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Nutrition, Metabolism, and Body Temp Regulation


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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?
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?
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?
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?
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?
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?
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.

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