded Cs - influences characteristics of fats and oils in foods Degree of unsaturation (# of double bonded Cs)/firmness at room temperature - ANS - polyunsaturated fats (most from veggies) = liquid - Saturated fats (most from animals) = solid - Saturated fats (from plants) = solid softer... Oxidation - ANS spoilage of fats - Polyunsaturated spoil quickly (many double bonded Cs = unstable) - saturated keep longest (no double bonded Cs) Manufacturer options for protecting against oxidation - ANS - expensive storage - Addition of antioxidants - Hydrogenation Hydrogenation - ANS - hydrogen molecules added to points of unsaturation (becomes saturated) P a g e 25 | 40 - Advantages: longer shelf life (less oxidation), alters textures of fats - Disadvantages: partially hydrogenated = some double bonds change from cist -> Trans configuration Total hydrogenation - ANS rarely occurs in food processing Cist - ANS H next to double bonds on same side of carbon chain Trans - ANS H next to double bonds on opposite sides of carbon chain Body processes trans-fat like saturated fat - ANS Increase blood cholesterol and heart disease risk Phospholipids - ANS - Two fatty acids: hydrophobic: fat soluble - AND phosphate group + N-containing compound: Phosphate group: hydrophilic: water soluble - Versatile: emulsifiers in food industry - Lecithin: best known phospholipid - Part of cell membranes - Vitamin and hormone transport in/out of cells - Emulsifier: keep fat suspended in blood Sterols - ANS - Multiple-ring structure FOOD SOURCES: - Cholesterol: animal sources (meat, eggs, seafood, and poultry, dairy) - Plant sterols: structurally similar to cholesterol -> interfere with cholesterol absorption - > lower blood cholesterol - Vital body compounds made from cholesterol: bile acids, sex and adrenal hormones, vitamin D, cholesterol - 90% of body cholesterol = in cells (does not equal energy) - Cholesterol made in the body = endogenous (synthesized by liver) - Cholesterol made outside the body (foods) = exogenous - Accumulation in artery walls and plaque formation = harmful Lipid Digestion and Absorption - ANS - Ultimate goal: break ingested foods into smaller molecules for use by the body - Digestion: break ingested foods into smaller molecules (lipids->FAs, Glycerol, Mon glycerides) -> absorption: moving the smaller molecules for use in the body (FAs, Glycerol -> blood, monoglycerides) Lipid digestion in mouth - ANS - Small amount of digestion (<5%) - Lingual (tongue) lipase - Triglycerides (milk fats) - (lipase) - > monoglycerides free fatty acids glycerol’s - Lingual lipase - Infants: fatty acids in milk - Adults: less active Lipid digestion in small intestine - ANS - Most digestion occurs here (75%) 1. Fat stimulates CCK secretion (from small intestine) 2. CCK stimulates bile secretion (from the gallbladder) 3. Bile stimulates the breakdown of large fat particles Importance of bile - ANS - Not an enzyme or hormone - Made from cholesterol - Compound that acts as an emulsifier - (Bile acids: hydrophobic (water-hating) - (Amino acids: hydrophilic (water-loving) - Emulsifier: a substance that causes the mixing of two or more substances (that would normally not mix) *oil and water* -> *emulsified oil and water* Lipid digestion in the large intestine - ANS none P a g e 26 | 40 Lipid Absorption - Introduction - ANS - Small molecules (glycerol and fatty acids) are absorbed and go directly into bloodstream - Large molecules (micelles) are absorbed but get broken down and reassembled into new triglycerides - New triglycerides + cholesterol + phospholipids + proteins = chylomicrons - Chylomicrons released into lymphatics - Bypass the liver (allows other organs accessibility) - Released into the circulation later on Lipid transport - in circulation (blood stream) - ANS - Lipoproteins: transport vehicles for fats in blood - Lipoproteins: transport vehicles for lipids in blood VARY BY SIZE AND DENSITY - More triglycerides (TGs) = less dense, larger - More proteins = more dense, smaller LARGEST (most TGs) TO SMALLEST (least TGs) - Chylomicrons - Very-low-density-lipoproteins (VLDL) - Low-density-lipoproteins (LDL) - High-density-lipoproteins (HDL) Chylomicrons - ANS - Transports triglycerides to most cells - As they dump the triglycerides, they get smaller - Liver removes remaining parts - synthesized in small intestine Very Low Density Lipoproteins (VLDL) - ANS - Made from chylomicrons & repackages (in liver) - Smaller proportions of triglycerides greater proportion of cholesterol - Transports triglycerides to most cells - As they dump the triglycerides, they get smaller - Turn into low density lipoproteins - synthesized in liver Low Density Lipoproteins (LDL) - ANS - Made from VLDL - Smaller proportion of triglycerides greater proportion of cholesterol - Transports cholesterol to cells to make hormones And build new cell membranes - Liver regulates cholesterol (removes it from blood) - Too much causes a lot of problems! (Stay tuned) High Density Lipoproteins (HDL) - ANS - Not made from LDL - Made by the liver - Removes cholesterol from cells (Carries it to liver and gets recycled/disposed) - Too little isn't helpful - synthesized in liver Does the type of dietary fat alter the lipoproteins? - ANS - yes - Saturated fats lead to the most circulating VLDL & LDLs - Polyunsaturated (PUFA) and monounsaturated (MUFA) have the least Which lipoprotein is strongly associated with cardiovascular disease risk, stroke and mortality? - ANS Fed state (abundance/surplus - after meals) - ANS - Store energy for later use; most efficient place to store this: adipose (fat) tissue - Use as immediate energy in: muscle tissue - Lipoprotein lipase (LPL) hydrolyzes TGs -> FAs - FFAs then enter the muscle and/or adipose Muscle: FFAs -> energy Adipose: FFAs -> TGs (fat) P a g e 27 | 40 - % daily value: how much a food contributes to daily fat intake -- Based on: 2000 calorie diet, 35% AMDR for fat = 78 grams/day -- Varies by personal daily calorie intake and fat AMDR (20-35%) - % calories from fat: percentage of a food's total calories that come from fat -- No longer shown on new labels Guidelines for Fake Intake - ANS - Type of fat may be more important than amount of fat - Limit saturated and Trans fat intake - Consume enough beneficial fat for health - DRI recommendations: -- Moderate calories from fat (20-35%) -- Compatible with low rates of disease Olive oil - ANS - Benefits for heart health: reducing LDL cholesterol -> domino effect - Canola and safflower oil = also healthy options - Instead of saturated fats (e.g. butter, stick margarine, animal fats) Nuts - ANS - Fat composition: 80% calories from fat -- 59% monounsaturated; 27% polyunsaturated; 14% saturated - Benefits for heart health: reducing LDL cholesterol -> domino effect - Beware of added sugars and sodium - Instead of other high-fat snack options Fish - ANS - Omega-3 fatty acids -- Benefits for heart health - Beware of environmental contaminants (e.g. mercury) - Instead of fatty meats -- Recommendation: 8 oz. /week Saturated fat = determinant of LDL cholesterol - ANS - Sources of saturated fat in US: fatty meats; whole milk products; tropical oils - Zero saturated fat is not possible - Vegan/Vegetarian diets can lower saturated fat Trans fat - ANS Limit hydrogenated foods (processed and convenience foods) The Mediterranean Diet - ANS - Eating pattern: -- Low in saturated fat and very low in Tran’s fat -- Rich in unsaturated fat, complex carbohydrates, fiber, phytochemicals, and other nutrients -- US restaurants aren't the same... - High fat consumption but low heart disease risk Main Roles of Proteins - ANS 1. Growth and maintenance 2. Enzymes 3. Hormones (some) 4. Regulators of fluid balance 5. Acid-base regulators 6. Transporters 7. Antibodies 8. Energy/Glucose Growth and maintenance - ANS - Building blocks for most body structures - Allows for movement and function - Major structural component of all cells in the body - Collagen (protein): most abundant protein in the body -- Material for ligaments and tendons -- Basis of bone and tooth formation -- Provides the "glue" between cells of artery walls (withstand pressure from pumping blood) -- Tissue repair (scars) P a g e 30 | 40 - Replacement of dead or damaged cells -- Average life of skin cell is 30 days -- GI tract cells turn over every few days Enzymes - ANS - Break down (catabolic) substances - Build up (anabolic) substances - Transform substances - Enzymes = catalysts -- Facilitate reactions -- They remain intact Hormones (some) - ANS Examples: insulin Messenger molecules Transported in blood from glands to target tissues Elicit responses in target tissues to maintain homeostasis Acid-base regulators - ANS Proteins = buffers that maintain acid-base balance in body Transporters - ANS - Carry nutrients/other molecules (e.g. hemoglobin) - Cell membrane "pumps" Antibodies - ANS - Defend body against - Body detects antigens (invaders) and makes antibodies (protein molecules that combat specific antigens) Energy/Glucose - ANS Starvation or insufficient CHOs: PRO -> AAs -> Energy Priority: help maintain blood glucose (which may cost lean body tissue) Amino acids (AAs) are the building blocks of protein - ANS - AAs Atoms: -- Carbon ©, hydrogen (H), oxygen (O)...just like CHO and lipids -- Plus: nitrogen (N): amino = nitrogen-containing - AA structure: -- Central carbon © with four bonds -- (H) One hydrogen -- Amino group (NH2) -- Acid group (COOH) -- Unique side group for each amino acid Twenty different amino acids - ANS - Similar chemical structure - Different characteristics (side groups): size, shape, electrical charge Essential amino acids (n=9) - ANS - Body needs but cannot make - Essential to derive them from food Nonessential amino acids (n=11) - ANS - Body can synthesize - Present, but not needed in the diet Peptide bonds connect amino acids to form proteins (condensation) - ANS - 2 AAs bonded: dipeptide - 3 AAs bonded: dipeptide - 4+ AAs bonded: polypeptide - Most proteins contain 10s to 100s of AAs Building Proteins - ANS 1. DNA (carries PRO info.) 2. Transcription (1 DNA strand -> mRNA) 3. Translation (mRNA -> Tran (AAs)) 4. Protein formation Breaking down proteins (denaturation) - ANS - Exposure to heat, acid, other conditions - Disruption of polypeptide bonds - Protein structure uncoils, loses its shape and stability -- Lose functionality P a g e 31 | 40 -- Irreversible at certain point -- Examples: curdling milk (acid); cooking eggs (heat); digesting proteins in stomach (acid) PRO Digestion and Absorption - ANS Ultimate goal: break ingested foods into smaller molecules PRO digestion in mouth - ANS nothing Where does most protein digestion occur? - ANS PRO digestion in stomach - ANS - Small amount of digestion (10-15%) - HCI & inactive enzyme (pepsinogen) - Pepsinogen - HCI -> pepsin (no 'as') - Polypeptide molecules - Pepsin -> smaller polypeptide chains free AAs PRO digestion in small intestine - ANS - Pancreas and small intestine -> proteases and peptidases - (Large) polypeptides - proteases -> tripe tides, dipeptides, AAs - Di & tripe tides - peptidases -> AAs PRO digestion in large intestine - ANS nothing Protein absorption - ANS Peptides can either be 1) broken down into smaller peptides or AAs or 2) transported into the intestinal cells -- Di & tripe tides can be transport without energy -- AA transporters: (like glucose) require energy - Inside the cell, di & tripe tides can be broken down into AAs - Many AAs are used by small intestine - Unused amino acids transported to liver -- Some AAs bypass liver (BCAAs) Protein metabolism - ANS - goal: have enough PRO for functional needs (see protein roles) - Pro turnover (pro formation vs. pro breakdown) = nitrogen balance - (-) nitrogen balance: nitrogen (in) vs. nitrogen (out) - used for protein requirements - Nitrogen balance: nitrogen out > nitrogen in -- Severe stress: starvation, burns, infections, fever, injuries -- leads to muscle wasting - (+) nitrogen balance: nitrogen in > nitrogen out -- occurs with higher protein diets -- may be beneficial for muscle gains, etc. Protein turnover - ANS unlike CHOs or lipids, AAs are NOT stored - When AA deficient (- nitrogen balance), the body breaks down less critical protein - Small supply in blood and body cells (amino acid pool) - used for: energy, glucose, fat, ketone bodies Protein metabolism: ammonia production - ANS - Generated as a result of amino acid metabolism - Toxic compound and needs eliminated - Liver can convert it to urea (non-toxic) - Kidneys filter urea out of blood and into the urine Health effects: pro deficiency - ANS - too little total protein or lacking essential amino acids SIGNIFICANT IMPACT ON CHILDREN AND ADULTS: - Reduced growth (Muscle, Bone) - Reduced physical function (Weakness, Fatigue) - Increased hunger/reduced fullness - Reduced cognitive function P a g e 32 | 40 -- Food pairings that make a complete protein: beans and rice, legumes with grains, nuts, seeds or dairy, grains with dairy, dairy with nuts, dairy with nuts/seeds and legumes From Guidelines to Groceries - ANS - Mix n match protein sources (even with animal sources) - Target foods lower in saturated fat -- Grill/cook with saturated fat in mind - Be mindful of protein quality - Be mindful of portion size -- More is not always better -- Closed fist -> 4-6 oz. meat (ideal) Protein supplements - ANS - In general, most Americans can achieve even optimal PRO amounts with diet - To build/maintain lean mass, protein supplements can be part of a healthy diet: -- 3 food based meals/d -- 1-2 protein supplements/d - Recommended in those following a vegan diet to achieve RDA amounts! - Protein type recommendation: -- 1 scoop = 24-30 g high quality PRO -- Fast-digesting -- Can have GI issues if allergic -- Drink lots of water -- Pay attention to other ingredients Energy - ANS - Heat: body temperature - Mechanical: movement - Electrical: nerve impulses - Chemical: storied in food and body (powers cellular activity) Metabolism - ANS Release of energy, water and carbon dioxide (as waste) from chemical bonds Energy metabolism - ANS How body obtains and uses energy from food Liver cells - ANS - Most versatile and metabolically active - Superhero! First to receive nutrients and toxins Anabolism - ANS - Buildup of body compounds (e.g. condensation) - Requires energy Catabolism - ANS - Break down of body compounds (e.g. hydrolysis) - Releases energy Transfer of energy in reactions: ATP - ANS Energy is released during breakdown of glucose, fatty acids and amino acids = captured by compound Adenosine triphosphate (ATP) Contains three phosphate groups - Negative charge (vulnerable to hydrolysis; H+) - Hydrolysis: bonds between phosphates break = energy released Provides energy for all cell activities *Coupled reactions* - ATP releases energy + reaction that will use energy: transfer energy from catabolic -> anabolic - Food -> ATP = 50% efficiency - Heat loss: food -> ATP; ATP -> body's work Enzymes - ANS - Facilitate metabolic reactions - Protein catalysts (do not change, themselves) Coenzymes - ANS - Organic molecules; NOT proteins P a g e 35 | 40 - Associate with specific enzymes ("little helpers") - Without coenzyme, an enzyme cannot function Digestion review - ANS - Carbohydrates -> glucose (and other monosaccharide’s) - Fats (triglycerides) -> glycerol and fatty acids - Proteins -> amino acids Molecules: glucose, glycerol, fatty acids and amino acids - ANS - Composed of atoms: carbon, nitrogen, oxygen, hydrogen - Catabolism: bonds between atoms break = release energy Two new compounds of metabolism - ANS Pyruvate - 3-carbon structure - Glucose, amino acids, and glycerol -> pyruvate - Can be used to make glucose Acetyl CoA - 2-carbon structure - Fatty acids -> acetyl CoA - Cannot be used to make glucose - Enters TCA cycle - Energy harnessed through electron Glucose (C6H12O6) -> pyruvate - ANS Glycolysis - "Glucose-splitting" - One glucose molecule (6 C) becomes 2 pyruvate molecules (3 C each) - Hydrogen atoms (H+) carried to an electron transport chain Pyruvate can be converted back to glucose if needed - Primarily by liver cells (kidneys) - Process = similar to glycolysis reversal Pyruvate's options - ANS Quick energy needs (e.g. sprint): anaerobic - Not requiring oxygen - Pyruvate -> lactate - Energy does not equal sustainable Slower energy needs (e.g. 10k): aerobic - Requiring oxygen - Pyruvate -> acetyl CoA - Greater energy yield (can be sustained) Pyruvate -> lactate (anaerobic) - ANS At rest: occurs to a limited extent During high intensity exercise (e.g. sprint) - Increase in pyruvate (produces ATP quickly) - Excess of H-carrying coenzymes (overwhelms mitochondria in cells) and electron transport chain can't accept H, so... Pyruvate accepts hydrogen’s - (also due to lack of oxygen in cells) - Converts pyruvate to lactate - Coenzymes are released to pick up more H to continue glycolysis Accumulation of lactate in muscles coincides with: - Drop in blood pH, burning pain, fatigue Cori cycle: possible fate of lactate - ANS Transported from muscles to liver - Liver converts lactate -> glucose - Glucose returned to muscles Pyruvate -> Acetyl CoA (aerobic) - ANS During low intensity exercise (e.g. 10k) - Oxygen and mitochondria are available - H+ can be carried by coenzymes to electron transport chain Pyruvate enters mitochondria of cell - Carbon group removed (becomes carbon dioxide) - 2-carbon compound joins with CoA; becomes acetyl CoA Irreversible (cell can't retrieve carbons from CO2 to remake pyruvate) P a g e 36 | 40 Breaking down Nutrients for Energy: Glycerol and Fatty Acids - ANS Triglycerides: glycerol and fatty acids Glycerol -> pyruvate (or glucose) - Glycerol (3-carbon compound): can easily be converted to glucose or pyruvate (-> acetyl CoA) Fatty acids -> acetyl CoA - Cannot be used to synthesize glucose - Fatty acid oxidation: Fatty acids dismantled 2-carbon units at a time 2-carbon compounds join with CoA -> acetyl CoA As carbons break off, associated hydrogen’s and electrons (H+) carried to electron transport chain Breaking down Nutrients for Energy: Amino Acids - ANS First step: deamination - N-containing amino group is lost - Produces ammonia + keno acid Amino acid -> energy pathway - Converted to pyruvate (glycogenic) - Converted to acetyl CoA (ketogenic) - Enter TCA cycle directly (glycogenic) Amino acids -> glucose - When carbohydrates are unavailable Acetyl CoA's options (final steps of metabolism) - ANS Synthesize fats - If ATP = abundant - Most efficient way to store energy - All energy nutrients can become ATP = all excess energy nutrients can become fat Generate high-energy compound ATP - If cells need energy and if ATP = low - Process through TCA cycle: inner compartment of mitochondria - Release hydrogen’s and their electrons (H+) -> electron transport chain TCA cycle - ANS Final common metabolic pathway for energy nutrients Circular path (one way) - Acetyl CoA (2-carbon compound) travels one way and releases: - Two carbon dioxide molecules (CO2) - One CoA enzyme - Hydrogen atoms and their electrons (H+) -> carried off by coenzymes (made from niacin and riboflavin) to electron transport chain Oxaloacetate: 4 carbon compound made primarily from pyruvate - Needed to initiate first step and synthesized in last step of cycle - Must be available for acetyl CoA to enter cycle Electron transport chain - ANS Captures energy in bonds of ATP Series of proteins - Electron "carriers" mounted in sequence - Inner membrane of mitochondria Coenzymes deliver electrons - From TCA cycle, glycolysis, and fatty acid oxidation - Electrons passed to next carrier, and next carrier, and next carrier, until... - Oxygen is reached at end of chain (necessary for energy metabolism): Oxygen accepts electrons, combines with H atoms = H2O released - ATP synthesis powered by H ions: pumped out of inner compartment, then rush back in Fat is - ANS - The most efficient fuel source - Body's preferred form of energy storage Fat yields most energy per gram (9 calories vs. 4) - ANS - Fatty acid bonds = mostly between C and H - Oxygen added to form CO2 and H2O -> P a g e 37 | 40