nutrients=any substance in food that is used by the body to promote normal growth, maintenance, and...
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Nutrients=any substance in food that is used by the body to promote normal growth, maintenance, and repair.
Essential nutrients must be consumed in the diet.
There are six classes of nutrients.
OverviewClasses of nutrients: Carbohydrates, Lipids,
Proteins, Water, Vitamins, Minerals
RDA - recommended dietary amounts
Energy value of foods - kilocalorie - amount of heat energy to raise the temperature of 1 kilogram of water 1 degree Celsius
Composed of C, H, OProvide a major
source of fuel for the body
Basic unit is glucose Simple versus
Complex Energy yielding (4
kcal /gm)
CarbohydratesDivided into simple carbohydrates and
complex carbohydrates
Used in the process of ATP synthesis
Simple carbohydrates examples: soft drinks, candy, fruit, ice cream, pudding
Complex carbohydrates: bread, cereal, crackers, flour, pasta, nuts, rice, potatoes
RDA - 125-175 grams = 55-60% of total caloric intake
LipidsClasses: triglycerides, phospholipids, sterolsUsed in cell membrane synthesis, energy
production, vitamin storageAnimal sources: lard, meat, poultry, eggs,
milk, milk productsPlants sources: chocolate, corn soy,
cottonseed, olive oils, coconut, peanutsCholesterol sources: organ meats and egg
yolksRDA - 80-100 grams = 30% or less of total
caloric intake
Proteins20 amino acids 9 essential and 11 non-essentialUsed in synthesis of enzymes, antibodies,
hemoglobin, muscle, etc...Complete or incomplete depending if the source
has all amino acids needed by the bodyComplete protein sources: eggs, milk meat (fish,
poultry, pork, beef, lamb)Incomplete protein sources: legumes, nuts and
seeds, grains and cerealsRDA - 0.8g/kg of body weight = 10-15% of total
caloric intake
VitaminsTwo classes
Fat soluble - A, D, E, KWater soluble - C (ascorbic acid) and BB1: thiamine B2: riboflavin B3: nicotinamide (niacin)B5: pantothenic acidB6: pyridoxineBiotinB12 cyanocobalaminFolic acid
Uses Antioxidants (A,C&E), Hormone synthesis (D)Required for clotting proteins (K)Coenzymes (B vitamins)
RDA varies with each vitamin
MineralsSeven required (calcium, phosphorus,
potassium, sulfur, sodium. chloride, and magnesium)
Trace minerals needed (fluorine, cobalt, chromium, copper, iodine, iron, manganese, selenium, zinc)
Uses in bone formation, nerve transmission, cofactors of enzymes, protein synthesis, etc....
Metabolismsum of all the reactions occurring in the body at any
given time; a balance between catabolic and anabolic reactions
Catabolism – breakdown of complex organic compounds into simpler ones; reactions and are considered exergonic (gives off energy) and produces more energy than they consume
Anabolism – combining small organic compounds into larger ones; reactions are endergonic (requires energy) and consume more energy than they produce
Chemical reactions of living systems depend on efficiently transforming energy from one molecule to another. ATP (adenosine triphosphate) accomplishes this task.
ATP ADP + P + ENERGY
Composed of three pathways: Glycolysis, Krebs cycle, and Electron transport chain
ii. Glucose actively transported in GI tract then insulin-mediated facilitated diffusion in body cells
iii. Glycolysis Occurs in the cytosolOne six carbon glucose is split into two three
carbon pyruvate 2 ATPs are used but 4 are created2 nicotinamide adenine dinucleotide (NAD)
are hydrogenated
Krebs Cycle Pyruvate from glycolysis is converted into
Acetyl CoA in cytosol (NAD is hydrogenated and carbon dioxide is released)
Acetyl CoA is shuttled into the mitochondriaSeries of reactions takes placeOne ATP is created (per Acetyl CoA)2 carbon dioxides are released3 NADs are hydrogenatedOne flavin adenine dinucleotide (FAD) is
hydrogenated
Electron Transport Chain Occurs in the inner mitochondrial membraneElectrons and hydrogens are released from
NADs and FADsOxygen is the final electron acceptor -- if no
oxygen present lactic acid produced from pyruvate and krebs does not occur -- referred to as anaerobic carbohydrate metabolism
Hydrogen ions form a concentration gradient
A total of 36 ATP are produced from the complete breakdown of a glucose molecule.
Water and carbon dioxide are released as by products.
Chemical Equation for the entire reaction: C6H12O6 + 6O2 6H20 + 6CO2 + 36 ATP +
heat
Lipogenesis= triglyceride synthesis
Lipolysis=“fat splitting”
Metabolic rate=the body’s rate of energy output
Basal metabolic rate=the minimum energy expended in a fasting state (12 hours) to keep a resting, awake body alive in a warm, quiet environment.