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Nutrition, Metabolism & Body Temperature Regulation

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what is ATP   the chemical energy form used by cells to drive their many activities  
the energy value of foods is measured in units called   kilocalories  
one kilocalorie is the   amount of heat energy needed to raise the temperature of 1 kilogram of water 1C & is the unit conscientiously counted by dieters  
major nutrients are   carbohydrates, lipids & proteins  
what is a nutrient   a substance in food that is used by the body to promote normal growth, maintenance & repair  
essential nutrients   cannot be made by such interconversions & must be provided by the diet  
what is cellulose   a polysaccharide plentiful in most vegetables, not digested by humans but provides roughage or fiber  
glucose   is a monosaccharide carbohydrate molecule; major body fuel & is readily used to make ATP  
carbohydrate digestion yields   gructose & galactose (converted to glucose by the liver before they enter the general circulation)  
when glucose is present in excess of what the body needs for ATP synthesis, it is   converted to glycogen or fat & stored for later use  
what is the current recommendation of charbohydrates daily   125 to 175 grams  
what is the term used to describe highly refined carbohydrates such as candy & soft drinks   empty calories  
what are the major sources of unsaturated fats   seeds, nuts & most vegetable oils  
major sources of cholesterol are   egg yolk, meats (organ meats like liver) & milk products  
the liver cannot synthesize   linoleic acid, a fatty acid component of lecithin  
an example of an essential fatty acid is   linoleic acid  
what do fatty deposits in adipose tissue provide?   (1) protective cushion around body organs such as kidneys & eyeballs (2) insulating layer beneath the skin (3) easy-to-store concentrated source of energy fuel  
prostaglandins   regulatory molecules; plays a role in smooth muscle contraction, control of blood pressure & inflammation  
how are prostaglandins formed   from linoleic acid via arachidonic acid  
why is cholesterol important   it is used as a stabilizing component of plasma membranes & is the precursor from which bile salts, steroid hormones & other essential functional molecules are formed  
daily cholestrol intake should be   no more than 200 mg (the amount of one egg yolk)  
name two drawbacks to most fat substitutes   (1) don't stand up to the inense heat needed to fry foods (2) dont taste nearly as good as the "real thing"; the ones that are not absorbed tend to cause flatus (gas) & may interfere w. absorptionof fat-soluble drugs & vitamins  
what are complete proteins   they meet all the body's amino acid requirements for tissue maintenace & growth  
what is the importance of proteins in the body?   keratin of skin, collagen & elastin of connective tissues & muscle proteins  
what is the all or none rule   all a.a. needed to bake a particular protein must be present in a cell @ the same time; if one is missing protein will not be made  
why does this happen   b.c. essential amino acids cannot be stored, therefore those not used immediately to build proteins are oxidized for energy or converted to carbohydrates or fats  
what happens if the diet does not supply sufficient carbohydrate or fat calories for ATP production   dietary & tissue proteins are used for energy  
what is the percentage of nitrogen content of protein   16%  
when is the body in nitrogen balance   when the amount of nitrogen ingested in proteins equals the amount excreted in urine & feces  
explain when the body is in positive nitrogen balance   when protein synthesis exceeds protein breakdown & loss (normal in growing children & pregnant women); also occurs when tissues are being rebuilt or repaired following illness or injury  
what does a positive nitrogen balance always indicate   that the amount of protein being incorporated into tissue is greater than the amount being brokendown & used for energy  
a negative nitrogen balance is   protein breakdown exceeds the use of protein for building structural or functional molecules  
when would negative nitrogen balance occur   during physcal & emotional stress (infection, injury, burns, depression or anxiety) during starvation  
what are anabolic hormones   they accelerate protein synthesis & growth  
give an example of how an anabolic hormone works   pituitary growth hormone stimulates tissue growth during childhood & conserves protein in adults  
give another example   the adrenal glucocorticoids released during stress, enhance protein breakdown & conversion of amino acids to glucose  
most vitamins function as ____   coenzymes; that is they act w. an enzyme to accomplish a particular chemical task  
why are vitamins crucial   they help the body to use those nutrients that do; w.o. them all carbs, proteins & fats would be useless  
where is vitamin D made   in the skin  
what vitamins are syntehsized by intestinal bacteria   B & K  
how are vitamins classifyied   as fat soluble or water soluble  
what are examples of water souble vitamins   B-complex vitamins & vitamin C  
what are water souble vitamins   they are absorbed along w. water from the gastrointestinal tract (w. exception to B12 which must bind to gastic intrinsic factor to be absorbed)  
water-souble vitamins can easily be stored & if theyre not used can be   excreted in urine  
what are the fat-soluble vitamins   A, D, E, K  
what do fat-soluble vitamins   they bind to ingested lipids & are absorbed along w. their digestion products  
what can interfer w. fat-soluble vitamins   anything that interferes w. fat absorption  
what are antioxidants   they disarm tissue-damaging free radicals & have anticancer effects  
what are examples of antioxidants?   vitamins A, C, & E  
list the 7 minerals needed   calcium, phosphorus, potassium, sulfur, sodium, chloride & magnesium  
what is the purpose of calcium, phosphorus & magnesium salts   they harden the teeth & strengthen the skeleton  
most minerals   are inonized in body fluids or bound to organic compounds to form molecules such as phospholipids, hormones, enzymes & other functional proteins  
give an example of how this works   iron is essential to the oxygen-binding heme of hemoglobin; sodium & chloride ions are major electrolytes n blood that help maintain (1) normal osmolarity & water balance of body fluids (2) responsiveness of neurons & muscle cells to stimuli  
anabolism   synthetic; includes reactions in which larger molecules or structures are built from smaller ones; ex. bonding of amino acids to make proteins & of proteins & lipids to form cell membranes  
catabolism   process that break down complex structures to simpler ones; ex. hydrolysis of foods in the digestive tract  
cellular respiration   primary function is to generate ATP, which traps some of the chemical energy of the original food molecules in its own high-energy bons; group of reactions which food fuels (particularly glucose) are broken down within cells & some of the energy released  
phosphorylated   when enzymes shift their high-energy phosphate groups to other molecules  
what does phosphorylation do   it energizes, or primes, the molecule to change in a way that increases its activity, produces motion or does work; ex. many regulatory enzymes that catalyze key steps inmetabolic pathways are activated by phosphorylation  
oxidation reactions   the energy-yielding (ATP-yeilding) reactions within cells;  
when does oxidation occurs   via the gain of oxygen or the loss of hydrogen  
when on substance loses electrons it is   oxidized  
when one substance gains electrons it is   reduced  
redox reactions means that   "oxidized" substances lose energy & "reduced" substances gain energy as energy-rich electrons are transferred from the first to the second  
dehydrogenase   when enzymes that catalyze oxidation-reduction reactions by removing hydrogen  
oxidases   those catalyzing the transfer of oxygen  
coenzymes   act as reversible hydrogen (or electron) acceptors, becoming reduced each time a substrate is oxidized  
NAD+   nicotinamide adenine dinucleotide; based on niacin  
FAD   flavin adenine dinucleotide; derived from riboflavin  
substrate-level phosphorylation   occurs when high-energy phosphate groups are transferred directly from phosphorylated substrates (metabolic intermediates) to ATP  
the enzymes catalyzing substrat-level phosphorylation are located in both the   cytoplasm & in the watery environment inside the mitochondria (mitochondrial matrix)  
oxidative phosphorylation   releases most of the energy that is eventually captured in ATP bonds during cellular respiration  
how is the oxidative phosphorylation process carried out?   by electron transport proteins forming part of the cristae membranes in the mitochondria  
chemiosmotic process   couples the movement of substannces across membranes to chemical reations; some of the energy released during the oxidation of food fuels is used to pump hydrogen ios or protos across the inner mitochondrial membrane into the intermembrane space; creating  
ATP synthase   a membrane channel protei that allows protons to flow back across the membrane  
the catabolic & anabolic pathways for carbohydrates all begin with   glucose-6-phosphate  
glycolysis   "sugar spliting"; 10 chemical steps;  
glycolysis results in   two pyruvic acid molecules; yielding a net gain of 2 ATP per glucose molecule; 2 moecules of reduced NAD+  
where does glycolysis occur   in the cytosol of cells, where its steps are catalyzed by specific soluble enzymes  
what type of process is glycolysis   an anaerobic process; meaning it does not use oxygen & occurs whether or not oxygen is present  
In step 1 of glycolysis ATP is   consumed-an energy investment that will be repaid with dividends later in glycolysis  
are the steps in glycolysis reversible   all except the 1st one  
list the 3 main stages in glycolysis listed in the book   1. sugar activation 2. sugar cleavage 3. oxidation & ATP formation  
what's going on during the 2nd stage   fructose-1, 6-diphosphate is split into 3-carbon fragemnts that exist (reversibly) as one of 2 isomers; glyceraldehyde 3-phosphate or dihydroxyacetone phosphate  
lactic acid is the production yeild of   two adition hydrogen atoms to pyruvic acid  
when glucose is completely oxidized how many ATP/glucose molecues are harvested   36  
where does the Krebs cycle occur?   in aqueous mitochonrial matrix & is fueled largely by pyruvic acid produced during glycolysis & by fatty acids resultig from fat breakdown  
what is the first order of bussiness during the Krebs cycle after pyruvic acid enters the mjitochondria   to convert it to acetyl CoA  
1) decarboxylation   when one of the pyruvic acid's carbons is removed & released as carbon dioxide gas (a waste product of metabolism) CO2 diffuses out of the cells into the blood to be expelled by the lungs  
2)oxidation   the removal of hydrogen atoms; the removed hydrogens are picked up by NAD+  
how is acetyl coenzyme A the final product   by combining the resulting acetic acid w. coenzyme A  
what is coenzyme Al   a sulfur-containing coenzyme derived from pantothenic acid , a B-vitamin  
keto acids   when atoms of citic acid are rearranged to produce different intermediate molecules  
what are the products of the Krebs Cycle/Citric acid cycle   2 molecules of carbon dioxide & 4 molecules of reduced coenzymes (3NADH + H+ & 1 FADH2)  
electon transport chain   oversees the final catabolic reations that occur on the inner mitochondrial membranes  
whats going on during the ETC   the hydrogens removed during the oxidation of food fuels are finally combined w. molecular oxygen, & the eergy released during those reactions is harnessed to attach inorganic phosphate groups (Pi) to ADP  
cofactors   proteins bound to metal atoms  
where do flavins derive from   the vitamin riboflavin  
list the sequence energy flows during cellular respiration   glucose-NADH + H+ - electron transport chai - proton motive force - ATP  
the 8 NADH + H+ & the 2 FADH2 produced during the KRebs cycle are "worth"   24 & 4 ATPs  
the 2 NADH + H+ generated during glycolysis yields how many ATP molecules   4 (or 6) ATP molecules  
complete oxidation of 1 glucose molecule to carbon dioxide & water yields   38 or 36 molecules of ATP  
glycogenesis   occurs when (glycolysis is "turned off" by high ATP levels, glucose molecules are combined in long chains to form glycogen);  
how does glycogenesis begin   when glucose entering cells is phosphorylated to glucose-6-phosphate & the coverted innto its isomer, glucose-1-phosphate  
glycogenolysis   occurs when blood levels of glucose drop, glycoge lysis or splitting occurs  
beta oxidation   the initial phase of fatty acid oxidation, ocurs in the mitochondria  
glyceraldehyde is equal to   half a glucose molecule & ATP energy harvest from its complete oxidation is approx. 1/2 that of glucose (18 ATP/glycerol)  
lipogenesis   triglyceride sythesis; occurs when cellular ATP & glucose levels are high  
lypolysis   (fat-splitting); the breakdown of stored fats into glycerol & fatty acids, essentially lipogenesis in reverse  
Before amino acids can be oxidized for energy they must be   deaminated; their amine group (NH2) must be removed; resulting molecule then converted to pyruvic acid or one of the keto acid inntermediates in the Krebs cycle  
what state does the body exist in   dynnamic catabolic-anabolic state  
what are the differences between the carbohydrate/fat pool & the amino acid pool?   1) fats & carbohydrates are oxidized directly to produce cellular energy, whereas a.a. can be used to supply energy only after being converted to a carbohydrate intermediate (keto acid) 2) excess carb. & fat can be stored as such, whereas excess aa are no  
absorptive state   fed state; the time during & shortly after eating, when nutrients are flushing into the bloodstream fm the gastorintestinal tract  
postabsorptive (fasting) state   period when the GI tract is empty & energy sources are supplied by the breakdown of body reabsorbes  
elevated amino acid levels in the blood stimulate   insulin release  
what type of hormone is insulin   a hypoglycemic hormone  
glucose sparinng   the increased use of noncarbohydrate fuel molecules (especially triacylglycerols) to conserve glucose  
glucagon   insulin antagonist  
what type of hormone is glucagon   hyperglycemic hormone; promotes a rise in blood glucose; targets the liver & adipose tissue  
increasing blood sugar levels trigger   insulin release  
which "pushes"___ into the cells   glucose  
blood sugar levels   decline  
when blood sugar levels are low the secrtion of ___ occurs   glucagon  
which ___   pulls glucose from the cells into the blood  
growth hormonne secretion is enhanced by   prolonnged fasting or rapid declines in plasma glucose levles, & it exerts important ant-insulin effects  
list the functions of the liver   1) packages fatty acids into forms that ca be stored or transported 2) synthesizes plasma proteins 3) forms nonessential aa & convertes ammonia resulting from their deamination to urea a less toxic excretory product 4)stores glucose as glycogen & regulate  
cholesterol   dietary lipid; serves as the structural basis of bile salts, steroid hormones & vitamin D & a mj component to plasma membrane  
chylomicrons   transport absorbed lipids from the gastrointestinal tract, considered as a separate class & have the lowest density of all  
what is the role of LDLs   to transport cholesterol tot he peripheral tissues, makinng it available tot he tissue cells for membrane or hormone synthesis & for storage for later use; also regulate cholesterol synthesis in the tissue cells  
what is the function of HDLs   to transport excess cholesterol from peripheral tissues (which do not have the ability to degrade or excrete HDL) to the liver, where it is broken down & becomes part of bile  
HDL is considered   good  
LDL is considered   BAD TO THE BONE!!!  
what is wrong with LDL   it promotes plaque formation that thickens & stiffens the blood vessel walls  
saturated fatty acids stimulate ____ of cholesterola & _____ from the body   liver synthesis; inhibit its excretion  
what is energy intake   total energy output (heat + work + energy storage)  
EI   is considered equal tot eh energy liberated during food oxiation; undigested foods are not part of the equation bc they contribute to no energy  
Energy output   includes the energy (1) immediately lost as heat (about 60% of the total); used to do work ; stored in the form of fat or glycogen  
orexins   a pair of peptides that are powerful appetite enhances  
neuropeptide Y causes   us to crave carbohydrates  
galanin   produces a yen for fats  
GLP-1 & serotonin   (glucagon-like peptide); make us feel full & satisfied  
when we eat plasma glucose levels ___ & cellular metabolism of glucose __   increases; increases  
elevated plasma levels of amino acids ___ eating; wheras low amino acid levels in blood ___ it.   depress eating; stimulate it  
insulin released during food absorption has what effect on hunger   depresses hunger  
glucagon levels rise during what type of behavior   fasting; stimulate hunger  
when is epinephrine release & what does it trigger   (released during fasting); triggers hunger  
what is cholecystokinin & what effect does it have on hunger?   a hormone released in the intestines; it is secreted during food digestion which depresses hunger  
increased body temperature may have what effect on hunger   it may inhibit it  
leptin   the overall satiety signal; secreted over a period of hours exclusively by fat tissue in response to an increase in fatty mass in the body; regulated by glucocorticoids & insulin  
what does leptin bind to   receptors in the choroid plexuses of the ventricles, where it gains entry to the brain  
leptin acts on the   hypothalamus  
what does it regulate   the amount of body fat via controls of appetite & energy output  
what is leptins main target of action   the ventromedial hypothalamus, where it suppresses the secretion of nneuropeptide Y (NPY); the most potent appetite stimulant known  
therefore with all that said & done leptin pretty much   decreases food intake & cranks up activity & heat production  
metabolic rate   the body's rate of eergy output (usually per hour)  
calorimeter   direct method  
respirometer   indirect method; measure oxygen consumption, which is directly proportional to heat production  
BMR(basal metabolic rate)   the measurement obtained; reflects the energy the body nees to perform only its most essential activities  
the taller or thinner person will have a ___ BMR than a shorter fatter person   higher  
thyroxine   produced by thyroid gland; important in determing BMR; metabolic hormone  
TMR (total metabolic rate)   a total rate of kilocalorie connsumption to fuel all ongoing-activities--involuntary & voluntary  
dietary/food-induced thermogenesis   when food ingestion induces a rapid increase in TMR; is greates when proteins are eatten  
radiation   loss of heat in the form of infrared waves (thermal energy); close to 1/2 of body heat loss occurs by radiation  
conduction   transfer of heat between objects that are in direct contact w. each other; ex. when we step into a hot tup, some of the heat of the water is transferred to our skin; conduction requires molecule-to-molecule contact of objectes; thermal energy must move th  
convection   substantially enhances heat exchange from teh body surface tot eh air bc the cooler air absorbs heat by conduction more rapidly than the already-warmed air  
the hypothalamus receives afferent input from   peripheral thermoreceptors & central thermoreceptors  
the hypothalmus respons the heat promoting or heat loss activites via   autonomic effector pathways  
vasoconstriction of cuanneous blood vessels   blood is restricted to deep body areas & largely bypasses the skin; heat loss from the shell is dramatically reduced & shell temp drops toard that of the external environment  
increase in metabolic rate   (blank)  
cold stimulates the relae of   norepinephrine; elevates the metabolic rate; which enhances heat production (known as chemical; nonshivering thermogenesis)  
shivering   increases body temp bc muscle activity produces large amounts of heat  
enhanced thyroxine release   occurs when envir temp decreases gradually; hypothalamus releases thyrotropin-releasing hormonne; increases metabolic rate body heat production increases allowing us to maintain a constannt body tempin cold envir condtions  
vasodilation of cutaneous blood vessels   allows vessels to dialate; skin swell w warm blood, heat is lost from the shell by radiation, conduction & convection  
enhanced sweatinng   occurs when body is overheated & heat cannot be lost by other means; evaporation  
fever is controlled   hyperthermia; results from infection; occurs when wbc & macrophages release PYROGENS (fire starters)  


   






 
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