Exam 3 - Nutrition and Metabolism Flashcards
(40 cards)
Nutrition
The process by which the body obtains and uses certain components of food. The process includes:
1) Digestion
2) Absorption
3) Transportation
4) Cell metabolism
Nutrients
Substances taken into the body that are used by the cells of the body to produce energy, to provide building blocks for new molecules, and to function in other chemical reactions. Divided into six major classes:
1) Carbohydrates
2) Lipids
3) Proteins
4) Vitamins
5) Minerals
6) Water
Essential nutrients
Indispensable nutrients
Substances that must be ingested because the body cannot manufacture them at all or cannot manufacture adequate amounts of them. Include:
1) Certain amino acids and fatty acids
2) Most vitamins
3) Minerals
4) Water
5) A few carbohydrates
Kilocarloies
1000 calories
Used to express the larger amounts of energy supplied by foods and released through metabolism
Amount of energy (heat) necessary to raise the temperature of 1000g of water 1 degree C
MyPlate
A food icon to replace the former food icon, myPyramid
MyPlate is a simple visual reminder of how to build a healthful meal
Shows a plate and glass with portions representing foods from fruits, vegetables, grains, proteins, and dairy food groups
Dietary sources of carbohydrates
Most come from plants, with the exception of lactose. Complex carbohydrates: Whole grains, legumes, vegetables, fruits
Simple carbohydrates: Table sugar, honey, candy, fruit juices
Carbohydrate uses in body
1) Energy production: Carbohydrates are broken down into glucose, which fuels all body cells, especially the brain, muscles, and red blood cells
2) Glycogen storage:
Disaccharides and polysaccharides are converted to glucose, or stored as glycogen, which is a short-term energy-storage molecule that the body can store in liver and muscles in limited amounts
3) Sparing protein: Carbohydrates prevent body from breaking down muscle protein for energy
4) Digestive health: Dietary fiber, a type of carbohydrate, promotes healthy digestion and helps regulate sugar
Daily recommended amounts of carbohydrates in diet
General recommendations: 45-65% of daily calories
Fiber recommendations: 25g/day for women and 38g/day for men
Types of carbohydrates
1) Monosaccharides: Glucose, fructose, galactose
2) Disaccharides: Sucrose, maltose, lactose
3) Polysaccharides (complex): Starch, glycogen, cellulose; Cellulose is indigestible
Disaccharides and polysaccharides are converted to glucose
Types of lipids and their dietary sources
1) Triglycerides: Used for energy or stored; 95%; Includes saturated fats, like meat fats, whole milk, cheese, and eggs, and unsaturated fats, like olive and peanut oil
2) Cholesterol: Steroid found in liver, egg yolks, but not found in plants
3) Phospholipids: Major components of plasma membranes
4) Linoleic acids: Essential fatty acids. Found in seeds, nuts, legumes, grains, and green leaves
Uses of lipids in the body
Triglycerides: Produce ATP. Excess stored in adipose tissue or liver
Cholesterol: Ingested or made in body. Used in plasma membranes, bile salts, and steroids
Eicosanoids: Derived from fatty acids. Used for inflammation, blood clotting, tissue repair, smooth muscle contraction
Phospholipids: Used in plasma membrane, myeline sheath, bile
Dietary sources of protein
Chains of amino acids. Two types:
1) Essential: Must be obtained in a diet
2) Nonessential: Body can synthesize
Complete proteins: Contain all necessary amino acids, like meat, fish, poultry, milk, cheese, and eggs
Uses of protein in the body
1) Protection: Antibodies
2) Regulation: Enzymes and hormones
3) Structure: Collagen
4) Muscle contraction: Actin and myosin
5) Transportation: Hemoglobin and ion channels
Metabolism
Total of all the chemical reactions that occur in the body. Consists of catabolism and anabolism
Catabolism
Includes the energy-releasing process by which large molecules are broken down into smaller molecules
Hormones: Glucagon, epinephrine, cortisol
Anabolism
Includes the energy-requiring process by which small molecules are joined to form larger molecules
Hormones: Testosterone, growth hormone, IGF-1, insulin
Glycolysis
Beginning of carbohydrate metabolism
Series of chemical reactions that result in the breakdown of glucose into two pyruvate molecules
Four phases:
1) Input of ATP: Two ATP used in phosphorylation, where phosphate group is transferred from ATP to glucose
2) Sugar cleavage
3) NADH production:
4) ATP and pyruvate production: One glucose produces four ATP molecules, two NADH, and two pyruvate molecules. Final yield of each glucose molecules is two ATP, two NADH, and two pyruvate molecules
Citric acid cycle
Two acetyl-CoA molecules enter the citric acid cycle, which produces four CO2, six NADH, two FADH2, and two ATP
Electron-Transport chain
Uses NADH and FADH2 to produce 28 ATP. Process requires O2, which combines with H+ to form H2O
Aerobic respiration process
Glycolysis
Citric acid
Electron-transport chain
Each glucose molecule produces a net gain of 32 ATP molecules: 2 from glycolysis, 2 from citric acid cycle, and 28 from electron-transport chain
Lipid metabolism
Triglycerides are broken down into glycerol and fatty acids. Glycerol enters glycolysis to produce ATP. Fatty acids are broken down by beta-oxidation into acetyl-CoA, which enters the citric acid cycle to produce ATP and electron carriers. Acetyl-CoA can also be used to produce ketone bodies. Glucose is converted to glycerol, and amino acids are converted to acetyl-CoA molecules. Acetyl-CoA molecules can combine to form fatty acids. Glycerol and fatty acids join to form triglycerides
Absorptive metabolic state
Absorptive: Period immediately after a meal, when nutrients are being absorbed through the intestinal wall into the circulatory and lymphatic systems. Usually lasts about 4 hours after each meal. Cells use most of the glucose that enters the body for energy they require. Remainder is converted into glycogen or lipids. Most absorbed lipids are deposited in adipose tissue. Many absorbed amino acids are used by cells for protein synthesis or energy. Secretion stimulated by increased blood glucose, increased blood amino acids, and the hormones, gastrin, CCK, and secretin. Food in gut
Minerals
Inorganic and necessary for normal metabolic functions
Functions: Establish resting membrane potentials, generate action potentials, add strength to bones and teeth, buffers, involved in osmotic balance, are components of coenzymes, vitamins, and hemoglobin
Obtained from animal and plant sources
Vitamins
Provitamins: Organic molecules in minute quantities of food. Can be conerted to functioning vitamins
Classifications:
1) Lipid-soluble: A, D, E, K. Can be stored in fatty tissues
2) Water-soluble: B, C, and all others. Remain short time then are excreted
Function: Coenzymes combine with enzymes and make the enzyme functional
