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PROTEINS

PROTEINS. PROTEINS. Organic compounds Acid and amino group * nitrogen**** * side group. AMINO ACID STRUCTURE. AMINO ACID EXAMPLES. AMINO ACIDS. Basic building blocks of protein 20 amino acids 9 essential or indispensable-2 totally essential

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PROTEINS

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  1. PROTEINS

  2. PROTEINS • Organic compounds • Acid and amino group * nitrogen**** * side group

  3. AMINO ACID STRUCTURE

  4. AMINO ACID EXAMPLES

  5. AMINO ACIDS • Basic building blocks of protein • 20 amino acids • 9 essential or indispensable-2 totally essential deprived of essential AA body breaks down own proteins • 11 non-essential or dispensable body can make if proper amount of C, H, O, N • Conditionally essential • Linked by peptide bonds Dipeptide, tripeptide, polypeptide

  6. CONDENSATION

  7. AMINO ACIDS • Squencing: > specific order-exquisite and precise order > genetically determined > errorsickle cell disease > 6th amino acid valine is substituted for glutamine > RBC collapses, cannot carry oxygenillnesseven death

  8. AMINO ACIDS • Denaturation • Change may be irreversible • Heat, alcohol, acids, salts of heavy metals disrupt normal chain • Excess acidity or alkalinity damages body’s proteins

  9. DENATURATION

  10. DIGESTION/ABSORPTION • Mouth  breaks up food • Stomach  HCl  activates pepsinogen to pepsin • Pepsin  breaks down large polypeptides • Beginning of protein digestion

  11. DIGESTION – SMALL INTESTINE • Intestinal proteases and pancreatic proteases break down polypeptides  oligopeptides, tripeptides, dipeptides • Intestinal peptidases convert peptides to amino acids • Intestinal villi  amino acids portal vein to liver • Liver – monitors protein synthesis and frees amino acids to circulation • CATABOLISM – no storage • Bloodstream

  12. TRANSPORT OF AMINO ACIDS • Transport by diffusion • Villiportal veinliver • Liver monitors: 1. Protein synthesis 2. Free amino acids to circulation 3. Catabolism • Proteins are NOT stored- constant synthesis and catabolism Represents ~ 15-20% of REE

  13. FUNCTIONS OF PROTEIN • Growth, maintenance • Enzymes • Hormones • Antibodies • Fluid and electrolyte balance • Acid-base balance • Transportation • Blood clotting • Visual pigments • Energy

  14. GROWTH, MAINTENANCE • Growth – manufacture cells • Repair – collagen • Replacement • Protein turnover – synthesis and degradation

  15. ENZYMES - CATALYSTS

  16. ANTIBODIES • Antigens are invaders (bacterium, toxins, virus, allergens) • Body detects antigens  works to make antibodies • Antibody made with amino acids – pattern stored in DNA memory • Adequate protein aids immune system in making antibodies

  17. FLUID BALANCE • Proteinsamino acids • Amino acidstransported to cell –crosses cell wall • Inside cell build proteins • Large proteins do not cross over cell wall • Proteins made inside cell hold water inside • Proteins in bloodstream will draw fluid back into blood

  18. FLUID BALANCE • Blood pressure from pumping action of heart forces fluid into tissue spaces • Proteins in bloodstream draw water back into bloodstream as pressure declines • Without sufficient protein fluid remains in tissue spacesEDEMA

  19. EDEMA

  20. ACID-BASE BALANCE • Normal blood pH = 7.35-7.45 • Protein act as BUFFERS • Acidosis - acid (Low pH) = H+ ions Proteins accept H+ ions • Alkalosis - base ( pH) = H+ ions Proteins release H+ ions • Proteins can (+) or (-) H+ ions to maintain balance • If proteins not available or fullcoma or death

  21. TRANSPORT PROTEINS • Specific for compound or group of related compounds • Cell membranes-maintain equilibrium * in and out of cells * move into membrane but shuttle side to side • Carrier 1. Vitamins and minerals Fe – captured by protein (ferritin) in intestinal wall ferritin holds in bone marrow or other tissue until body needs Fe Protein (transferrin) carries Fe through bloodstream 2. Oxygen transport and use protein (hemoglobin) combines with Fe to carry O2 in fluids or myoglobin (protein) in muscle cells 3. Lipids- lipoproteins

  22. BLOOD CLOTTING • Tissue injuredFibrin made • Stringy protein fibers to plug leak • Also need Vit K and Calcium

  23. BLOOD CLOTTING - FIBRIN

  24. PROTEIN FOR ENERGY • Low priority use of protein • Energy needs must be meet • Increased need for water

  25. ENERGY • Deamination • Nitrogen stripped off ammonia  liver carbon skeleton + CO2 urea gluconeogenesis excreted by kidneys energy OR stored as fat

  26. PROTEIN EXCESS • NO storage – store as fat • May overload kidneys • May contribute to excess calorie intake • May contribute to calcium excretion • Use of animal proteins increase fat and cholesterol intake • Fat and CHO are protein sparing

  27. PROTEIN RECOMMENDATIONS • As % of total energy needs = 10-15% of calories • Grams/kilogram of body weight/day = 0.8-1.0 grams of protein/kilogram • RDA = 0.8 grams/kg of body weight • Protein needs affected by: illness, stress, age • Low protein diet  fatty liver, low skeletal mass

  28. DO ATHLETES NEED MORE PROTEIN???? • Casual aerobics 3 times/week 1 gram/kg more than enough • Strength building: to make new muscle Depends on LBM 1 gram/kg of body weight • Endurance (marathon, triathlon)-Muscle repair – muscle supplies 10-15% of energy during 1 hour run 2 grams/kg body weight • Begin training = 1-1.2 gms/kg • INGESTING LARGE QUANTITIES OF PROTEIN DOES NOT CAUSE MUSCLE TO INCREASE IN SIZE

  29. HEALTH EFFECTS OF PROTEIN • PEM – Protein-energy malnutrition • PCM – Protein-calorie malnutrition • Most widespread form of malnutrition today • Affects adults, but especially children • Acute – thin for height • Chronic – short for age • KWASHIORKOR • MARASMUS

  30. KWASHIORKOR AND MARASMUS

  31. KWASHIORKOR

  32. KWASHIORKOR • Adequate calories with low protein intake • Adipose tissue preserved • Skeletal muscle preserved or decreased • Relatively normal weight • Serum proteins decreased • Edema • Growth failure • Fatty liver • Apathy • Misery • Hair changes – pluckability, color strength, texture

  33. MARASMUS

  34. MARASMUS • Low Kcals and low protein intake • Low adipose tissue • Low skeletal mass • Significant weight loss • Serum proteins relatively normal • No edema • Ketosis • Immune system compromised • Decreased metabolism • Decreased body heat • Slows brain development-retardation • Growth retardation • Looks old and sick

  35. NUTRITION THERAPY • Fluid balance- electrolytes • Low fat milk – protein carriers • Add fat • Protein repletion

  36. MALNUTRITION IN HOSPITALIZED PATIENTS

  37. EVALUATE FOR PCM • Skeletal muscle Mid-arm muscle circumference Creatinine–height index: 24 hour urine collection – compare to standards • Serum proteins Albumin – WNL 3.5-5.0 gm/dl Prealbumin – WNL 20-50 mg/dl Total protein – WNL 6.0-8.4 gm/dl • Adipose tissue Circumferences Skin-fold measurements

  38. NITROGEN BALANCE

  39. NITROGEN BALANCE

  40. CALCULATIONS • N balance = protein intake/6.25 – [output (UUN) + 3] • Normal UUN = 6-17 gm/day • Protein intake = 60 gm/day UUN = 13 gm/day then: 60/6.25 = 9.6 9.6 – [13 + 3] 9.6 - 16 -6.4 gm N/day (catabolism)

  41. ANABOLISM • Protein intake = 75 gms/day UUN = 6 gm/day then: 75/6.25 = 12 12 – [6 + 3] 12 – 9 +3

  42. HIGHEST QUALITY PROTEIN?

  43. PROTEIN QUALITY • Chemical scoring • Biological value (BV) • Net protein utilization (NPU) • Protein efficiency ratio • Reference protein = egg = 100 (FAO of U.N.)

  44. PROTEIN QUALITY

  45. PROTEIN QUALITY • LIMITING AMINO ACID Essential amino acid – not enough for protein synthesis • COMPLETE PROTEINS All essential amino acids in amounts required by humans • COMPLEMENTARY PROTEINS Combining foods with limiting amino acids to make complete protein • DIGESTIBILITY

  46. COMPLETE/INCOMPLETE

  47. PROTEIN SOURCES

  48. COMPLEMENTATION

  49. VEGETARIAN DIETS • VEGANS – avoids all animal foods • SEMI – VEGETARIAN – no red meat • Lacto-ovo Vegetarian – Avoids meat but uses eggs and dairy products • Lacto-Vegetarian – Avoids meat and eggs but uses dairy products • Vegetarians may need more total protein in diet: 45 grams of high quality protein vs 65 grams of lower quality protein

  50. BENEFITS TO VEGETARIANISM • Lower Calories IBW, Lower BP • Higher fiber diet decreased risk of Cancer •  increased digestive function • Lower Blood Cholesterol leveldecrease in cardiovascular disease • Decreased Bone Lossless calcium loss

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