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A&P - Ch 24

Nutrition, Metabolism, and Body Temp Regulation

organic molecule that stores and releases chemical energy for use in body cells ATP
how energy value of food is measured; amount of heat energy needed to raise body temp of 1kg of water 1degree C kilocalories
chemical substances taken in via the diet that are used for energy and cell building nutrients
carbohydrates, lipids, & proteins major nutrients
vitamins, minerals, & water other nutrients
chemicals that must be obtained from outside sources because they cannot be made fast enough to meet needs of body essential nutrients
except for lactose & negligible amounts of glycogen in meats all carbs ingested are derived from plants
monosaccharides & disaccharides come from fruits, sugar can, sugar beets, honey & milk
polysaccharide, plentiful in most veges; not digested by humans but provides roughage cellulose
insoluble fiber roughage
increases bulk of stool & facilitates defecation insoluble fiber
reduces blood cholesterol levels; pectin found in apples & citrus fruits soluble fiber
glucose is principal __ __ blood sugar
carbohydrate molecule ultimately used as fuel by body cells to produce ATP; monosaccharide glucose
yield of fructose & galactose, during carbohydrate digestion, are converted to glucose by liver before entering general circulation
RBCs & neurons rely __ __ on glucose for their energy needs almost entirely
small amounts of __ __ are used to synthesize nucleic acids pentose sugars
variety of sugars are attached to externally facing plasma membrane __ & __ proteins; lipids
100 grams of carbs/day is presumed to be __ __ needed to maintain adequate blood glucose levels smallest amount
130 g/day of carbs, based on amount needed to fuel brain not total amount needed to supply all daily activities recommended dietary allowance
45-65% of one's total calorie intake with emphasis on complex carbohydrates is the recommended carb intake to maintain overall health
when less than 50 g/day, of carbs, is consumed tissue proteins & fats are used for energy fuel
most abundant dietary lipid triglycerides
triglycerides aka neutral fats or triacylglycerols
fats found in meat & dairy foods saturated
fats found in seeds, nuts, olive/vege oils unsaturated
fats are digested to monoglycerides or all the way to fatty acids & glycerol
once fats are digested into fatty acids & glycerol they are __ to triglycerides for transportation in lymph reconverted
egg yolk, meats, organ meats, shellfish, milk products are major sources of cholesterol
liver produces about 85% of __ __ regardless of dietary intake blood cholesterol
liver __ synthesize linoleic acid cannot
fatty acid component of lecithin; omega-6 fatty acid; essential fatty acid that must be ingested; found in vegetable oils linoleic acid
any of a group of phospholipids found in egg yolks & plasma membrane of plant & animal cells lecithin
bread, cereal, crackers, flour, pasta, nuts, rice, potatoes are all considered complex carbohydrates
carbonated drinks, candy, fruit, ice cream, pudding, young/immature vegetables simple carbohydrates
eggs, milk, milk products, meat (incl. fish, poultry, pork, beef, lamb) are considered complete proteins
legumes (incl. soybeans, lima beans, kidney beans, lentils) nuts & seeds, grains & cereals, & vegetables are considered incomplete proteins
dietary fats are essential because they help body absorb __ __ fat-soluble vitamins
dietary fats are essential because triglycerides are major energy fuel of __ & __ __ hepatocytes; skeletal muscles
dietary fats are essential because phospholipids are integral component of myelin sheaths & cellular membranes
fatty deposits in adipose tissue provide __ __ around body organs protective cushion
fatty deposits in adipose tissue provide __ __ beneath skin insulating layer
fatty deposits in adipose tissue provide easy-to-store __ __ of energy fuel concentrated source
cholesterol is __ __ for energy not used
regulatory molecule formed from linoleic acid via arachidonic acid, which play role in smooth muscle contraction, control of BP, & inflammation prostaglandins
cholesterol is __ component of plasma membranes stabilizing
cholesterol is __ from which bile salts, steroid hormones & other essential molecules are formed precursor
should represent 30% or less of total daily fat intake fats
should be limited to 10% or less of total daily fat intake saturated fats
should be no more than 300 mg daily cholesterol intake
should be less than 200 mg/dl total blood cholesterol
contain highest-quality proteins, those with greatest amount & best ratios of essential amino acids animal products
complete proteins meet all of the body's __ __ requirements for tissue maintenance & growth amino acid
incomplete proteins are nutritionally incomplete because they are low in one or more of the essential amino acids
important structural material of body in skin protein keratin
important structural material of body in CT protein collagen
important structural material of body in muscle protein elastin
enzymes & some hormones that regulate variety of body functions are functional proteins
all amino acids needed to make particular protein must be present in cell at same time & in same amounts; if one missing protein cannot be made all-or-none rule
because essential amino acids cannot be stored those not used immediately to build proteins are oxidized for energy or converted to carbs/fats
for optimal protein synthesis diet must supply sufficient carb/fat calories for ATP production; when doesn't dietary & tissue proteins used for energy adequacy of caloric intake
homeostatic state; rate of protein synthesis equals rate of protein breakdown & loss nitrogen balance
body is in nitrogen balance when amount of nitrogen ingested in proteins equals amount excreted in urine & feces
when amount of protein incorporated into tissue is greater than amount being broken down & used for energy positive nitrogen balance
positive nitrogen balance is found in growing children & pregnant women
positive nitrogen balance also occurs when tissues are being repaired, following illness/injury
protein breakdown for energy exceeds amount of protein being incorporated into tissues negative nitrogen balance
negative nitrogen balance occurs during physical & emotional stress (i.e. infection, injury, or burns)
negative nitrogen balance occurs when __ or __ of dietary protein is poor quality; quantity
negative nitrogen balance can occur during __ starvation
hormones that accelerate protein synthesis & growth anabolic hormones
effects of anabolic hormones __ __ throughout life vary continually
stimulates tissue growth during childhood & conserves protein in adults pituitary growth hormone
trigger growth spurts of adolescence sex hormones
hormones released during stress; enhance protein breakdown & conversion of amino acids to glucose adrenal glucocorticoids
supply essential amino acids; furnish raw material for making nonessential amino acids & various nonprotein nitrogen-containing substances dietary proteins
reflects his/her age, size, metabolic rate, & current state of nitrogen balance amount of protein a person needs
nutritionists recommend __ __ __ of 0.8 g per kg of body weight daily protein intake
organic compounds required by body in minute amounts; not used for energy & do not serve as building blocks, but are crucial in helping body use nutrients that do vitamins
nonprotein substance associated with and activating an enzyme, typically a vitamin coenzyme
most vitamins __ __ coenzymes function as
act as coenzymes in oxidation of glucose for energy B vitamins
most vitamins are not made in the body
vitamin D, small amounts of B vitamins & vitamin K are made in the body
synthesized by intestinal bacteria vitamin K
body can convert beta-carotene into vitamin A
beta-carotene, and substances like it, are call provitamins
no one food contains all the required vitamins
B-complex vitamins & vitamin C are water-soluble vitamins
in order to be absorbed, vitamin B12 must bind to __ __ in stomach secretions intrinsic factor
vitamins A, D, E, & K bind to ingested lipids & are absorbed along with their digestion products fat-soluble vitamins
anything that interferes with fat absorption also interferes with absorption of fat-soluble vitamins
with exception of __ __, fat soluble-vitamins are stored in the body vitamin K
vitamins C, E, & A & mineral selenium are __ that neutralize tissue-damaging free radicals antioxidants
inorganic chemical compounds found in nature; salts minerals
calcium, phosphorus, potassium, sulfur, sodium, chlorine, magnesium & trace amounts of about a dozen other minerals are required in moderate amounts in the body
sum total of chemical reactions occurring in body cells metabolism
energy-requiring building phase of metabolism in which simpler substances are combined to form more complex substances anabolism
process in which living cells break down substances into simpler substances catabolism
metabolic processes in which ATP is produced cellular respiration
chemical reaction in which a phosphate molecule is added to a molecule phosphorylation
phosphorylation __ the molecule to change in a way that increases it activity, produces motion, or does work primes
essential for oxygen binding to hemoglobin iron
harden bone & teeth calcium, phosphorus & magnesium salts
necessary for thyroid hormone synthesis iodine
major electrolytes in the blood sodium & chloride
digestion in GI tract; absorbed nutrients are then transported in blood to tissue cells stage 1 in processing of energy-containing nutrients
during stage 2 of processing of energy-containing nutrients, which occurs in tissue cells, newly delivered nutrients can be built into lipids, proteins, & glycogen by anabolic pathways
during stage 2 of processing of energy-containing nutrients, which occurs in tissue cells, newly delivered nutrients can be broken down by __ __ to pyruvic acid & acetyl CoA in cell cytoplasm catabolic pathways
major catabolic pathway of stage 2 of processing of energy-containing nutrients is glycolysis
catabolic breakdown (in mitochondria) of intermediates into CO2, water, & ATP
primary function of cellular respiration is to generate ATP
gain of oxygen or loss of hydrogen oxidation
whichever way oxidation occurs the oxidized substance always __ __ as they more to a substance that more strongly attracts them loses electrons
reaction that couples oxidation of one substance with reduction of another substance oxidation-reduction (redox) reactions
oxidized substances lose energy & reduced substances gain energy as energy-rich electrons are transferred from one substance to the next key of redox reactions
enzymes that catalyze the transfer of oxygen in oxidation-reduction reactions oxidases
catalyze redox reactions in which hydrogen are removed dehydrogenases
C6H12O6 + 6O2 arrow 6H2O + 6CO2 + 38 ATP + heat oxidation of glucose
glycolysis, Krebs cycle, & electron transport chain-oxidative phosphorylation catabolic pathways of glucose
process of ATP synthesis during which an inorganic phosphate group is attached to ADP; occurs via electron transport chain within mitochondria oxidative phosphorylation
occurs in cytosol of cells; series of 10 chemical steps by which glucose is converted to 2 pyruvic acid molecules glycolysis
glycolysis is a(n) __ pathway anaerobic
glycolysis does not use oxygen
glycolysis occurs whether or not oxygen is present
phase 1 of glycolysis sugar activation
phase 2 of glycolysis sugar cleavage
phase 3 of glycolysis sugar oxidation & ATP formation
fate of __ __, during glycolysis, depends in availability of oxygen pyruvic acid
if O2 not available, during glycolysis, pyruvic acid is converted to lactic acid
if O2 available, during glycolysis, pyruvic acid enters aerobic pathways of Krebs cycle & electron transport chain
aerobic metabolic pathway occurring within mitochondria, in which food metabolites are oxidized & CO_2 is liberated, & coenzymes are reduced Krebs cycle
Krebs cycle also called citric acid cycle
glycogen formation when glucose supplies exceed need for ATP synthesis glycogenesis
glycogenesis mostly occurs in liver & skeletal muscles
glycogen breakdown in response to low blood glucose glycogenolysis
glucose formation from noncarbohydrate (glycerol & amino acid) molecules when dietary sources & stores are depleted gluconeogenesis
gluconeogenesis occurs mainly in liver & protects brain against effects of hypoglycemia
energy yield from __ __ is twice that from glucose or protein catabolism fat catabolism
digested fats are transported in lymph as chylomicrons
chylomicrons are __ in plasma by enzymes into fatty acids and glycerol which are taken up by cells hydrolyzed
only triglycerides are routinely oxidized for energy
metabolite enters glycolytic pathway glycerol pathway
takes place in mitochondria; produces acetyl CoA- enter the Krebs cycle beta oxidation of fatty acids
glycerol & fatty acids not needed for energy are stored as triglycerides( mostly in subcutaneous tissues) lipogenesis
in lipogenesis, when cellular ATP & glucose levels are high glucose is stored as triglycerides
when carbohydrates are deficient breakdown of stored fats to glycerol & fatty acids provides fuel for aerobic respiration lipolysis
when carbohydrates are severely deficient lipolysis results in accumulation of acetyl CoAgets converted to ketone bodies in liver
when dietary protein is in excess of that needed for anabolic processes, amino acids are oxidized for energy or converted into fat
results in pyruvic acid & carbohydrate intermediates- enter the Krebs cycle oxidation of Amino Acids
during oxidation of Amino Acids, amine group is removed as toxic ammonia which is converted by liver to urea & excreted by kidney
requires a complete set of amino acids so essential amino acids must be provided in diet protein synthesis
dynamic state in which organic molecules are continuously broken down and rebuilt catabolic-anabolic steady state
during catabolic-anabolic steady state, body nutrient pools of amino acids carbohydrates & fats are interconvertible
used for protein synthesis, gluconeogenesis & supply of energy (after being converted to a carbohydrate intermediates) amino acid pool
are easily interconverted through key intermediates carbohydrate & fat pools
during and shortly after eating, nutrient absorption into blood has occurred absorptive (fed) state
excess metabolites will be transformed into fat when anabolism exceeds catabolism
when the GI tract is empty- energy sources are supplied by breakdown of reserves postabsorptive (fasting) state
Krebs cycle is key pathway in __ __, of metabolism of energy-containing nutrients Stage 3
cellular respiration consists of __ of Stage 2 (metabolism of energy-containing nutrients) and __ __ of Stage 3 glycolysis; all events
generating ATP is __ __ of cellular respiration primary function
cellular respiration traps some of chemical energy of original food molecules in its own high-energy bonds
many reactions that take place within cells are __ reactions oxidation
hydrogen in __, so its lone electron usually spends time orbiting other atoms of molecule electropositive
oxygen is very __, so when oxygen binds with other atoms shared electrons spend more time in oxygen's vicinity electron-hungry
all oxidation of food fuels involves step-by-step removal of pairs of __ atoms from substrate molecules hydrogen
result of oxidation of food fuels, where there is step-by-step removal of pairs of hydrogen atoms from substrate molecules, eventually leaves only carbon dioxide CO2
in oxidation of food fuels, __ __ is final electron acceptor molecular oxygen
in oxidation of food fuels, molecular oxygen combines with removed hydrogen atoms at very __ of process, to form __ end; water
whenever one substance is oxidized, another substance is reduced
as food fuels oxidized, their energy is transferred from one molecule to another, and ultimately to __ to form __ __ ADP; energy-rich ATP
redox reactions are __ by enzymes catalyzed
enzymes require help of __ __, typically derived from one of B vitamins specific coenzymes
enzymes that catalyze removal of hydrogen atoms to oxidize substance cannot accept the hydrogen
coenzymes act as __ __, becoming reduced each time substrate is oxidized hydrogen acceptors
occurs when high-energy phosphate groups are transferred directly from phosphorylated substrates to ADP substrate-level phosphorylation
substrate-level phosphorylation occurs because high-energy bonds attaching phosphate groups to substrates are even more unstable than those in ATP
ATP is synthesized via substrate-level phosphorylation, once during __ and once during each turn of __ __ glycolysis; Krebs cycle
enzymes catalyzing substrate-level phosphorylation are located in __ & __ __ inside mitochondria cytosol; watery matrix
oxidative phosphorylation releases most of energy that is eventually captured in ATP bonds during cellular respiration
oxidative phosphorylation is carried out by __ __ __ forming part of inner mitochondrial membrane electron transport proteins
couple movement of substances across membranes to chemical reactions chemiosmotic processes
oxidation of food fuels is __ part of chemiosmotic chemi
chemi part of chemiosmotic is used to __ __ across inner mitochondrial membrane into intermembrane space pump protons (H+)
chemiosmotic processes create __ __ __ for protons across mitochondrial membrane steep concentration gradient
during chemiosmotic processes, H+ flows back across membrane through membrane channel called ATP synthase
during chemiosmotic processes, when H+ flows back across membrane, some of gradient energy is captured & used to attach phosphate groups to ADP
are eventually turned into glucose all food carbohydrates
glucose enters tissue cells by facilitated diffusion
facilitated diffusion of glucose into tissue cells is greatly enhanced by insulin
upon entry into cell glucose is immediately phosphorylated into glucose-6-phosphate
because most body cells lack enzymes needed to reverse immediate phosphorylation of glucose, upon entry into tissue cells, it effectively traps glucose inside of cells
the only body cells that have enzymes needed to reverse immediate phosphorylation of glucose, upon entry into tissue cells, are intestinal mucosa cells, kidney tubules cells, & liver cells
catabolic & anabolic pathways for carbs all begin with glucose-6-phosphate
glucose is pivotal fuel molecule in __ pathways ATP-producing
exclusive function of electron transport chain is use of oxygen
carries out final catabolic reactions that occur on mitochondrial cristae electron transport chain
when more glucose available than can be oxidized, rising intracellular ATP concentrations eventually inhibit glucose catabolism and begin process that stores glucose as glycogen/fat
accounts for 80-85% of stored energy fat
an important energy source for skeletal muscles that have depleted their own glycogen reserves liver glycogen
fatty acid metabolites; strong organic acids ketones
adrenal cortex, ovaries, & testes use cholesterol to synthesize their steroid hormones
protein synthesis occurs on ribosomes
protein anabolism reflects __ __ at each stage of life hormonal balance
during absorptive state anabolism __ catabolism exceeds
absorbed monosaccharides are delivered directly to the liver
once absorbed monosaccharides are delivered to liver, __ & __ are converted to glucose fructose; galactose
glycogen formed in liver is stored there
most fat synthesized in liver is packaged with proteins as very low density lipoproteins (VLDLs)
very low density lipoproteins (VLDLs) are released to blood to be picked up for storage by adipose tissues
not sequestered by liver enters body cells to be metabolized for energy bloodborne glucose
any excess of bloodborne glucose is stored in __ __ as glycogen or in __ cells as fat skeletal muscles; adipose
enzyme that catalyzes fat hydrolysis & is active in capillaries of muscle & fat tissues lipoprotein lipase
use triglycerides as primary energy source adipose, skeletal & cardiac muscle, & liver cells
most fatty acids & glycerol enter adipose tissue to be __ to triglycerides & stored reconverted
liver __ some amino acids to make them keto acids deaminates
keto acids may be used for __ __ in Krebs cycle, or may be converted to __ __ stores ATP synthesis; liver fat
liver uses some amino acids to synthesize plasma proteins
plasma proteins synthesized from amino acids by liver include albumin, clotting proteins, & transport proteins
most amino acids traveling through liver remain in blood to be used by other cells for protein synthesis
hormone that enhances carrier-mediated diffusion of glucose into tissue cells, thus lowering blood glucose levels insulin
insulin directs essentially all events of absorptive state
rising blood glucose levels after carb-containing meal act as __ __ that prods beta cells of pancreatic islets to secrete more insulin humoral stimulus
glucose-induced stimulation of insulin release (by pancreatic islets) is enhanced by GI tract hormone glucose-dependent insulinotropic peptide (GIP)
glucose-induced stimulation of insulin release (by pancreatic islets) is enhanced by __ stimulation parasympathetic
2nd important stimulus for insulin release is elevated amino acid levels in blood
enhances carrier-mediated facilitated diffusion of glucose translocation of glucose transporter (GLUT-4)
brain & liver cells take up glucose whether or not insulin is present
once glucose enters tissue cells, insulin __ glucose oxidation for energy & __ it conversion to glycogen enhances; stimulates
insulin revs up __ __ of amino acids into cells active transport
insulin __ protein synthesis promotes
insulin __ liver export of glucose inhibits
insulin inhibits virtually all liver enzymes that promote gluconeogenesis
insulin is __ hormone hypoglycemic
insulin sweeps glucose out of blood into tissue cells, in turn lowering glucose levels
consequence of inadequate insulin production or abnormal insulin receptors diabetes mellitus
net synthesis of fat, glycogen, & protein ends & catabolism of these substance begins to occur postabsorptive state
primary goal of postabsorptive state is to maintain blood glucose levels between meals
postabsorptive state promotes use of fats for energy
postabsorptive state spares glucose for brain
liver's glycogen stores are __ __ of glucose reserves used in postabsorptive state 1st line
in postabsorptive state, liver's glycogen stores can maintain blood sugars levels for about 4 hours
in postabsorptive state, 2nd line of glucose reserves tapped into are glycogenolysis in skeletal muscles
before liver glycogen is exhausted, in postabsorptive state, glycogenolysis begins in skeletal muscles
glucose produces by glycogenolysis in skeletal muscles, in postabsorptive state, is not released into blood because skeletal muscles does not enzymes needed to dephosphorylate glucose
during glycogenolysis in skeletal muscles, in postabsorptive state, glucose is __ __ to pyruvic acid partly oxidized
skeletal muscle contributes to blood glucose homeostasis indirectly via liver mechanisms
during lipolysis in adipose tissues & liver, glycerol is used for gluconeogenesis in the liver
when fasting is prolonged & glycogen/fat stores are nearly exhausted tissue proteins become major source of blood glucose
during catabolism of cellular proteins, cellular amino acids are __ & converted to glucose in liver deaminated
during fasting for several weeks, __ also carry out gluconeogenesis & contribute as much glucose to blood as liver kidneys
during prolonged fasting/starvation, __ __ are 1st to be catabolized muscle proteins
determines time a person can survive without food amount of fat body contains
increased use of noncarbohydrate fuel molecules, especially triglycerides, to conserve glucose glucose sparing
as body progresses from absorptive to post absorptive state all other organs, besides __, switch to fatty acids as major energy source brain
during transition phase, from absorptive to post absorptive state, __ begins in adipose tissues & released __ __ are picked up by tissue cells & oxidized for energy lipolysis; fatty acids
important trigger for initiating postabsorptive events is dampening of insulin release
dampening of insulin release occurs as blood glucose levels __ drop
as insulin levels drop, during postabsorptive state, all __ __ responses are inhibited as well insulin-dependent cellular
can improve body's use of insulin, during postabsorptive state drinking moderate amounts of beer, wine, or gin
stimulate alpha cells of pancreatic islets to release glucagon declining glucose levels
hormone formed by alpha cells of pancreatic islets; raises glucose level of blood glucagon
glucagon is __ of insulin antagonist
during postabsorptive state glucagon is considered __ __ hyperglycemic hormone
term used to describe hormones such as glucagon that elevate blood glucose level hyperglycemic
targets of glucagon are liver & adipose tissue
during postabsorptive state, they respond to glucagon by accelerating glycogenolysis & gluconeogenesis hepatocytes in liver
during postabsorptive state, in response to glucagon they mobilize lipolysis & release fatty acids & glycerol to blood adipose cells
during postabsorptive state, glucagon __ blood energy sources by __ both glucose & fatty acid levels restores; enhancing
during postabsorptive state, certain hormonal controls combined with persistent low glucose levels or prolonged fasting, most fat that is mobilized is converted to ketone bodies
glucagon release is __ after next meal or whenever blood glucose levels rise & insulin secretion begins again inhibited
insulin & thyroxine stimulate glucose uptake by cells
insulin & growth hormone stimulate acid uptake by cells
insulin & thyroxine stimulate __ __ for energy glucose catabolism
hormone that stimulates glycogenesis, lipogenesis, & fat storage insulin
insulin inhibits gluconeogenesis
insulin, growth hormone, thyroxine, & testosterone stimulate anabolic protein synthesis
glucagon & epinephrine stimulate glycogenolysis
glucagon, epinephrine, growth hormone, thyroxine, & cortisol stimulate lipolysis & fat mobilization
glucagon, epinephrine, growth hormone, & cortisol __ gluconeogenesis stimulate
cortisol stimulate __ __ breakdown catabolic protein
both insulin & glucagon release are strongly stimulated by rising amino acid levels in blood
when high-protein low carb meal is eaten stimulus for insulin release is strong, & if not counterbalanced may cause damage to brain by abrupt onset of hypoglycemia
when high-protein low carb meal is eaten, simultaneous release of glucagon __ effects of insulin modulates
when high-protein low carb meal is eaten, simultaneous release of glucagon helps __ blood glucose levels stabilize
plays crucial role in supplying food quickly when blood glucose levels drop suddenly sympathetic nervous system
well supplied by sympathetic nerve fibers adipose tissues
epinephrine released by adrenal medulla in response to sympathetic activation acts on liver, skeletal muscles, & adipose tissues
when acting together, sympathetic nerve stimulation & release of epinephrine from its activation mobilize fat & promote glycogenolysis
enhanced by prolonged fasting or rapid declines in blood glucose levels; exerts important anti-insulin effects growth hormone
growth hormone reduces ability of insulin to promote glucose uptake in fat & muscle
function of carbohydrate metabolism in liver, important in maintaining blood glucose homeostasis, is to convert galactose & fructose to glucose
in carbohydrate metabolism, it store glucose as glycogen when blood glucose levels are high & in response to hormonal controls performs glycogenolysis & releases into blood called glucose buffer function
a function of carbohydrate metabolism in liver is gluconeogenesis: conversion of amino acids & glycerol to glucose when glycogen stores are exhausted & blood glucose levels are falling
a function of carbohydrate metabolism in liver is conversion of glucose to fats for storage
function of fat metabolism in liver, primary site of beta oxidation
beta oxidation is breakdown of fatty acids to acetyl CoA
function of fat metabolism in liver, converts excess acetyl CoA to ketone bodies for release to tissue cells
function of fat metabolism in liver, is fat storage
function of fat metabolism in liver, forms __ for transport of fatty acids, fats, & cholesterol to & from tissues lipoproteins
function of fat metabolism in liver, synthesis of cholesterol from __ __ in order to catabolize cholesterol to __ __ which are excreted in bile acetyl CoA; bile salts
without liver metabolism of protein many __ __ would not be made clotting proteins
without lever metabolism of protein __ would not be disposed from the body ammonia
important function of liver, metabolism of protein __ amino acids deaminates
required for amino acid conversion to glucose or use for ATP synthesis; takes place in liver deamination of amino acids
through metabolism of protein by liver, ammonia is removed from body in urea
inability to form urea in liver results in accumulation of ammonia in blood
protein metabolism by liver, forms most __ proteins plasma
if protein metabolism by liver does not take place plasma protein depletion causes rapid mitosis of hepatocytes & actual growth of liver
plasma proteins not formed by liver gamma globulins, some hormones & some enzymes
intraconversion of nonessential amino acids transamination
transamination is liver function brought about by protein metabolism
liver functions to store 1-2 year supply of vitamin A
liver functions to store sizable amounts (1-4 months' supply) of vitamin D & B12
liver functions to store __, stored as ferritin until needed iron
liver releases iron to blood as blood levels drop
biotransformation function of liver includes metabolism of __ & __ by performing synthetic reactions yielding inactive products for excretion by kidneys alcohol; drugs
biotransformation function of liver includes metabolism of alcohol & drugs by performing __ __ that may result in products which are more active, changed in activity, or less active nonsynthetic reactions
the only thing that can do liver's work is a hepatocyte
serves as structural basis of bile salts, steroid hormones, & vitamin D as a major component of plasma membranes cholesterol
cholesterol is part of __ __ molecule that helps direct embryonic development key signaling
about 15% of __ cholesterol comes from diet blood
85% of blood cholesterol is made from __ __ by liver acetyl CoA
intestinal cells also make __ from acetyl CoA cholesterol
because triglycerides & cholesterol are insoluble in water they do not circulate freely in blood
triglycerides & cholesterol are transported to & from tissue cells bound to small __ __ lipid-protein complexes
solubilize hydrophobic lipids, & protein part contains signals that regular lipid entry & exit at specific target cells lipoproteins
in lipoproteins, relative __ __ varies considerably fat-protein composition
contain triglycerides, phospholipids, & cholesterol all lipoproteins
the higher the % of lipid in lipoproteins, to __ its density lower
greater the proportion of protein in lipoproteins, the __ its density higher
class of lipoproteins that transport triglycerides from intestine & liver to adipose & muscle tissues; they contain primarily triglycerides w/some cholesteryl esters very-low-density lipoprotein (VLDL)
class of plasma lipoproteins that transport cholesterol to extrahepatic tissues; high serum levels have been correlated w/premature coronary heart disease low-density lipoprotein (LDL)
class of plasma lipoproteins that promote transport of cholesterol from extrahepatic tissue to liver for excretion in bile; serum levels have been negatively correlated w/premature coronary heart disease high-density lipoprotein (HDL)
liver is __ source of VLDLs primary
once triglycerides are unloaded from liver to peripheral tissues VLDL residues are converted to LDLs
LDLs are considered cholesterol-rich
transport cholesterol to peripheral (non-liver) tissues making it available to tissue cells for membrane/hormone synthesis & for storage for use later role of LDLs
LDLs also regulate __ __ in tissue cells cholesterol synthesis
docking of LDL to LDL receptor triggers __ __ of entire particle receptor-mediated endocytosis
HDLs are particularly rich in phospholipids & cholesterol
major function of __ is to scoop up & transport excess cholesterol from peripheral tissues to liver HDLs
liver make __ __ of HDL particles & then ejects them into bloodstream in collapsed form protein envelopes
once in blood incomplete HDL particles __ __ __ picked up from tissue cells & pulled from artery walls fills with cholesterol
HDL also provides __ organs with raw their material of cholesterol steroid-producing
organs like ovaries & adrenal glands have ability to __ __ cholesterol from HDL particles without engulfing them selectively remove
transport absorbed lipids from GI tract; separate class from lipoproteins; have lowest density of all chylomicrons
chylomicrons come from intestines
VLDLs & LDLs are made by liver
HDLs are returned to liver
are thought to protect against heart attack (good cholesterol) high levels of HDL
increase the risk of heart attack (bad cholesterol) high levels of LDL
partially adjusted amount of cholesterol produced by liver according to amount of cholesterol in diet negative feedback loop
high cholesterol intake inhibits cholesterol production by liver
liver produces __ __ of cholesterol even when dietary intake is high basal amount
saturated fatty acids __ __ synthesis of cholesterol stimulate liver
saturated fatty acids inhibit __ of liver cholesterol from body excretion
unsaturated fatty acids enhance __ of cholesterol & its __ to biles salts excretion; catabolism
unsaturated fatty acids reduce total cholesterol levels
unsaturated __ fatty acids lower proportions of saturated fats & cholesterol omega-3
healthy oils that have been hardened by hydrogenation to make them more solid; cause serum changes worse than those cause by saturated fats trans fats
spark greater increase in LDLs & greater reductions in HDLs, producing unhealthiest ratio of total cholesterol to HDL trans fatty acids
energy liberated during food oxidation energy intake
sum of energy lost as heat (60%), as work (driven by ATP), and as fat or glycogen storage energy output
nearly all energy derived from food stuffs is eventually converted to heat
heat is lost during every cellular activity
cells cannot use it to do work, it warms the tissues and blood heat energy
heat energy helps maintain __ __ temperature homeostatic body
heat energy allows __ __ to occur efficiently metabolic reactions
important part of energy equation only during periods of growth & net fat deposit energy storage
when energy intake/output are balanced body weight remains stable
nuclei in __ regulate hunger & satiety hypothalamus
vagus nerve delivers neural signals from __ __ to hypothalamus digestive tract
rising blood levels of glucose, amino acids, fatty acids send signals to brain indicating fullness
chemoreceptors respond to hormones, like glucose, insulin, etc.
released from fat cells; suppress hunger insulin & leptin
glucagon stimulates __ hunger
body temperature & psychological factors increase or inhibits __, to a lesser degree eating
reflects energy body needs to perform its most essential activities; such as breathing & resting level of organ function; ‘the cost of living’ basal metabolic rate (BMR)
energy body needs to fuel all ongoing activities total metabolic rate (TMR)
hormone released by fat cells that signals satiety leptin
involves neural signals from GI tract, blood levels of nutrients, & GI tract hormones; target hypothalamic centers via solitary tract/nucleus of brain stem short-term regulation of appetite & feeding behaviors
activation stretch receptors ultimately inhibits appetite, because GI Tract distention sends signals along vagus nerve afferents that suppresses appetite-enhancing/hunger center long-term regulation of appetite & feeding behaviors
rising blood glucose, elevated blood levels of amino acids, & blood concentration of fatty acids are all nutrient signals that indicate fullness or satiety
during fasting & hypoglycemia the activation of glucose receptors in brain that ultimately depress eating are absent resulting in hunger & turn-on of food-seeking behaviors
larger the amount of fatty acids in blood, the greater the inhibition of eating behavior
insulin & cholecystokinin (CCK) are __ __ released during food absorption, & act as satiety signals to depress hunger gut hormones
glucagon & epinephrine levels __ during fasting rise
powerful appetite stimulant, produced by stomach; trigger for meal initiation; levels peak just before mealtime, troughs after meals Ghrelin (Ghr)
the hormone leptin is __ __ of long-term control of feeding behavior key component
leptin is secreted exclusively by adipose cells in response to a(n) increase in body fat mass
leptin serves as an indicator of body's total energy stores in fat tissue
energy expended by the body per unit time; total heat produced by all chemical reactions & mechanical work of body metabolic rate
device used for measuring quantities of heat generated by friction, chemical reaction, or the human body calorimeter
calorimeter is considered __ __ of measurement of metabolic rate direct method
used to measure oxygen consumption, which is directly proportional to heat production respirometer
respirometer is considered __ __ of measurement of metabolic rate indirect method
metabolic rate is measured when a person is in postabsorptive state (at least 12hrs w/out food)
most important hormonal factor in determining BMR is the amount of thyroxine released by thyroid gland
direct effect of thyroxine on most body cells, except brain cells, is to increase O2 consumption & heat production
thyroxine increases O2 consumption & heat production by accelerating use of ATP to operate sodium-potassium pump
results in slowed metabolism, obesity, & diminishes thought processes hypothyroidism
catabolize stored fats & tissue proteins, weight loss despite food intake, bones weaken & muscles begin to atrophy hyperthyroidism
BMR account for __ __ of TMR large part
skeletal muscle activity causes most dramatic short-term changes in TMR
food ingestion induces __ __ in TMR rapid increase
rapid increase in TMR from food ingestion, is an effect called food-induced thermogenesis
food-induced thermogenesis is greatest when proteins are ingested
as ratio of body surface area to volume __, BMR increases increases
2 people of same weight __ will have more BMR taller
BMR decreases with age
BMR increases with temperature or stress
BMR in males is higher
__ hormone increases BMR thyroid
reflects balance btwn heat production & heat loss body temperature
liver, heart, brain, & endocrine organs generate most heat when body at rest
heat production from skeletal muscles increases 30-40 times that of rest of body during exercise
37°C (98.6°F) normal body temperature
occurs at 37°C (98.6°F) optimal enzyme activity
beta oxidation results in fatty acid chains being broken down
glycolysis results in pyruvic acid
Krebs cycle initial metabolite is citric acid
oxidative phosphorylation requires ATP synthase at end
comprised of simple sugars; used as major fuel source for cellular respiration carbohydrate
comprised of amino acids; used to build structural components of cells as well as functional components (enzymes) protein
comprised of fatty acids & glycerol; should be 20%-35% of caloric intake lipids
comprised of electrolytes; important as cofactors minerals
small organic molecules; important as coenzymes; fat-soluble forms are A, D, E, and K vitamins
carbohydrates provide primary source of fuel for ATP synthesis
lipids act as an accessory fuel; component of membranes
proteins important structural material (keratin, collagen, etc.) and functional material (enzymes, etc.)
vitamins most function as coenzymes; not used as structural components
minerals incorporation into some body structures; used in conjunction with enzymes
water solvent for chemical reactions in body
vitamin A required for synthesis of photoreceptor pigments in vision; integrity of skin, mucosae, & normal bone; tooth development
vitamin E primarily an antioxidant preventing oxidative damage to cell membranes & atherosclerosis
vitamin D enhances absorption of calcium; works in conjunction with hormones regulating calcium blood levels
vitamin K essential for formation of clotting proteins; intermediate in electron transport; participates in oxidative phosphorylation
vitamin C important in formation of connective tissues; antioxidant; conversion of tryptophan to serotonin; conversion of cholesterol to bile salts
vitamin B1 (thiamine) acts as coenzyme in carbohydrate metabolism; required to transform pyruvic acid to acetyl CoA; oxidation of alcohol
vitamin B2 (riboflavin) acts as hydrogen acceptor in electron transport (FAD and FMN); component of amino-acid oxidases
niacin acts as hydrogen acceptor in electron transport (NAD) during glycolysis & Krebs cycle; inhibits cholesterol synthesis; peripheral vasodilator
folic acid basis of coenzymes in formation of certain amino acids, choline, DNA, RBCs, & normal neural tube development in embryo
vitamin B12 functions as coenzyme in all cells; acts in synthesis of DNA; essential for erythrocyte division during RBC production
food sources of calcium milk, milk products, leafy green vegetables, egg yolk, shellfish
food sources of sulfur meat, milk, eggs, legumes
food sources of potassium avocados, dried apricots, meat, fish, fowl, cereals, bananas
food sources of sodium cured meats, sauerkraut, cheese
food sources of magnesium milk, dairy products, whole grain cereals, nuts, legumes, leafy green vegetables
food sources of phosphorus diets rich in proteins; milk, eggs meat, fish, poultry, legumes, nuts, whole grains
two molecules of pyruvic acid and two NADH + H+ products of glycolysis
five carbon dioxide molecules and ten molecules of reduced coenzymes (NADH + H+ and FADH2) products of Krebs cycle
36 ATP and 12 H2O molecules products of electron transport chain & oxidative phosphorylation
major means for conserving heat is vasoconstriction of cutaneous blood vessels
in glycolysis, glucose must be activated with the use of 2 ATP molecules
most vitamins function as coenzymes in the body; coenzymes help catalyze chemical reactions
one function of vitamin A is to form visual pigments
are derived from vitamin A retinol in the rods and cones
thyroxine is hormone responsible for setting the basal metabolic rate
site of electron transport is mitochondrial inner membrane (cristae)
inner membrane of the mitochondrion contains integral proteins necessary for electron transport
coenzyme reduced in both glycolysis and the Krebs cycle NAD
element is considered a trace mineral chromium
lipoprotein contains high levels of cholesterol LDL
LDL is nearly 1/2 cholesterol
nutritionally incomplete protein lacks one of the essential amino acids needed by the body
most of the ATP produced during cellular respiration is produced by oxidative phosphorylation during electron transport
mobilize glucose reserves by glycogenolysis function of the liver during the post-absorptive state
insulin is hormone that controls essentially all events of the absorptive state
factor that makes it harder for an obese person to lose weight increase in alpha receptors (the kind that favor fat accumulation) in fat cells
BMR is amount of energy the body needs to maintain life
shivering is physiological response to hypothermia
prolonged high protein intake can lead to loss of bone mass
beta-carotene is considered a provitamin
fat-soluble vitamin, which is eliminated by the kidney and, therefore is not stored in the body vitamin K
two molecules of pyruvic acid, two molecules of NAD+, and a net gain of two ATP is final product of glycolysis
cyanide acts as a poison by interfering with the flow of electrons in the electron transport chain
blood glucose is maintained by gluconeogenesis when fasting for several weeks
low-density lipoprotein would contain high lipid content
role of high-density lipoproteins is to transport excessive cholesterol from peripheral tissue to the liver, where it is broken down and becomes part of bile
official medical measurement of obesity is body mass index
leptin acts to suppress appetite by inhibiting neuropeptide Y, which is the most-powerful known appetite stimulant
in a redox reaction coenzymes accept hydrogen
ascorbic acid (vitamin C) is an antioxidant
fermentation occurs when oxygen is NOT available
in glycolysis, glucose is initially cleaved into two, three-carbon groups
in order for amino acids to be converted into lipids, they must be deaminated
oxidative phosphorylation is coupled to chemiosmosis
electron transport causes a chemiosmotic gradient, which causes oxidative phosphorylation of ADP to ATP
before lipids can be metabolized fatty acids must undergo beta oxidation to be converted into two-carbon acetic acid fragments
gluconeogenesis is formation of glucose from noncarbohydrate precursors
major function of HDL is to transport excess cholesterol from peripheral tissues to the liver
calcium is a mineral
glucose is exclusive energy source for neurons
cholesterol serves as precursor to hormones and maintains the fluidity of the plasma membrane
protein is used to build enzymes
vitamins can function as coenzymes
person who is starving is likely to exhibit negative nitrogen balance
if consumed in large quantities fat-soluble vitamins can be toxic
Krebs cycle generates rich supply of the reduced coenzymes, NADH and FADH2
final electron acceptor in the electron transport chain is O2
glycogenesis formation of glycogen to store glucose
glycogenolysis cleavage of glycogen to release glucose
gluconeogenesis process of forming new glucose from noncarbohydrate molecules
beta oxidation starts phase of fatty acid breakdown
lipogenesis triglyceride synthesis
as proteins are broken down for energy __ is generated; the liver then converts this potentially toxic intermediate into __ ammonia; urea
in the absorptive state insulin serves as regulatory hormone
in the postabsorptive state glycogen is broken down to release glucose
leptin is considered long-term regulator of food intake
Created by: lfrancois



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