Chapter 8 Notes
Chapter 8 Notes NTR 213-05
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This 24 page Class Notes was uploaded by Elizabeth Weathers on Saturday March 12, 2016. The Class Notes belongs to NTR 213-05 at University of North Carolina - Greensboro taught by Laurie H. Allen in Winter 2016. Since its upload, it has received 12 views. For similar materials see Introductory Nutrition in Environmental Science at University of North Carolina - Greensboro.
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Date Created: 03/12/16
Water 60% of body weight 2/3 intracellular (within cells), 1/3 extracellular Cell membranes are permeable to water Water crosses the membrane by osmosis to dilute dissolved solutes Blood pressure is generated by the heart to move water through blood vessels and into tissues Water Functions Acts as a solvent: solutes (for example: glucose, proteins, minerals) dissolve in water Participates in chemical reactions Water in the Body Water Balance Water is not stored Water in must equal water out In: consumption of water, fluids, foods and production during cellular respiration Out: excretion in urine and feces, evaporation from the skin and lungs, and sweating Increased Water Loss Stimulates Thirst Kidneys Regulate Body Water • Kidneys act as a filter • Water moves from the blood into kidney tubules • Blood cells and proteins are too large and remain in the blood • Needed substances are reabsorbed back into the blood • Un-needed substances are excreted in urine Antidiuretic Hormone (ADH) Increased ADH Water Decreased Blood Sodium Secretion Reabsorption Blood Sodium If more water is lost than taken in, then the concentration of solutes in the blood increases This stimulates thirst and secretion of ADH from the brain ADH stimulates the kidneys to reabsorb water (to keep the blood from becoming more concentrated Water Helps Cool the Body Dehydration Water loss is greater than water intake Reduces blood volume which reduces blood pressure Reduces the ability of the circulatory system to deliver oxygen and nutrients to muscles Reduces blood flow to the skin and sweat production limiting the body’s ability to cool itself Symptoms: Dry mouth, decreased urination, thirst, fatigue, headache, muscle cramps Severe dehydration: increased heart rate, decreased blood pressure, increased respiration, confusion Alcohol and Dehydration Alcohol blocks the secretion of ADH Kidneys do not reabsorb water they excrete it Oral Rehydration Solutions Water Intoxication (Overhydration) Water intake is greater than water loss Sodium in blood is diluted causing hyponatremia Hypo means low, Na is the chemical symbol for sodium, emia means in thesolutes causing tissue swelling, or edema blood Water moves by osmosis from the blood into the tissues to try to dilute the higher concentration of water Hyponatremia Meeting Water Needs • AI: men = 3.7 liters/day, women = 2.7 liters/day • Need increased intake with: Increased activity Increased temperature Decreased humidity Low-calorie diet High-salt diet High-fiber diet Alcohol intake Fluid Recommendations for Exercise Generous amounts of fluid in the 24 hours before an exercise session About 2 cups of fluid 4 hours before exercise 6–12 ounces of fluid every 15–20 minutes for the duration of the exercise After exercise, each pound of weight lost should be replaced with 16–24 oz (2 to 3 cups) For exercise lasting an hour or less, water is the only fluid needed For exercise lasting more than an hour, beverages containing carbohydrate (about 10 to 20 g of carbohydrate/cup) and electrolytes (around 150 milligrams of sodium in a cup) are recommended Fruit juices and soft drinks are not recommended unless diluted with an equal volume of water Minerals 20 needed by the body in small amounts Maintain structure and regulate chemical reactions and body processes Major mineral: need >100 milligrams/day sodium, potassium, chloride, calcium, phosphorus, magnesium, and sulfur Trace mineral: need <100 milligrams/day iron, copper, zinc, selenium, iodine, chromium, fluoride, manganese, molybdenum, and others Mineral Majo Trac Electrolyte Bone Sodiu Calciu Iro Chromiu Potassiu Phosphoru Coppe Fluorid Chlorid Magnesiu Zin Manganes Sulfu Seleniu Molybdemu Minerals from Food From plant and animal sources Affected by amount in soil Processing: Added (for example, during fortification) or germ)ed (for example, by cooking or removing skins, bran, or Absorption Bioavailability • Inhibited by substances in plants, other minerals, or amount in body Mineral Functions Contribute to body structures Regulate body processes Regulate water balance Regulate energy metabolism Affect growth and development through their role in the expression of certain genes Act as cofactors needed for enzyme activity Electrolytes Positively or negatively charged ion that conducts a current in solution Ions = charged atoms - charge: gained a negative electron + charge: lost a negative electron Fluid balance maintenance, nerve impulse conduction, cellular signaling Sodium + charge: lost a negative electron extracellular: outside of cells Potassium + charge: lost a negative electron intracellular: inside of cells Chloride – charge: gained a negative electron extracellular: outside of cells Electrolyte Imbalance Deficiency: Results in: acid–base imbalance, poor appetite, muscle cramps, confusion, apathy, constipation, irregular heartbeat, death Caused by: heavy/persistent sweating, chronic diarrhea or vomiting, kidney disorders, or medications Excess: Excess potassium from supplements can cause the heart to stop Excess sodium from dehydration/water loss: confusion, headache, and seizures Regulation of Blood Pressure Hypertension Blood pressure consistently at or above 140/90 mm mercury Caused by: increased contractions of the heart, increased blood volume, or decreased radius of blood vessels Results in: atherosclerosis, heart attacks, strokes, death Treated with: diet, exercise, and medication Risks: genetics, race, age, obesity, diet, activity Dietary Approaches for Stopping Hypertension Hypertension and Diet Electrolyte Recommendations Sodium: UL: 2300 mg/day = 1 tsp of salt Over 51 years old, African American or with medical conditions = 1500 mg/day Typical consumption = 3400 mg/day Potassium: DRI = 4700 mg/day DV = 3500 mg/day Typical consumption = 2000-3000 mg/day Sodium in Foods Bones Protein matrix: mostly collagen Hardened by minerals: mostly calcium, phosphorus, also magnesium, sodium, fluoride, other minerals Require: Protein and vitamin C to maintain collagen Calcium and other minerals to ensure solidity Vitamin D to maintain calcium and phosphorus levels Living tissue Support weight and participate in movement Constantly broken down and re-formed during bone remodeling Peak bone mass: maximum bone density attained life, usually in young adulthood Age related bone loss: bone loss that occurs in men and women as they advance in age (Amount of bone broken down starts to exceed amount that is formed) Osteoporosis Osteoporosis- bone disorder characterized by reduced bone mass and increased bone fragility Prevention Achieve a high peak bone mass Diet Weight bearing exercise No smoking Limit alcohol Treatment Supplements Ca and Vitamin D Weight bearing exercises Estrogen Biphosphonates NOTE: those with osteoporosis may be bent over because over time, the front edge of the spinal vertebrae collapses more than the back edge, so the spine bends forward; women also have a higher chance of getting Osteoporosis Calcium 99% in bones and teeth In body cells and fluids, needed for: Muscle contraction Neurotransmitter release Blood pressure regulation Cell communication Blood clotting Levels regulated by hormones: Homeostasis vital Too high: calcitonin “tones” it down Too low: PTH and calcitriol “try” to bring it up RDA: 19-50 years = 1000 mg/day; UL= 2500 mg/day Sources: dairy products, dark green vegetables, fish with bones, foods processed and fortified with calcium Deficiency: Osteoporosis Excess: caused by cancers, increased PTH, excessive calcium and/or vitamin D intake causing altered availability of iron, zinc, magnesium, phosphorus; constipation; loss of appetite, abnormal heartbeat, weight loss, fatigue, frequent urination, soft tissue calcification, kidney stones and damage Calcium Hormones Decreased blood PHT & Calcitriol Stimulates intestinal Increased Blood calcium secretion absorption, kidney Calcium reabsorption, & bone resorption Increased Blood Calcitonin secretion Inhibit bone Decreased Blood Calcium resorption Calcium Calcium Supplements Phosphorus Most found with calcium in bones and teeth In soft tissues, needed for: Phospholipid, DNA, RNA, and ATP structures Enzyme activity regulation Cellular acidity maintenance RDA: adults = 700 mg/day; UL= 4000 mg/day Sources: dairy products; meat; cereal; bran; eggs; nuts; fish; and food additives used in baked goods, cheese, processed meats, and soft drinks Deficiency: rare; due to chronic diarrhea or poor absorption due to overuse of aluminum- containing antacids; causes bone loss, weakness, loss of appetite Excess: high dietary phosphorus does not appear to be harmful for healthy adults, concern with sodas Magnesium 50-60% in bones In cells and fluids, needed for: Calcium regulation Blood pressure regulation ATP structure stabilization which is important for: Energy release from carbohydrate, fat, and protein Nerve and muscle functioning DNA, RNA, and protein synthesis RDA: men = 420 mg/day; women = 320 mg/day Sources: leafy greens, nuts, seeds, legumes, bananas, germ and bran of whole grains Deficiency: rare; causes osteoporosis, nausea, muscle weakness and cramping, irritability, mental derangement, blood pressure, heartbeat changes Excess: no effects from foods; drugs or supplements can cause nausea, vomiting, low blood pressure, and other cardiovascular changes Sulfur Part of: amino acids and proteins glutathione – needed for detoxification B vitamins thiamin and biotin Regulates acidity RDA: none Sources: part of dietary proteins and sulfur-containing vitamins, found in some food preservatives Deficiency: none known Iron Part of hemoglobin which transports oxygen to body cells and carries carbon dioxide away from them for elimination by the lungs Needed for other iron-containing proteins such as myoglobin, a muscle protein which increases oxygen available for contraction Essential for ATP production Heme iron in proteins is absorbed more than twice as efficiently as the nonheme iron in plant sources Iron Availability RDA: adults = 8 mg/day; UL = 45 mg/day Sources: red and organ meats, legumes, leafy greens, whole and enriched grains Deficiency: iron-deficiency anemia causing fatigue, weakness, headache, decreased work capacity, body temperature problems, behavior changes, increased infection, impaired development, lead poisoning Excess: intestinal lining damage, abnormal body acidity, shock, liver failure; iron overload from inherited hemochromatosis Iron Deficiency Iron Excess Iron can be harmful or fatal to children if taken in large doses Excess iron in vital organs, even in mild cases of iron overload, increases the risk for liver disease (cirrhosis, cancer), heart attack or heart failure, diabetes mellitus, osteoarthritis, osteoporosis, metabolic syndrome, hypothyroidism, hypogonadism, numerous symptoms and in some cases premature death Copper A copper-containing protein is needed for iron transport from intestinal cells Component of proteins and enzymes involved in: Connective tissue synthesis Lipid metabolism Heart muscle maintenance Immune and central nervous system functions RDA: adults = 900 micrograms/day; UL = 10 mg/day Sources: organ meats, seafood, nuts, seeds, whole-grain breads and cereals, chocolate Deficiency: iron-deficiency anemia, decreased collagen, high blood cholesterol, impaired growth, heart and nervous system degeneration, hair color and structure changes, increased infections, decreased antioxidants Excess: from supplements, copper containers, contaminated water, causing abdominal pain, vomiting, diarrhea Zinc Involved in the functioning enzymes involved in: Scavenging free radicals DNA and RNA synthesis Carbohydrate metabolism Acid–base balance Absorption of folate from food Storage and release of insulin Mobilization of vitamin A from liver Stabilization of cell membranes Influences hormonal regulation of cell division RDA: men = 11 mg/day; women = 8 mg/day Sources: meat, liver, eggs, dairy products, vegetables, legumes, seeds Deficiency: decreased growth, development and immunity; skin rashes; diarrhea, taste changes Excess: from supplements causing gastrointestinal irritation; vomiting; appetite loss; diarrhea, abdominal cramps; headaches; decreased immunity, HDL, copper and iron absorption Zinc & Gene Expression Selenium Incorporated into the structure of certain proteins: Glutathione peroxidase which decreases oxidative damage A protein needed to make thyroid hormones RDA: adults = 55 mg/day; UL = 400 mg/day Sources: seafood, kidney, liver, eggs, grains, nuts, seeds Deficiency: Keshan disease = heart disease in China; increased risk of cancer Iodine ¾ in the thyroid gland Component of thyroid hormones which regulate metabolic rate, growth, and development and promote protein synthesis RDA: adults = 150 mg/day; UL = 1100 mg/day Sources: seafood, iodinized salt, food contaminants and additives Deficiency: decreased thyroid hormones causing decreased metabolic rate, fatigue, weight gain; goiter (enlarged thyroid); during pregnancy causes spontaneous abortions, stillbirths, cretinism (brain damage) Excess: goiter Chromium Component of “glucose tolerance factor,” a small peptide required to maintain normal blood glucose levels RDA: ages 19–50: men = 35 micrograms/day; women = 25 micrograms/day Sources: liver, brewer’s yeast, nuts, whole grains Deficiency: rare in US Excess: little evidence Fluoride Incorporated into crystals in tooth enamel which protects against cavity-causing acids produced by bacteria In saliva, decreases bacterial acid production, inhibits dissolution of tooth enamel by acid, and increase enamel re-mineralization after acid exposure Incorporated into crystals in bone RDA: 0.05 mg/kg/day; UL = 0.1 mg/kg/day for infants and children less than 9 years old and 10 mg/day between 9 and 70 years Sources: in small amounts in almost all soil, water, plants, and animals; toothpaste; tea; marine fish with bones; fluoridated water Deficiency: tooth decay Excess: fluorosis causing black and brown stains and cracking and pitting of the teeth
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