BPK/KIN110 FINAL NOTES (CH6-10) .docx

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Biomedical Physio & Kines
BPK 110
Diana Bedoya

CHAPTER 6Protein The Structure of Amino Acids and Proteins Amino Acid Structure  Protein building blocks = amino acids, in long folded chains  AA Contains an amino group, an acid group and a unique side chain o Side chain = vary in size and structure, what makes each AA unique!  AA has nitrogen, distinguishes them from carbs/fats  There are 20 AA – make up all protein found in nature o 9 are essential AA (needed but cant make) – body cannot make new proteins without breaking down existing proteins to provide for the lack of EAA o 11 are nonessential amino acids (made in body) o Under certain conditions – some cannot be synthesized in sufficient amounts – referred as conditionally essential amino acids – eg aa tyrosine can be made from eaa phenylalanine – but if someone has disease phenylketonuria, phenyloalanin cannot be coverted into tyrosine, which means tyrosine is essential, and phenylketones builds up in blood and can lead to brain damage Protein Structure  Protein synthesis = condensation reaction = remove water, two link together  AA are linked together by peptide bonds to form polypeptides.  To be a functional protein, it needs to fold into a specific structure with 3 or 4 levels of organization. So all proteins are polypeptides, but not all polypeptides are proteins. o Primary Structure: The polypeptide chain o Secondary structure: Hydrogen bonds between side chains in the polypeptide help form alpha-helices and beta pleated sheets o Tertiary structure – form by disulphide, hydrogen bonds, etc between side chains o Quaternary structure - binding of 2+ polypeptide chains together Denaturation  The shape of a protein is essential to its function! (eg long shape of muscle protein help overlap and shorten during contraction).  Denaturation = alteration of protein‟s 3D structure (tertiary or quaternary) thus loses its original function o Heat, acid, agitation can denature a protein - Ex. Cooking an egg o Eg enzyme protein salivary amylase enters stomach, acid causes structure to change, no longer digest starch) Protein Digestion and Absorption  * The protein‟s 3D structure must first be denatured and the polypeptide must be broken down into individual aa‟s to be absorbed  Mouth – chemical digestion (chewing); no protein-specific enzymes to chemically digest protein  Stomach o Hydrochloric acid denatures 3D structure (open folds structure to make polypeptide more accessible for enzymatic breakdown) o Enzyme pepsin to chemically digest protein, breaking peptide bonds  SI - Most digestion occur o Pancreas secret pancreatic proteases to digest protein o Brush border enzyme further digest polypeptides into amino acids, dipeptides and tripeptide o Absorption - AA is absorbed by active transport (use energy too), into mucosal cells – blood - liver  **Similar structure AA compete/share the same transport system – so overconsumption of one AA will slow the absorption of another Synthesizing Proteins  Our DNA contains the „recipe‟ for making all our body proteins o Genes (contains info for specific protein) regulate synthesis by turning on/off the code for each protein  When on, protein is made = gene is expressed  Our body will pick and choose from the amino acid pool in order to make up specific body proteins as needed o Amino acid pool = all the aa in body tissues and fluids that are available for use by body  Including aa from diet ++ from breakdown of body proteins  If lack NonEAA, we can synthesize that aa from a similar one, through process of transamination (take another AA, change it, to make into into another AA that I need)  If lack EAA, body break down own protein to obtain, if cannot be supplied, protein synthesis stops! o That missing aa is called “limiting amino acid” – because it limits the ability to make a specific protein Functions  Structure (collagen, ligaments hold bones tgt, tendons attach muscles to bones, hair, every cell, muscles)  Movement (protein actin and myosin in skeletal muscles, overlap and detach to contract and expand)  Enzymes – all enzymes are protein (without it, metabolism would be too slow to support life)  Transport – active transport (protein transporter allow things to move in and out of cells), hemoglobin (blood protein that transport oxygen), protein tracks in cells  Protection from disease o Antibodies are proteins - kill virus o Skin is mostly protein – protect from pathogen  Fluid Balance (protein are charged particles, attract water to keep in blood) o Edema may result with low blood protein levels – when water accumulate in tissues, causing swelling  A source of Energy o 4kcal/gram – minor source overall o Not enough carbs/fats – will breakdown body proteins to form ATP o Proteins must first be deaminated (remove nitrogen) first  can enter CR at pyruvate, Acetyl CoA, part of citric acid cycle, or electron transport chain o If excess in calories, aa goes to liver, converted into AA, store adipose tissues Protein in Health and Disease  Protein Malnutrition rare in Canada  Marasmus = protein AND energy deficiency – no fat storage, breakdown muscles for energy  Kwashiorkor = have energy but lack protein - fluid accumulation in the abdomen, fat accumulation in the liver High Protein Diet  Associated with weight loss = proteins more satiating, usually tgt with low carb diet so eat less overall  Building muscles = need protein to gain muscles (but beyond certain level no synthesis occurs, most get enough, protein supplements may be waste of $) Concerns:  Best documented concern – diet high in animal proteins BUT low in F/V, whole grains o More sat/total fat; less fibre  increase risk of heart disease, diverticulosis, cancer o Increased caloric consumption  increased risk of obesity  More waste product excreted in urine (becuz of excess nitrogen), can lead to dehydration, may increase progression of kidney failure in predisposed individuals  May increase calcium loss – but not necessarily cause bone loss  May increase risk of kidney stones  Proteins in foods may trigger intolerances or allergies Vegetarian Diets  Types o Semivegetarian – excludes red meat, but eat fish, poultry, diary products, eggs o Pescetarian – excludes all animals, but eat fish o Lacto-ovo vegetarian – excludes all animals, but eat eggs/ diary products (Milk cheese) o Lacto vegetarian – excludes animals and eggs, but eat diary o Vegan – excludes all food of animal origin  Benefits o Tend to have lower rates of: Heart disease, breast cancer, obesity, hypertension, diabetes (more conscious about diet, eat less sat fat) o Better for the environment (use field for crops instead of farming animals for years, animals emit gas by products) o Reduced risk of infection from food o May be cheaper o Reduces animal harm  Risk o Vitamin and mineral deficiencies o No animal foods = Vegans require vitamin B12 supplements o No milk = Calcium, vitamin D deficiencies may occur o Iron, zinc are poorly absorbed from plants o Omega-3 may be low in vegan diets Soy  Pro: is a complete protein, high in PUFA, fiber, vits/mins, phytochemicals, low in sat fat o High intakes associated with lower risk of CVD, diabetes II, osteoporosis, certain cancers  Against: it is genetically modified, may decrease thyroid hormone levels, may block absorption of other nutrients, o Isoflavones found in soy mimics estrogen  promote breast cancer if women already has, lower risk if do not have Meeting Protein Needs  Nitrogen balance: N intake = N output (the amount synthesized = amount broken down) o Negative NB: N intake < N output (eg illness, injury, burns, diet too low in protein) o Positive NB: N intake > N output (eg pregnant, lifting weights – more is made than is being degraded)  AMDR = 10-35% of Calories  RDA = 0.8 g/kg body weight *to maintain* o Pregnant women RDA +25g/d o Protein needs increase during infections, fevers, burns, surgery o Endurance/strength(more) athletes need 1.2-1.4g/kg body weight o Most athletes get enough as is  Younger of same weight = need more g/day Choosing Protein Wisely  Protein quality- measure of how well a food provides all the essential aa‟s o Assessed using the PDCAAS - protein digestibility corrected amino acid score o Takes into account digestibility of the protein  Animal products – higher PDCAAS o Are complete proteins (have all 9 essential aa‟s) o Have B vitamins, iron, zinc, calcium o Tend to be low in fiber, high in sat fat and cholesterol ( Increase risk of heart disease)  Plant source – lower PDCAAS o Are typically incomplete proteins (lack 1+ essential aa‟s)  ex. Legumes = the starchy seeds of plants that produce bean pods, including peas , peanuts, beans, soybeans, lentils) o Contain some B vitamins, iron, zinc, calcium (but is less absorbable) o Rich in fibre, phytochemicals, MUFAS/PUFAS  Protein Complementation - Combining proteins from different sources so that they collectively provide the required proportions of amino acids to meet the body‟s needs o Important for many vegetarians CHAPTER 7Vitamins Vitamins  Organic – have carbon – more complex than minerals  Provide no energy – but help us get energy, facilitate cellular respiration  Functions: o Do not help develop body structure o Prevent oxidative damage o Needed in small amounts to regulate body processes (micronutrient) Bioavailability  the rate and extent to which a nutrient is absorbed and used  Approx 40-90% of vitamins in food absorbed  Determinants o efficiency of digestion & time of transit through the digestive tract o previous nutrient intake & nutrition status o other foods consumed at the same time o method of preparation o sources of the nutrient o from foods versus supplements Minimizing Vitamin Loss  vitamins are organic = therefore susceptible to destruction by: Heat, UV light, Oxidation  prevent losses through: refrigeration, storing in airtight containers to reduce oxidation, wash V/F before cutting, steam vegetables in small amounts of water, avoid over cooking Fat vs Water Soluble Vitamins  Water soluble (B,C) o Absorb directly into blood o No transporter required o Excrete more often, require to consume more, Less chance of toxicity (unless supplements) o More in meat  Fat soluble (ADEK) o Absorb with lipids into lymph  Need fat to be absorbed – if eat little fat can lead to deficiency *esp A & D o Packaged into chylomicrons to transport o Build up in fat, Not easily excreted, Require less often, can lead to toxicity o More in grains Water Soluble Vitamins  The B Vitamins Function Primarily as Coenzymes o Facilitate cellular respiration – Bind to enzymes to activate them Thiamin Source Function Deficiency Toxicity  Pork  Facilitate cellular respiration as a part of a coenzyme  Weakness /  Legumes  Important for nerve function  Irritability  Needed for synthesis of neurotransmitters  Synthesis of ribose Group at risk of Deficiency o alcoholics = Wernicke-Kosakoff Syndrome = confusion, psychosis, memory disturbance o developing world = Beriberi = weakness, nerve degeneration, heart changes Riboflavin * can be destroyed by UV lights! – hence opaque milk cartons Source Function Deficiency Toxicity  Milk  Facilitate cellular respiration as a part of a coenzyme  Cracking of /  Spinach  Convert other vitamins into active forms! the lips  Poor wound healing * Deficiency: alcoholics = Ariboflavinosis Niacin (nicotinic acid) Source Function Deficiency Toxicity  Beef  Facilitate cellular respiration as a part of a coenzyme  Dementia  Headache  Legumes  Higher dose may lower LDL, raise HDL  Diarrhea  Nausea  Participate in synthesizing fatty acids and cholesterol * Toxicity - If over 250 mg/day = Niacin flush * Deficiency – Pellagra (dementia diarrhea dermatitis death) Pantothenic Acid  Pretty much found/needed everywhere  Deficiency, toxicity = rare Biotin Source Function Deficiency Toxicity  Yogurt  Facilitate cellular respiration as a part of a coenzyme  Nausea /  Nuts  Required for glucose synthesis  Hallucination  Required for lipid synthesis Vitamin B6 Source Function Deficiency Toxicity Severe nerve  Meat  Facilitate cellular respiration as a part of a coenzyme  Poor growth  Legumes  Synthesize hemoglobin  Anemia damage  Make neurotransmitters  Break down glycogen into glucose **Folate/ Vitamin B12 / Vitamin B6 Needed to Prevent Rise in Homocysteine Levels High levels can increase CDV disease! Folate – folic acid  Folate needed to be activated by b12  Folic acid can be from supplements Source Function Deficiency Toxicity  Yeast  Needed for synthesis of DNA  Anemia Mask b12  Legumes  Needed for AA metabolism  Poor growth deficiency  Important for rapidly dividing cells  Lower levels of homocysteine (w/ B12 & 6)  Deficiency disease in Adults = macrocytic anemia (problem with blood) o Red blood cell precursor   Folate adequate = normal cell division  red blood cells  Folate deficient = cells cannot divide, grows bigger becomes megaloblasts (large immature RBC), turn into macrocyte (large mature RBC)  Result: fewer mature BRC is produced, blood‟s oxygen carrying capacity is reduced! During pregnancy = Neural tube defects o Neural tube becomes brain and spinal cord for baby o So neural tube defects may lead to spina bifida (the round thing that forms at lower end of spine)  Mandatory fortification of folate into grains since the late 90‟s  50% decrease in NT defects since then (Canada) Vitamin B12 (cobalamin)  Intrinsic factor needed for B12 absorption – released in stomach Source Function Deficiency Toxicity /  Animal  Production of ATP from certain fatty acids  Anemia products  Maintain myelin sheath  Homocysteine  Milk  Lower levels of homocysteine (w/ B12) level rise  Required to activate folate (thus prevent macrocytic anemia) Deficiency disease o Pernicious Anemia = cannot absorb b12 becuz lack intrinsic factor o Vegans = B12 only in animals, so vegans at risk of deficiency o Atrophic gastritis = in elders, stomach acid decrease with age, less intrinsic factor is released, less B12 is absorbed Vitamin C (ascorbic acid) Source Function Deficiency Toxicity  Citrus fruits  synthesis/maintenance of collagen  Bleeding gum  Diarrhea  Red  Needed to synthesize neurotransmitters  Bleeding skin  nausea peppers  Needed to synthesize hormones, bile acids  Antioxidant (maintain the immune system, does not prevent colds, but may decrease their severity/length) *Deficiency disease = Scurvy (bleeding gums, tooth loss, bleeding under skin, joint pain) Antioxidants  Protect against oxidative damage by free radicals (generated by exercise, pollution, smoking) o FR = molecule that lacks, and steal electrons, damage structure and function  Oxidative damage associated with o Cancer, diabetes, heart disease, possibly Alzheimer’s and Parkinson’s o When aging, collagen breaks down due to oxidation  Eg Vitamin C prevents oxidation & have extra electron, which it donates to FR to stop oxidation Fat-Soluble Vitamins Vitamin A  Found preformed or in provitamin form in the diet o Retinoids (animals ) = Preformed Vitamin A (retinol, retinal, retinoic acid) o Carotenoids (plants) = Provitamin that can be converted into retinoids in the body  Beta-carotene = most common provitamin that can be converted into Vit A in the body  Carotenoids that aren‟t converted into retinoids can function as antioxidants Source Function Deficiency Toxicity  Carrots  Needed for Cell differentiation – thru its role in gen Night  Headache  Polar bear expression, turn gene on/off blindness  Nausea liver  Retinol important for normal fetal growth & bone  Poor growth remodeling *only from  Antioxidant = Carotenoids only!!! retinoids!  Retinal is part of rhodopsin, a visual pigment in the retina of the eye. * Deficiency – Xeropthalmia = eye disorder that are associated with vitamin A deficiency - Night blindness = early stage, reversible – inability to replease rhodopsin stores - If untreated can lead to permanent blindness * Toxicity – Only retinoid cause symptoms of toxicity! – Carotenoids can cause hypercarotenemia (skin turn orange) Vitamin D  Source of (inactive) vitamin D o Sunlight  vitamin D precursor  Inactive Vita D o Diet  Inactive Vita D  To become active, must be modified by  liver  then by kidney o At Intestine = Active Vitamin D increase absorption of calcium and phosphorus from diet o At bone = increase bone breakdown, increase release of calcium and phosphorus into blood o At kidney = stimulates calcium retention, reduce amount excreted   all maintain normal blood levels of C & P  support bone mineralization! Source Function Deficiency Toxicity  Salmon  maintain normal level of calcium and phosphorus  weak bones  Nausea in body  Synthesis  muscle pain  kidney from  increase absorption of Calcium from diet damage sunlight  reduce calcium excretion at kidneys  increase release of calcium from bone * Major deficiency in Canada! o Deficient Vit D = decease calcium, break down bone to release calcium   Rickets (in children) = poor bone development, bend under pressure  Osteomalacia (adults) = weakened bones, loss of minerals  Increase risk of fractures (hips, spine)  Increase risk of osteoporosis = decrease in total bone mass * Toxicity (supplements) o Hypercalcemia = too much blood calcium, tissues (heart, lungs, liver) become calcified  Can die Vitamin E Source Function Deficiency Toxicity  Plant oils  Antioxidant role!! - reduce risk of cancer, heart disese Broken RBC  Rare, large  Leafy  Protects membranes in RBC, nerve cells  Nerve dose may interfere greens  Anti-inflammatory role – reduce LDL oxidation damage  Defend against damage by lead, mercury, toxins with blood o Individuals with the highest [vit E blood] have clotting lowest risk of death o BUT vit E supplements do not seem to have these benefits….adequate dietary Vit E is recommended * Deficiency – break down of cell membranes o RBC membranes rupture  lead to hemolytic anemia  Most common in premature infants  Rare in adults – only when fat absorption is compromised Vitamin K  Unlike other fat soluble vitamins – body uses vitamin K rapidly, need constant supply!!  Bacteria synthesize vitamin K, so long term antibiotic use can cause deficiency Source Function Deficiency Toxicity  Plant oils  Needed for production of several clotting factors!  Anemia /  Leafy  Needed for production of several proteins involved in  Brain damage greens bone remodelling (hemorrhage) Warfarin  Is an anticoagulant = prevents blood clotting  Used as a rat poison = make them bleed to death  Warfarin inhibits action of Vitamin K o Dicoumoral = A derivative of warfarin, used to treat heart attack patients, reduce blood clots in arteries Supplementation  Older adults (B12, vit D)  Vegans- if no dairy (B12, vit D, Calcium)  Alcohol users (B vitamins)  Infants and children (fluoride, vit D, iron)  Young Women/ pregnant women (400 µg of folate)  Dark-skinned indvs (vit D)  Smokers (Vit C, maybe E) Vitamin Water  Problems: o Increase # of calories/sugar in diet (125 kcal per bottle / 33 grams of sugar) o No nutrient fact box so don‟t know this ^ o False sense of security about health o May consume more than upper limits o Expensive o Mostly water soluble vitamins – Canadians not deficient in them CH8WATER &MINERALS Distribution of Water in Body  60% of body weight = water o 1/3 intracellular // 2/3 extracellular  Water move in and out of cell by: o Solutes concentration (dissolved substances) -eg protein, sodium potassium  Osmosis (water move from area of low concentration of substances to area of high concentration) – help equalize solute concentrations o Blood pressure = which forces water out of blood Water balance  when intake=output  Intake = water intake, food, metabolism  Lose = urine, feces, sweating, talking Water, Blood Volume & Blood Pressure  Low blood pressure can compromise nutrient delivery!!  Adequate water levels  maintain blood volume  maintain blood pressure 1. Thirst reflex  dryness in mouth, signal from brain to consume water 2. Kidney  water conservation, remove less 3. Vasoconstriction  narrow blood vessel, increase blood pressure  Water balance is regulated by 3 main hormones: o Antidiuretic Hormone (ADH) & Angiotensin II & Aldosterone Functions of Water 1. Solvent – dissolve substances (glucose, amino acids, minerals) 2. Chemical reaction of metabolism take place in water 3. Involved in Hydrolysis (break apart)/ dehydration reactions (join) 4. Part of blood, to deliver oxygen to cells, waste to lungs/kidney 5. Protection (lubrication, tears, cushioning, saliva) 6. Regulations of body temperature o blood carries heat from body core to surface of skin, heat is released to environment, water in sweat evaporates causing heat loss, then cools skin and blood, cooled blood returns to the body core Deficiency  Blood volume drops, impairs nutrient delivery, waste removal  Dehydration causes symptoms very rapidly, can also lead to deficiency in electrolytes o Early symptoms: thirst, headache, fatigue, loss of appetite, dry eyes/mouth, dark urine o Late symptoms: nausea, difficulty concentrating, confusion, disorientation, collapse o Water loss of +10-20% may result in death Toxicity  Hyponatremia = Too much water relative to sodium in body  sodium concentration drops o Water moves into tissues, leading to swelling o Swelling in brain can cause disorientation, convulsions o Early symptoms = nausea, muscle cramps, slurred speech, confusion Hot Topic: Is Bottled Water Better?  Benefits of Bottled  Benefits of Tap o Convenience o Less environmental footprint! o Taste o Cheaper o Cleaner than tap at remote area? o More strictly regulated o May contain necessary minerals o No BPA from plastic bottles Meeting Water Needs  Increase water needs: o Low calorie diets increase water needs = fat/protein breakdown to fuel, more waste needs to be excreted o High fiber diet o High salt diets  Caffeine, alcohol impair antidiuretic hormone (ADH) action  act as diuretic = increasing urge to urinate Minerals  Inorganic elements  Over 20 essential minerals found in plants/animals  Present naturally in foods or added from soil/food processing 1. Major minerals: need >100 mg/d 2. Trace minerals: need <100 mg/d o Need more of major minerals but doesn‟t make it more important!! Mineral Bioavailability  Depends on the source (ex. soil quality of where plants are grown), what else is eaten at the same time, the preparation and the individual  Easier to absorb from animal products vs. plant products o Because plants may contains substances that bind to minerals in GI tract and reduce absorption: 1. Oxalates (spinach)  In
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