Nutrition, Metabolism, and Body Temp Regulation
Terms
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- What are essential nutrients?
- Nutrients that cannot be synthesized by body cells and must be ingested in diet.
- How are carbohydrates usually obtained?
- From plant products.
- How are monosaccharides primarily used?
- As cellular fuel.
- What is ATP?
- Chemical energy form used by cells.
- What are the primary sources of saturated fats?
- Animal products
- What are the primary sources of unsaturated fats?
- Plant products
- What ar the primary sources of cholesterol?
- Egg yolks, meats, milk products
- What are the functions of neutral fats?
- To reserve energy, cushion body organs, and insulate body.
- How is cholesterol used?
- In plasma membranes and is the structural basis of vitamin D, steroid hormones, and bile salts.
- What is the recommended percentage for caloric intake of fats?
- 30 percent or less.
- What is the recommended intake of cholesterol?
- 250 mg. or less.
- What requirements must be met for protein synthesis to occur?
- All essential amino acids must be present and sufficient carbohydrat (or fat) calories available to produce ATP.
- What is the recommended caloric intake range?
- 1500 - 2800 calories daily.
- What are the 6 categories of the food pyramid from top to bottom?
- Fats, Dairy, Proteins, Veggie, Fruits, Carbohydrates
- What is Glucose?
- Monosaccharide that is a major body fuel and is readily used to make ATP.
- Which vitamins are made in the body?
- Vitamins B, D, K.
- Which vitamins are fat soluble?
- Vitamins A, D, E and K
- Which vitamin is incapable of being stored in toxic amounts?
- Vitamin K.
- What are some minerals that must be present in the body in trace amounts?
- Calcium, Chloride, Magnesium, Phosphorus, Potassium, Sulfur, Sodium.
- What are some uses of minerals in the body?
- Mineralize bone, exist as ions in body fluids where they play various roles in cell processes and metabolism.
- What are the richest sources of minerals?
- Animal products, vegetables and legumes.
- What are the 2 categories of metabolic processes?
- Anabolic or catabolic
- What is cellular respiration?
- Group of catabolic reactions where food fuels are broken down in cells and some energy released is captured to form ATP.
- When is energy released?
- When organic compounds are oxidized.
- How is glucose oxidized to carbon dioxide and water?
- Glycolysis, Krebs cycle, and electron transport chain.
- What happens when cellular ATP reserves are high?
- Glucose catabolism is inhibited and glucose is converted to glycogen (glycogenesis) or to fat (lipogenesis).
- What is gluconeogenesis?
- Formation of glucose from noncarbonhydrate (fat or protein) molecules. Occurs in liver when blood glucose levels begin to fall.
- What is lipolysis?
- Breakdown of fats to fatty acids and glycerol.
- What happens when the body uses excessive amounts of fats?
- Liver converts acetyl CoA to ketone bodies and releases them to blood.
- All cells use two ingredients to build their plasma membranes. Name them.
- Phospholipids, cholesterol.
- What conversion does amino acids undergo to be oxidized for energy?
- Amino acids are converted to keto acids that can enter the Krebs cycle.
- What are the body's most important building blocks?
- Amino acids.
- How is urea formed?
- Amine groups removed during deamination combine with carbon dioxide by the liver to form urea.
- What is the postabsorptive state?
- Period when bloodborne fuels are provided by breakdown of energy reserves.
- How are events of the postabsorptive state controlled?
- By glucagon and the sympathetic nervous system, which mobilize glycogen and fat reserves and trigger gluco-neogenesis.
- What are some functions of the liver?
- It helps maintain blood energy sources, metabolizes hormones, and detoxifies drugs and other substances.
- How does obesity occur?
- When excess amounts of energy are stored, 20% or more above norm.
- What is the metabolic rate?
- Body's rate of energy output.
- What is the basal metabolic rate (BMR)?
- Energy the body needs to perform only essential activities (breathing, rest).
- What factors influence metabolic rate?
- Age, sex, size, body surface area, thyroxine levels, dynamic action of foods, muscular activity.
- When the body is at rest, what organs generate body heat?
- Liver, heart, brain, kidneys, endocrine organs.
- What parts of the body has the highest temperature?
- Body core (organs with skull and ventral body cavity).
- What are some heat-exchange mechanisms?
- Radiation, conduction, convection and evaporation.
- What organ is the body's thermostat?
- Hypothalamus.
- What are some heat-promoting mechanisms?
- Vasoconstriction of cutaneous blood vessels; increased metabolic rate; shivering; enhanced thyroxine release; behavioral modifications.
- What are the most abundant dietary lipids?
- Neutral fats (triglycerides aka triacyglycerols).
- What is a nutrient?
- Substance in food that is used by body to promote normal growth, maintenance, and repair.
- What are the six categories of nutrients?
- Carbohydrates, lipids, proteins, vitamins, minerals, water.
- What is the current recommendation of carbohydrate consumption per day?
- 125 - 175 grams with emphasis on complex carbohydrates.
- What are the most common dietary lipids?
- Neutral fats, triglycerides
- Why are dietary fats essential?
- Major source of fuel for hepatocytes and skeletal muscle, absorption of fat-soluble vitamins, components of myelin sheaths and cellular membranes of body.
- Define dehydrogenases.
- Enzymes that catalyze redox reactions where hydrogen atoms are removed.
- What factors determine protein needs of a person?
- Age, size, metabolic rate, current state of nitrogen balance.
- What are vitamins?
- Potent organic compounds needed in small amounts for growth and good health.
- Which vitamins are water-soluble?
- Vitamins B complex and C.
- What quality does Vitamins A, C and E possess?
- They are antioxidants that disarm tissue-damaging free radicals.
- What is anabolism?
- Reactions where larger molecules or structures built from smaller ones.
- What is catabolism?
- Processes that break down complex structures to simpler ones.
- What happens in oxidation-reduction reactions?
- One substance is oxidized and loses energy by losing electrons, while another substance is reduced and gains energy and electrons transferred from oxidized substance.
- What happens during substrate-level phosphorylation?
- High-energy phosphate groups transfer directly from phosphorylated substrates to ADP.
- What is glycogenesis?
- Formation of glycogen, the animal storage form of glucose, that occurs when excess glucose is ingested.
- What is glycogenolysis?
- Breakdown of glycogen into individual glucose molecules that occurs when blood sugar levels drop.
- What is lipogenesis?
- Reformation of triglycerides from unused glycerol and fatty acid chains for storage in body.
- What is transamination?
- Process of transferring an amine group to alpha-ketoglutaric acid to make glutamic acid.
- Where does oxidative deamination occur?
- In liver.
- When does the absorptive state take place?
- During and shortly after eating when nutrients are moving into the blood from the GI tract.
- What happens to absorbed monosaccharides?
- Delivery to liver and converted into glucose. Used by body cells, stored as glycogen, or converted into stored fats.
- What happens to triglycerides?
- Used for anabolic purposes or stored in adipose (fat) tissue.
- What are sources of blood glucose?
- Glycogen in liver, skeletal muscle cells, adipose tissues, cellular proteins.
- What is glucose sparing?
- Increased use of noncarbohydrate fuel molecules for energy to save glucose during times of fasting.
- What directs all events of the absorptive state?
- Insulin.
- What directs all events of the postabsorptive state?
- Sympathetic nervous system and several hormones.
- Where is cholesterol made?
- In liver and other body cells.
- How is cholesterol removed from the body?
- Through bile salts in feces.
- How is cholesterol transported in the body?
- It binds to small lip-protein complexes called lipoproteins.
- What is energy intake?
- Energy liberated during food oxidation.
- What is energy output?
- Includes energy lost as heat, used to do work, energy stored as fat or glycogen.
- What factors control eating?
- Neural signals from digestive system, bloodborne signals related to body energy stores, hormones, body temp, psychological factors.
- What is the total metabolic rate (TMR)?
- Rate of kilocalorie consumption needed to fuel all ongoing activities both involuntary and voluntary.
- What is conduction?
- Transfer of heat from a warmer object to a cooler one when the two are in direct contact with each other.
- How does convection occur?
- When warm air surrounding body expands and rises and is replaced by cooler air molecules.
- How are heat-promoting mechanisms triggered?
- When external temperature is low; blood temperature falls, heat-romoting center is activated.
- What is the purpose of heat-loss mechanisms?
- To protect body from excessively high temps.
- Why are proteins needed?
- For muscle and bone growth.
- What qualities does adipose tissue provide?
- Protective cushion, insulation, energy fuel source.
- What is the role of prostaglandins?
- Smooth muscle contraction, control of bp and inflammation.
- What functions does cholesterol serve?
- Stabilizing component of plasma membranes; precursor from which bile salts, steroid hormones and other essential molecules are formed.
- What is the percentage of fat in the typical American diet?
- 40%
- What is the recommended intake of saturated fats?
- 10% or less.
- What is the recommended cholesterol intake per day?
- 200 mg (1 egg)
- What foods are considered complete proteins?
- Eggs, milk, milk products, meat.
- What foods are considered incomplete proteins?
- Beans, Nuts, seeds, grains, cereals, veggies.
- What is the all or none rule?
- All amino acids needed to make a particular protein must be present in a cell at the same time and in sufficient amounts.
- What must occur in order for optimal protein synthesis to take place?
- Diet must supply sufficient carbohydrate/fat calories for ATP production.
- When is the body in positive nitrogen balance?
- When amount of protein incorporated into tissue is greater than amount being broken down and used for energy.
- When is the body in negative nitrogen balance?
- When protein breakdown for energy exceeds protein amount being incorporated into tissues.
- What do anabolic hormones do?
- Accelerate protein synthesis and growth.
- What does phosphorylation do?
- Primes molecule to change in a way that increases its activity, produces motion, or does work.
- Describe Stage 1 of Energy-containing nutrient processing.
- Digestion in GI tract. Absored nutrients transported in blood to tissue cells.
- Describe Stage 2 of Energy-containing nutrient processing.
- In cell cytoplasm, nutrients are either built into lipids, proteins glycogen by anabolic pathways or broken down by catabolic pathways to pyruvic acid and acetyl CoA.
- Describe Stage 3 of Energy-containing nutrient processing.
- Almost all catabolic, occurs in mitochondria. Requires oxygen and completes food breakdown, producing CO and water and harvesting large amounts of ATP.
- What are 2 important coenzymes of oxidative pathways?
- NAD+ (niacin), FAD (riboflavin).
- How do cells capture energy liberated during cellular respiration to make ATP?
- Substrate-level phosphorylation and oxidative phosphorlation.
- All food carbohydrates eventually become?
- Glucose.
- Which cells are capable of reversing phosphorylation reactions?
- Intestinal mucosa, kidney tubule, liver cells,
- What are the 3 major phases of the glycolytic pathway?
- Sugar activation and clevage, Oxidation and ATP formation.
- What are the final products of glycolysis?
- 2 molecules of pyruvic acid and two molecules of reduced NAD+, with net gain of 2 ATP molecules.
- What is the Krebs Cycle?
- Next stage of glucose oxidation. Occurs in mitochondrial matrix and fueled by pyruvic acid produced during glycolysis.
- Krebs Cycle is aka?
- Citric acid cycle.
- What are the products of the Krebs Cycle?
- 2 CO2 molecules, 4 molecules of reduced coenzymes.
- What are purposes of the Krebs Cycle?
- Final common pathway for oxidation of food fuels; source of building materials for anabolic reactions.
- During cellular respiration, what is the energy flow?
- Glucose - NADH + H+ - electron transport chain - proton motive force - ATP.
- What is the percentage of stored fat in the body?
- 80 - 85%
- What is the energy source of skeletal muscles that have depleted their energy supply?
- Liver glycogen.
- Define beta oxidation.
- Initial phase of fatty acid oxidation, occuring in mitochondria.
- When does lipogenesis take place?
- When cellular ATP and glucose levels are high.
- What is ketogenesis?
- The conversion of acetyl CoA molecules to ketones by the liver.
- What is metabolic acidosis?
- Body's buffer systems cannot tie up ketones fast enough, and blood pH drops to dangerously low levels.
- What must happen before amino acids can be oxidized for energy?
- They must be deaminated (amine group (NH2) removed).
- Which cells use triglycerides as their primary energy source?
- Adipose, skeletal muscle and liver cells.
- Insulin is classified as what type of hormone?
- Hypoglycemic.
- How does Diabetes Mellitus occur?
- Inadequate insulin production or abnormal insulin receptors.
- What is the primary goal of the postabsorptive state?
- Between meals when blood glucose levels are dropping, to maintain blood glucose levels within homeostatic range (80-100 mg).
- How are triglycerides and cholesterol transported?
- By small lipid protein complexes called lipoproteins.
- What is the role of LDL?
- Transport cholesterol to peripheral tissues, making it available to tissue cells for use later.
- What is the major function of HDLs?
- Transport excess cholesterol from peripheral tissues to the liver.
- What is the consensus on HDLs?
- Good because transported cholesterol is destined for degradation. (Level between 35 - 60 okay)
- What is the consensus on LDLs?
- Bad because when excessive (160 and up), potentially lethal cholesterol deposits are laid down in artery walls.
- What effect does saturated fatty acids have on blood cholesterol levels?
- They stimulate liver synthesis of cholesterol and inhibit its excretion from body.
- What effect does unsaturated fatty acids have on blood cholesterol levels?
- They enhance excretion of cholesterol and its catabolism to bile salts, thereby reducing total cholesterol levels.
- What effect does hydrogenation have on fatty acids?
- It changes fatty acids in the oils to trans fatty acids, which causes serum changes worse than those caused by saturated fats.
- What effect does omega-3 fatty acids have on fats and cholesterol?
- It lowers the proportions of both.
- Between "apples" and "pears", who has the best cholesterol and fat levels?
- Pears.
- What does a cell do when it needs cholesterol?
- It makes receptor proteins for LDL and inserts them in its plasma membrane.
- What is Body Mass Index?
- Official medical measure of obesity and body fatness.
- What are orexins?
- Peptide that enhances appetite.
- What is Neuropeptide Y?
- Peptide in hypothalamus that causes carbohydrate craving (most potent appetite stimulant known).
- What is Galanin?
- Peptide causing craving for fats.
- What does GLP-1 and serotonin do?
- Make us feel full and satisfied (receptors in hypothalamus).
- What are some other hormonal controls (besides Insulin) that affect appetite?
-
Epinephrine (released during fasting) triggers hunger.
Cholecystokinin depresses hunger. - What is Leptin?
- Satiety signal secreted by fat tissue in response to increase in body fat mass.
- What is throxine?
- "Metabolic hormone" that directs body cells to increase O2 consumption, by accelerating use of ATP to operate sodium-potassium pump.
- What is Total Metabolic Rate (TMR)?
- Rate of kilocalorie consumption needed to fule all ongoing activities involuntary and voluntary.
- What is the normal body temperature average and range?
-
36.2C (98.2F) average
35.6 - 37.8C (96-100F) range - Where is the best indicator of core temperature on the body?
- The rectum.
- What is insensible water loss?
- Basal level of body heat loss due to continuous evaporation of water from lungs, oral mucosa and skin.
- What is insensible heat loss?
- The heat loss that accompanies insensible water loss.
- What is the main integrating center for thermoregulation?
- The Hypothalamus.
- Define Chemical (nonshivering) thermogenesis.
- The release of norepinephrine by sympathetic nerve fibers in response to cold that elevates metabolic rate.
- Define Shivering.
- Brain centers controlling muscle tone activate when cold; when muscle tone reaches sufficient levels to alternately stimulate stretch receptors in muscles, muscles begin involuntary shuddering contractions.
- Define Phenylketonuria (PKU).
- Tissue cells are unable to use amino acid phenylalanine, that is present in all protein foods. Causes brain damage and retardation.
- Define Galactosemia.
- Lack of liver enzymes needed to transform galactose to glucose. Leads to mental deficits.
- Define Kwashiorkor.
- Severe protein deficiency in children, resulting in mental retardation and failure to grow.