Nutrition 2015 Exam 2 Study Guide
Nutrition 2015 Exam 2 Study Guide 2105
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This 15 page Study Guide was uploaded by Veronica Fostik on Sunday February 28, 2016. The Study Guide belongs to 2105 at East Carolina University taught by Kimberly Lukhard in Spring 2016. Since its upload, it has received 118 views. For similar materials see Nutrition Science in Nutrition and Food Sciences at East Carolina University.
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Date Created: 02/28/16
NUTR 2015 CH 5 Food Choices Poor health from too much/too little fat Poor health Lipids Triglyceride- glycerol & 3 fatty acids Fatty acids- even number of carbons & saturated/unsaturated Phospholipids Sterol Chemist’s View of Triglycerides & Fatty Acids more carbons & hydrogens per gram (energy) Fatty acids o Organic o Methyl group & acid group o Even number of carbons (18 carbon fatty acids in food) o Saturated- full of hydrogens o Unsaturated- lacking hydrogens o Double bonds near methyl end (omega number) o Linoleic acid o Monounsaturated fats (omega- 9 group) Triglycerides o Glycerol backbone o 3 fatty acids o Condensation reactions form them o Mixture of fatty acids Glycerol + 3 fatty acids triglyceride + 3 water molecules Degree of unsaturation o Firmness- length of carbon chain (polyunsaturated fats & unsaturated fats) o Stability- oxidation & spoilage of fats o Hydrogenation o Trans-fatty acids Chemist’s View of Phospholipids & Sterols Phospholipids o soluble in water & fat o emulsifiers/ part of cell membranes o lecithin Sterols o Cholesterol & plant sterols o Body compounds made from cholesterol Lipid Digestion Fats are hydrophobic Digestive enzymes are hydrophilic Fat digestion dismantles triglycerides (monoglycerides, fatty acids & glycerol) Mouth o Lingual lipase Stomach o Muscle contractions o Gastric lipase Small Intestine o Cholecystokinin (CCK)- gall bladder releases bilebile is emulsifier o Pancreatic lipase o Hydrolysis (triglycerides & phospholipids) Bile Roots o Blood cholesterol levels o Bile is stored in GALLBLADDER o Bile emulsifies fats in SMALL INTESTINE o Bile reabsorbed back into blood o Bile is made from cholesterol in LIVER o Bile trapped by soluble fibers excreted in feces in COLON Lipid Absorption Directly in bloodstream o Glycerol & short/medium chains of fatty-acids Lymphatic system o Micelles diffuse into intestinal cells o Triglycerides reassemble o Lots of proteins- chylomicrons o Bypass liver Lipid Transport Lipoproteins 1. Chylomicrons- largest & least dense a. Transport diet-derived lipids b. Liver removes remnants from blood 2. Very Low density lipoproteins (VLDL) a. Made in liver b. Proportion of lipid shift 3. Low density lipoproteins (LDL) a. Supports cell needs b. Liver regulation 4. High density lipoproteins (HDL) a. Remove cholesterol from from cells b. Carry cholesterol to liver to recycle c. Anti-inflammatory properties Role of Triglycerides PROVIDE CELLS WITH ENERGY (9 kcal/g) o Unlimited ability to store fat energy in body Adipose tissues- secrete hormones (adipokines) Skin insulation, shock absorption, cell membranes & cell signaling pathways Essential Fatty Acids Linoleic acid- omega 6 fatty acid Linoleic acid- omega 3 fatty acid (DHA, EPA- eicosanoids) Fatty acid deficiencies Lipid Metabolism Adipose cells store fat after meals o Lipoprotein lipase (hydrolyzes triglycerides) o Triglycerides reassembled in adipose tissues Uses fat for energy o Protein sparing o Energy deprivation (fasting & ketone bodies) Health Effects of Lipids Heart disease o High blood cholesterol (saturated fat & trans fats increase LDL cholesterol) o Monounsaturated fats- replace saturated & trans fats Reduces blood cholesterol o Omega 3-fatty acids Omega 6:3 ratio Cancer o Promotion instead of initiation o Dietary fat & risks for each type of cancer Obesity o Cutting fat from diet lowers kcalories Recommended Intake of Fat Eat low amounts saturated & trans fats Eat low amounts of cholesterol 20-35% of fat in diet per day DV is on labels for saturated fat & cholesterol Risk of insufficient fat intake Guidelines Vitamins A, D, E,K are fat-soluble Alternatives for meats Specific milk & milk products Vegetables, fruits & grains lower consumption of fat Invisible fat- fried & baked goods Don’t eat lots of processed foods Fat replacers Compare products Olive oil has benefits for heart health o Replaces saturated fats Nuts have LDL cholesterol o Fat composition Fish has Omega 3-fatty acids o Beware of contaminants Saturated fats in foods o Meats, whole milk products, tropical oils o Zero saturated fat doesn’t exist Trans fat- limit hydrogenated foods Mediterranean Diet is low in all fats & rich in fiber, carbs, & nutrients Misc Human body uses longer chain Omega 3’s & Omega 6’s to make substances: eicosanoids o Eicosanoids are hormone like compounds- only affect the cells where they are made or near & have different effect on each cell o Eicosanoids made from Omega 3 fatty acids Help decrease blood pressure, prevent clot formation, reduce inflammation & protect against irregular heartbeat o Eicosanoids from Omega 6 fatty acids Promote clot formation, inflammation, & blood vessel constriction Omega 6 acids protect heart by decreasing LDL levels & increasing insulin resistance Foods rich in Omega 3 fatty acids o Fish, fish oils, flaxseeds & chia seeds Foods rich in Omega 6 fatty acids o Vegetable oils, fat food products packaged goods, crackers, cookies, cakes & chips o Need 1:1 ratio but most Americans eat 20:1 ratio of Omega 6 to Omega 3 fatty acids Adipokines- hormones secreted by fat cells o Help regulate energy balance & help body functions o When weight changes, so do Adipokines o Adipokine resistin increases in obesity o When you lose weight, Adiponectin produced which prevents diabetes Fat o Excess fat stored in adipose cells for later use o LDL’S are bad BAD cholesterol o HDL’s HEALTHY cholesterol Lipoprotein lipase breaks apart triglycerides from lipoproteins in blood CH 6 Proteins Atoms: carbon, hydrogen, oxygen, nitrogen Amino acids: carbon, hydrogen, amino & acid group, side group More complex than fats or carbs 21 amino acids o each have different characteristics o essential amino acids Peptide bonds link amino acids o condensation reactions Amino acid sequencing o Amino acid sequence determines shape of polypeptide chain o Primary structure: chemical bonds o Secondary structure: electrical attractions o Tertiary structure: hydrophilic & hydrophobic o Quaternary structure: 2 or more polypeptides 4 highly folded polypeptide chains form globular hemoglobin protein Denaturation o Disruption of stability o Uncoil & lose shape o Stomach acid Protein Digestion Mouth Stomach o Hydrochloric acid denatures proteins o Pepsinogen to pepsin Small Intestine o Hydrolysis reactions o Peptidase enzymes Protein Absorption Transport into intestinal cells Unused amino acids transported to liver Enzyme digestion Predigested proteins Protein Synthesis Uniqueness or each person Amino acid sequences of proteins o Genes- DNA Want to have adequate protein in diet DNA template to make mRNA o Transcription mRNA carries code to ribosome o ribosomes are “protein factories” mRNA specifies sequence of amino acids o Translation- tRNA There can be sequencing errors Gene expression & protein synthesis o Capability of body cells o Protein needs Dietary influence on gene expression determines diseases Roles of Proteins Growth & maintenance o Building blocks for most body structures (collagen) o Replacement of dead or damaged cells Enzymes o Break down, build up, & transform substances o Catalysts o Each enzyme facilitates specific chemical reaction Hormones o “messenger molecules” o transported in blood to target tissues Regulators of fluid balance o Edema Acid-base regulators o Attract hydrogen ions Transporters Antibodies o Defend body against disease o Immunity- memory Energy & glucose o Starvation & insufficient carb intake (waste of lean body tissue) Protein Metabolism Protein turnover & amino acid pool o Continuous production & destruction o Amino acid pool is always constant Used for protein production Used for energy (if no nitrogen) Nitrogen balance o 0 nitrogen balance o positive & negative nitrogen balance Making other compounds o Neurotransmitters, melanin, thyroxin, niacin Making fat o Energy & protein exceed needs o Can cause weight gain Deaminating amino acids o No nitrogen-containing amino acid group Ammonia & keto acid o Body can transfer amino groups from an amino acid to keto acid, forming new nonessential amino acid & new keto acid Transamination needs B6 vitamin coenzyme Make proteins & nonessential amino acids o Breakdown of proteins, keto-aicds, liver cells Converting ammonia to urea o Liver- ammonia & carbon dioxide o Liver releases urea into blood o Kidneys then filter urea out of blood o Liver & kidney disease o Protein intake & urea production depends on water consumption Protein Quantity 2 factors: digestibility & amino acid composition Digestibility o Foods consumed o Animal vs plant proteins Amino acid composition o Essential amino acid consumption & nitrogen-containing amino groups Reference protein (pre-school children) High-quality proteins o Animal vs plant proteins Complementary proteins o Low-quality proteins combined to provide adequate levels of essential amino acids Protein Regulations for Food Labels Amount of protein in grams % Daily value Protein-Energy Malnutrition (PEM) Insufficient intake of protein can lead to malnutrition & low energy Children can have poor growth if malnourished Loss of muscle or excessive weight loss Marasmus (for age) o Chronic PEM o Children 6-18 months, people in poverty, skin & bones (old people) o Impaired growth, wasting of muscles, impaired brain development, lower body temp o Improper digestion & absorption Kwashiorkor o Acute PEM o Children 18 months to 2 years (develops rapidly) o Aflatoxins o Edema, fatty liver, inflammation, infections, skin & hair changes, free-radical iron, major weight loss, loss of appetite Marasmus-Kwashiorkor mix Infections are high o Degradation of antibodies to protect against o Heart failure & death Rehab o Rehydration & nutrition intervention-add protein slowly back into body Health Effects of Protein High-protein diets can cause disease o Heart disease, cancer, kidney disease, osteoporosis (calcium excretion goes up) Recommended Intakes for Protein Have an adequate amount in diet- differs for everyone 10-35% of daily intake Adults: 0.8g/kg of body weight/day Serving sizes- don’t overeat (moderation) Protein powders Muscle work vs protein supplements o Athletic performance o Whey protein (complete protein that contains all 9 essential amino acids) Promotes muscle growth & growth of lean tissue Amino acid supplements o Can be risky if take too much o Lysine & tryptophan CH 7 Metabolism Energy metabolism is all the ways the body obtains & uses energy from food Ultimate source of energy = Sun Photosynthesis: plants make simple sugars from CO2 & capture sun’s light energy in chemical bonds of sugars o Humans then eat plants or animals & get energy Cells always doing metabolic work Reactions Anabolism- building up of body compounds Anabolic reactions make glycogen, triglycerides & protein Catabolic reactions are the BREAKDOWN of glycogen, triglycerides & proteins o Release energy Some energy released in catabolic reactions (breakdown) is captured in ATP o ATP= high- energy compound Hydrolysis of ATP occurs at same time with reactions that use the energy it releases o Coupled reactions- energy from breakdown of one compound is used to create bond for another compound Body uses ATP to transfer energy Body converts chemical energy from food into chemical energy of ATP Enzymes are required for metabolic reactions o Enzymes facilitate reactions o Enzyme helpers= coenzymes Breaking Down Nutrients for Energy During digestion, body breaks down energy-yielding nutrients into smaller molecules to be absorbed o Carbs= glucose o Fats (triglycerides) = glycerol & fatty acids o Proteins= amino acids During catabolism, bonds between atoms break, releasing energy Pyruvate can be used to make glucose o Amino acids & glycerol can be converted into Pyruvate so they CAN make glucose Acetyl CoA CANNOT be used to male glucose o Fatty acids are converted into Acetyl CoA, so they CAN’T make glucose o Acetyl CoA can make fat Glucose fuels most energy of central nervous system & red blood cells o Without glucose, body break’s down own lean tissue (protein containing) to get amino acids needed to make the glucose To protect protein tissue, body needs carbs Eating only fat foods makes abundant Acetyl CoA & makes body break down tissue to get glucose Eating only protein makes body convert protein in glucose Want to have balance of carbs & protein Glucose Glycolysis is first pathway glucose takes to yield energy o Glucose splitting o Net yield of energy is small to start glycolysis & releases only a little more than was put in Glucose breaks down into Pyruvate If needed, cells in liver can make glucose from pyruvate in process that’s similar to reversal of glycolysis Whenever carbs, proteins, & fats are broken down, oxygen ALWAYS involved Anaerobic When body needs energy quickly (sprinting) pyruvate is converted to lactate o Breakdown of glucose to pyruvate to lactate is made without oxygen- ANAEROBIC Pyruvate to lactate: if electron transport chain is unable to accept hydrogens, there is a lack of mitochondria in the cells o If lack of oxygen, pyruvate can accept hydrogens, so pyruvate becomes lactate During high intensity exercise, muscles rely heavily on anaerobic glycolysis to produce ATP fast so lactate can increase o Coenzymes released so glycolysis can continue Anaerobic path yields energy quickly, but doesn’t last long Build up on lactate in muscles can lead to lower blood pH, burning pain, or fatigue Lactate transported to liver, where lactate is returned to muscles (Cori cycle) Aerobic Energy that takes a while to release but lasts a while (run around track)- AEROBIC o Pyruvate breaks down into acetyl CoA Pyruvate to acetyl CoA When cells need energy & oxygen is available, pyruvate molecules go into mitochondria of cell o Eventually becomes acetyl CoA Carbon group from pyruvate becomes CO2, which is released into BLOOD, circulated to LUNGS, and breathed out Glycerol & Fatty Acids Triglycerides breakdown into glycerol & fatty acids Glycerol to pyruvate: then into acetyl CoA Fatty acids to acetyl CoA: fatty acids taken apart 2 carbons at a time in reactions called fatty acid oxidation o Hydrogens & electrons released & carried to electron transport chain by coenzymes made by riboflavin & niacin (Vitamin B) Fatty acids CANNOT MAKE GLUCOSE Red blood cells, brain & nervous system rely on glucose as FUEL When carbs unavailable, liver makes glucose from pyruvate & glycerol Amino Acids Amino acids lose nitrogen containing amino groups before going into metabolic pathways Deamination makes ammonia that provides nitrogen needed to make nonessential amino acids o Remaining ammonia cleared from body by urea synthesis & in the liver & excretion in kidneys Amino acids can enter pathway in many ways (acetyl CoA or pyruvate) Final Steps of Energy Metabolism When ATP is abundant, acetyl CoA make fat- most efficient way to store energy for later use When ATP is low & cells need energy, acetyl CoA can go through TCA cycle, releasing hydrogens with electrons to electron transport chain TCA cycle is final metabolic pathway for carbs, fats & amino acids TCA cycle is circular path bc oxaloacetate is needed in first step and synthesized in the last When oxaloacetate is insufficient, TCA cycles slows down and cells don’t get enough energy Oxaloacetate made from pyruvate & can’t be made from fat Oxaloacetate must be available for acetyl CoA to enter TCA cycle Diet with good supply of carbs, means adequate supply of oxaloacetate Electron transport chain captures energy in the high-energy bonds of ATP Electron transport chain consists series of proteins that act as electron carriers As electrons passed from carrier to carrier, hydrogen ions are pumped across membrane to outer compartment of mitochondria o Energy is captured in bonds of ATP o ATP leaves mitochondria and enters cytoplasm where it’s used for energy Fat provides most energy per gram Feasting Feasting= excess energy o When person eats too much o Metabolism favors fat formation o Fat cells enlarge Excess protein- person can’t grow muscle if there’s too much protein; increases oxidation Excess carbs- creates fat; increases oxidation Excess fat- excess dietary fat moves into body’s fat stores Fasting Carbs, protein, & fats are used for energy fuel Glucose from liver’s stored glycogen travel to cells Gluconeogenesis- making of glucose from noncarbohydrate sources o Liver is major site o Kidneys become involved- starvation Ketone bodies- acidic compounds produced by liver during incomplete breakdown of fat when carbs aren’t available When keto acid concentration rises, pH of the blood drops Conserving energy- hormones of fasting slow metabolism o As body shifts to use of ketone bodies, simultaneously reduces energy its energy output & conserves fat & lean tissue Low Carb Diets Metabolism of fasting diet Body uses glycogen stores to provide glucose glucose for cells of brain, nerves, and blood Once body uses up all of the glucose, begins making glucose from amino acids of protein (gluconeogenesis) Low carb diet may provide abundant protein from food, but body still uses some protein from body tissues Glycogen depletion- monitor urine CH 8 Energy Balance & Body Composition Energy balance- energy consumed from foods & beverages compared with energy expended through metabolic & physical activities o Amount of body fat stored depends on energy balance Excess energy is stored as fat Store fat used for energy between meals o 50,000-200,000 kcalories of reserve energy When person maintains weight, energy in = energy out 3500 kcalories eat in excess = 1lb fat stored Lower energy intake by 500/day to lose 1lb fat/week Retention or loss of water can cause weight gain During starvation, losses of fat & lean are = Energy In- Calories Foods Provide How much energy person receives depends on composition of foods & beverages and amount people eat & drink Bomb calorimeter is how we figure out how many calories food provides o Food is burned, energy is released in form of heat, which gives measure of food’s energy value o Create CO2 & water Physiological fuel value is the amount of energy that human body derives from foods Energy of foods can be found from amount of carbs, proteins and fats Food Intake To achieve energy balance, body must meet needs without taking in too much or too little Appetite prompts people to eat/not eat Hunger- painful sensation caused by lack of food (physiological response) o Hypothalamus (nerve signals & chemical messengers) o Hypothalamus controls all feelings of hunger & satiety o Absence or presence of nutrients in bloodstream Stomach is where food stays for 4-hour intervals Satiation happens when receptors in stomach stretch & hormones become active=full o “Stop eating” Satiety suppresses hunger- makes person not eat for a while o “Don’t start eating again” Boredom & anxiety can trigger hunger o Weight gain Large portions, favorite foods, or abundance of foods increases energy intake Satiation depends on nutrient composition of food o Protein is most satiating o Foods with higher energy density are more kcalories Energy Out Expend energy when physically active and while resting Basal metabolism is supported by 2/3 of daily energy o Lungs, bone marrow making new RBC’s, heart beating, & kidneys filtering waste Basal metabolic rate- rate which body expends energy for life- sustaining activities More person weighs, more total energy is expended basal metabolism o Energy per pound is lower BMR is highest when person is growing Lean body mass is physically fit people & males Physical activity is most variable component of energy expenditure o Muscles need extra energy to move & lungs/heart need extra energy to deliver nutrients & oxygen while disposing wastes Energy needed depends on MUSCLE MASS, BODY WEIGHT, & ACTIVITY When person eats, GI tract muscles speed up contractions & secret digestive juices become active o Some nutrients require energy to be absorbed Acceleration of activity requires energy & produces heat= thermic effect of food (TEF) o Proportional to food energy taken in & estimated at 10% of energy intake o Eat 2000 calories, expends 200 kcalories of TEF Additional energy expended when body changes are dramatic Body challenged to physical conditions (extreme cold, starvation, trauma) must adapt- do extra work & use extra energy to cope with demand o Adaptive thermogenesis Estimating Energy Requirements Depends on gender, growth, age, physical activity, and body composition & body size Body Weight & Composition Water, lean tissues (muscles & organs) & fats make up body composition o Body weight= fat + lean tissue (includes H2O) Athletes can weigh more than people with more body fat because muscles weigh more than fat BMI describes relative weight for height o Weight(lb)/height (in)^2 x 703 o Reflects height & weight not body composition People mistakenly turn to friends & society to declare if they are overweight or underweight o False image for how women are supposed to weight- leads to eating disorders & unhealthy diets o “Ideal” body composition doesn’t always mean healthy Obesity is still risk factor of disease even if society accepted it o Heart disease, diabetes, some cancers Body Fat Distribution Depends on how much of weight is fat & where it’s located o Depends on person For athletes, want a lower % of body fat- enough to provide energy, support hormone activity insulate & protect body, but not have excess bulk Some people need more body fat depending on environment (Alaska vs Florida) Visceral fat- stored around organs of abdomen Central obesity- excess fat around trunk of body Subcutaneous fat- fat stored directly under skin (hips & thighs) Weight circumference is ideal way to determine central obesity & what health risks are associated with it BMI & waste circumference are cheap and easy Health Risks with Body Fat Higher BMI & weight circumference = higher rate of disease Being underweight can cause lack of essential nutrients the body needs & higher risks after surgery o Irregular menstrual periods & can become infertile o Can lead to birth defects of children while pregnant Being overweight can cause many diseases o Heart disease, sleep apnea, diabetes, high blood pressure, kidney stones, respiratory problems, infertility, and complications in pregnancy & surgery o Obesity is second to tobacco in causing early deaths Chronic inflammation in obese people leads to chronic diseases o Lipids fill adipose tissues & go into muscles and liver o Changes metabolism once fat gets into abdominal region (insulin resistance) Fit & Fat vs Sedentary & Thin Cardiorespiratory & muscle fitness are major roles in health Overweight but fit people have lower risks than normal unfit people who don’t do any physical activity Fit people less likely to gain weight over years
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