chapter 25: metabolism Flashcards
what occurs when cells use enzymes & water to catabolize the chemical bonds of large organic molecules to produce monomer molecules?
hydrolysis
aerobic cellular respiration functions to catabolize oxygen and glucose into
what & what to harvest bond energy to make ATP?
carbon dioxide(CO2) & water (H2O)
there is a net gain of what ATP molecules by substrate level phosphorylation during complete aerobic cellular respiration?
4
32 ATP molecules can be made by what phosphorylation at the
Electron Transport system?
oxidative
when glucose or pyruvic acid is oxidized in complete aerobic cellular respiration,
what gets reduced?
NAD (becomes NADH)
the synthesis of glucose from something not carbohydrate is called
what?
glucogenesis
when catabolizing lipids for energy, the glycerol is converted into what for entry into decarboxylation & the citric acid cycle?
pyruvic acid
beta-oxidation of fatty acids produces what?
acetyl
how do your cells acquire linolenic acid & what do they use it for?
from food (seeds nuts and fish are best) ; to synthesize arachidonic acid in order to make eicosanoids
chylomicrons are made by the what epithelium to deliver lipids to what organ?
intestinal epithelium; liver
what are created by the liver to deliver triglycerides to the tissues, particularly adipose for storage?
VLDLs (very low density lipoproteins)
LDLs are typically increased by a diet that contains a lot of what kind of fats?
saturated
deamination of amino acids initially produces what which must be converted into urea by the liver?
ammonia
what is meant by an amino acid being an essential amino acid?
must be ingested, cells can’t make it (or produce it in sufficient quantity to meet needs)
purine bases of RNA are deaminated & excreted as what?
uric acid
glycogen reserves are found in the liver and what muscle?
skeletal muscle
neurons process only what for energy?
glucose
what’s the hormone that promotes glucose utilization during the absorptive state?
insulin
during the post-absorptive state, the liver converts amino acids and fatty acids
into what bodies to supply body cells with substrates for energy production?
ketone
during the absorptive state, growth hormones promote the absorption of amino acids & protein synthesis; what does it do during the post-absorptive state?
inhibits glucose use, promotes fatty acid use
why might you produce oddly colored urine shortly after taking a multivitamin?
water-soluble vitamins that are not used immediately are excreted by the kidney; some have colors (multivitamins usually contain far more of each vitamin that the body can use in a few hours)
a Calorie is measured as what?
energy needed to raise 1 kg of water 1 degree centigrade
a normal, healthy BMI for an average-sized person would between what range?
18-25
why is 110 degrees Fahrenheit too hot a body temperature for a human?
critical proteins denature, loss of homeostasis
what is most of the body’s heat lost by?
radiation
what is nonshivering thermogenesis?
elevation in metabolic rate of cells to produce heat through cellular respiration
what are the cytokines that initiate fever by resetting the thermostat in the hypothalamus?
pyrogens
which person is likely to lose more heat faster: someone 6 feet tall & 150 pounds or someone 4 feet tall & 150 pounds?
the tall thin one
metabolism
sum of all chemical reactions in body
-digestion + Absorption by GI -> monomers (building blocks) for ATP or biomolecule synthesis
catabolism
breakdown of organics
*supplies ATP & monomers to drive anabolism
hydrolysis (catabolism)
large molecules into
monomers
cellular respiration (catabolism)
oxidation of monomers in mitochondria
-40% of energy -> ATP
-60% of energy -> heat
anabolism
synthesis of new organics
-cell maintenance and repair
-growth
-formation of secretions
-nutrient reserves
carbohydrate anabolism
all carbohydrates & lactic acid can be converted to glucose
gluconeogenesis
synthesis of glucose
from a non-carbohydrate precursor, ex: glycerol, amino acids
functions of glucose
-stored as glycogen
-used to generate ATP
-to create other carbohydrates (cell membranes receptors, nucleic acids)
lipid catabolism (lipid metabolism)
-triglycerides most common
-lipolysis
-include fatty acids & glycerol
lipolysis (lipid catabolism -> lipid metabolism)
triglyceride -> glycerol + 3 fatty acids
glycerol (lipid catabolism -> lipid metabolism)
glycerol -> pyruvic acid -> citirc acid cycle
-generates 18 ATP
fatty acids (lipid catabolism -> lipid metabolism)
undergo β-oxidation to
become 2-carbon acetyl, each 2-C fragment generates 17
ATP
lipid metabolism
-lipolysis common to hepatocytes, cardiac muscle, skeletal muscle for ATP synthesis
-not possible in neurons
-not water soluble, difficult for enzymes to access
-lipolysis requires oxygen for ATP synthesis, no fermentation
glycolysis (aerobic cellular respiration)
-anaerobic in cytoplasm
- 1 glucose oxidized catabolized into 2 pyruvic acids
- 2 NADH produced by reduction of 2 NAD via oxidation of glucose
-2 ATP produced by substrate-level phosphorylation
-if no O2 pyruvic acid is reduced to lactic acid (fermentation)
erythrocytes (RBCs) (glycolysis)
glycolysis only (no mitochondria)
skeletal muscle (glycolysis)
fermentation when no O2
neurons & cardiac muscle (glycolysis)
can’t ferment, need O2, must always do complete aerobic respiration of glucose
decarboxylation (aerobic cellular respiration)
-occurs in matrix of mitochondria
-2 pyruvic acid decarboxylated & oxidized into 2 acetyl + CO A + 2 CO2 with NADH
*2 times
citric acid cycle/krebs cycle (aerobic cellular respiration)
-occurs in matrix of mitochondria
-2 acetyl + 2 oxaloacetate acids = 2 citric acids
-citric acid decarboxylated & oxidized producing 4 CO2, 6 NADH, 2 FADH2
-2 ATP generated by substrate-level phosphorylation (glucose no longer exists)
electron transport (aerobic cellular respiration)
-aerobic, occurs on cristae of mitochondria
-NADH & FADH2 (reduced during glycolysis & krebs cycle) are oxidized
-electrons (H) are passed to ETC (cytochromes), finally accepted by oxygen
-32 ATP created
-12H2O produced for oxygen waste
how many ATP’s will glucose make with oxygen?
1 glucose will produce 36 ATP in most human tissue cells
how many ATP’s will glucose make without oxygen?
1 glucose will produce 2 ATP (glycolysis & lactic acid) in human cells capable of fermentation (not neurons or cardiac muscle)
unsaturated fats
two covalent bonds (unhealthy)
saturated fats
single covalent bond (healthy)
lipogenesis (lipid anabolism)
triglycerides synthesized from cellular respiration intermediate
-glycerol from glycolysis products
-fatty acids from acetyl Co A
cholesterol synthesis (lipid anabolism)
from any saturated fat molecule
essential fatty acids
must be ingested in diet, no synthesis
a. linolenic acid
b.linoleic acid
-both used to synthesize arachidonic acid, to synthesize eicosanoids (leukotrienes & prostaglandins) for cell signaling
linolenic acid
omega 3 fatty acid
linoleic acid
omega 6 fatty acid
functions of lipids
-catabolism to generate ATP (triglycerides)
-cell membranes (phospholipids, glycolipids, cholesterol)
-myelin sheaths on axons
-bile salts & steroid hormones
-cell signaling molecules
-energy reserve (80% triglycerides)
-insulation & protection
lipid transport (lipid anabolism)
-free fatty acids bound to albumins in blood
-other bound to proteins to form lipoproteins: soluble, bind specific receptors
-five classes
five class of lipoproteins based on size & composition:
high protein content = high density
high lipid content = low density
chylomicrons (lipoproteins class)
95% triglycerides, from intestinal epithelium, deliver lipids from gut to liver
-travel by lymph
very low-density lipoproteins (VLDLs) (lipoprotein class)
triglycerides (high levels), phospholipids, cholesterol; delivers triglycerides from liver to tissue
intermediate density lipoproteins (IDLs) (lipoprotein class)
VLDLs with triglycerides removed to return to liver processing
low-density lipoproteins (LDLs) (lipoprotein class)
high cholesterol, low triglycerides & phospholipids, deliver cholesterol from liver to tissues (unhealthy)
high-density lipoproteins (HDLs) (lipoprotein class)
equal protein & lipids (cholesterol & phospholipids), return cholesterol to liver for degradation (healthy)
lipoprotein distribution events 1-3
- liver synthesizes VLDLs & releases them into blood
- triglycerides are removed in capillaries, making IDLs from VLDLs
- IDLs return to liver, triglycerides removed & proteins altered making LDLs from IDLs which are released to blood
lipoprotein distribution events 4-6
- LDLs travel to peripheral tissue
- cells endocytose LDLs & break them down
- extra cholesterol diffuses out of cells & enters blood
lipoprotein distribution events 7-9
- cholesterol binds to HDLs in blood & returns to liver
- HDLs in liver have cholesterol extracted to form empty HDLs, new LDLs & bile salts
- empty HDLs return to blood to pick up free cholesterol
diet rich in saturated fats (animals) (cholesterol & health) ->
triggers synthesis of cholesterol & blocks excretion/ conversion by liver
diet rich in non-hydrogenated unsaturated fats (plants) (cholesterol & health) ->
enhance excretion & conversion to bile salts
protein metabolism
-amino acids usually recycled into new proteins
-when carbs & lipids lacking or amino acids are in excess, can be catabolized for ATP or stored as fat
deamination (amino acid catabolism)
amino group removed requires VitB6
amino acid catabolism (protein metabolism)
-deamination
-generates ammonia, toxic, converted by liver to urea, excreted in urine
-carbon chain -> Krebs cycle for ATP
-different amino acids produce different amounts of ATP
protein starvation (amino acid catabolism)
catabolism difficult, inefficient & toxic, last resort for energy
essential amino acids (amino acid anabolism)
- 8 for adults, 10 for children
-must be ingested, no synthesis
synthesis (amino acid anabolism)
-12 can be synthesized using carbon backbone from other amino acids
-amination
amination (amino acid anabolism)
addition of amino group
phenylketonuria
lack enzyme to convert phenylalanine to tyrosine, tyrosine needed for melanin, deaminated phenylalanine level rise -> neurotoxic
functions of proteins
-cell structural components
-enzymes
-hormones
nucleic acid metabolism
-nucleotides usually recycled for new nucleic acids
- DNA never catabolized, only RNA under extreme conditions
-nucleotide hydrolyzed to pentose sugar, nitrogenous base & phosphate
nucleic acid metabolism of pentose sugar, nitrogenous base & phosphate:
-sugar -> glycolysis for ATP
-pyrimidine bases (C, U) -> acetyl -> citric acid cycle for ATP
-purine bases (A, G) -> deaminated, excreted as uric acid, not used for ATP
gout
crystal of uric acid in joints, pain & swelling
liver (metabolic interaction-1st region for metabolism)
-site of metabolic regulation & control
-can break down or synthesize most molecules for use by other cells
-store glycogen reserves
adipose (metabolic interaction- 2nd region region for metabolism)
stores triglycerides reserves
skeletal muscle (metabolic interaction- 3rd region region for metabolism)
-stores glycogen reserves
-has contractile proteins that can be catabolized (release amino acids)
neural tissue (metabolic interaction- 4th region region for metabolism)
-high energy demand but noo reserves
-requires constant supply of glucose -> oxygen
peripheral tissues (metabolic interaction- 5th region region for metabolism)
-no reserves
-catabolizes a wide range of substrates
absorptive state (pattern of metabolic state)
-anabolism exceeds catabolism
-occurs for ~4hr post meal while nutrients are being transported to liver then tissues
-some nutrients are immediately, some stored as reserves
insulin (hormone involved in absorptive state -> pattern of metabolic state)
promotes glucose uptake & utilizations by cells
growth hormone (hormone involved in absorptive state -> pattern of metabolic state)
promotes amino acid uptake & protein synthesis by cells
androgens & estrogens (hormone involved in absorptive state -> pattern of metabolic state)
promote amino acid utilization in protein synthesis
liver tissue regulates blood glucose levels (tissue involved in absorptive state -> pattern of metabolic state):
-removes excess glucose from blood & performs glycogenesis (formation of glycogen from glucose)
-excess glucose converted into triglycerides & converted to VLDLs for storage in adipocytes
liver tissue when amino acids not tightly regulated (tissue involved in absorptive state -> pattern of metabolic state):
-some absorbed for protein & enzyme synthesis
-some converted to more rare amino acids for use by body cells
adipose tissue (tissue involved in absorptive state -> pattern of metabolic state):
-absorb fatty acids & glycerol from blood & triglycerides from VLDLs
-absorb glucose for ATP synthesis to drive lipogenesis
-all excess nutrients converted & stored as triglycerides
peripheral tissues (tissue involved in absorptive state -> pattern of metabolic state):
-absorb glucose for synthesis
-absorb amino acids for protein synthesis
post-absorptive state (pattern of metabolic state)
-catabolism dominates
-primary goal is to maintain glucose level to the brain
periods when there’s no more absorption from GI, cells must rely on energy reserves (post-absorptive state -> pattern of metabolic state):
-glycogen: liver & skeletal muscle (glucagon)
-triglycerides: adipose tissue
-proteins: muscle tissue (glucocorticoids)
glucagon (hormone involved in post-absorptive state -> pattern of metabolic state)
promotes release of glucose from liver
epinephrine (hormone involved in post-absorptive state -> pattern of metabolic state)
promotes release of glucose from liver, promotes lipolysis in adipose tissue & releases glycerol & fatty acids
glucocorticoids (hormone involved in post-absorptive state -> pattern of metabolic state)
inhibits use of glucose by body tissues, promotes use of fatty acids
growth hormone (hormone involved in post-absorptive state -> pattern of metabolic state)
complements glucocorticoids
liver tissue (tissue involved in post-absorptive state -> pattern of metabolic state):
-glycogenolysis to cleave glucose from glycogen & release into blood
-gluconeogenesis (glucocorticoids) to synthesize glucose from lipids
-triglyceride conversion: glycerol -> glucose & fatty acids -> acetyl -> ketone bodies
amino acid conversion (liver tissue involved in post-absorptive state -> pattern of metabolic state):
amino acids deaminated & converted to ketone bodies
ketone bodies
released into blood, absorbed by peripheral tissues, converted to acetyl & catabolized in the citirc acid cycle
ketosis
high concentration of ketone bodies will be present in all body fluids
ketoacidosis
low blood pH -> death
during starvation (post-absorptive state):
-ketosis
-oxaloacetic acid from citric acid cycle will be converted into glucose for brain
-acetyl & ketone bodies won’t be able to enter citric acid cycle
-ketones bodies build up & lead to ketoacidosis
-long-term nonfatal ketosis -> bone loss, kidney damage, heart disease
adipose tissue (tissue involved in post-absorptive state -> pattern of metabolic state)
-fat mobilization: lipolysis converts triglycerides -> glycerol + fatty acids which are released into blood
a. body cells use them for ATP synthesis
b. liver uses them for gluconeogenesis
*15-20% body fat
skeletal muscle (tissue involved in post-absorptive state -> pattern of metabolic state):
catabolism of contractile proteins, release of amino acids for use by liver in gluconeogenesis & ketone body formation
what do peripheral tissue cells do in the post-absorptive state?
lacking insulin stimulation, switch from glucose to ketone bodies for ATP synthesis
balanced diet provides:
- substrates for energy (ATP) production
- complete proteins (essential)
- essential lipids
- nitrogen (amino acids & nucleotides)
- minerals
- vitamins
minerals
inorganic ions (Ca2+, Na+)
-regulation of osmotic concentration
-physiological processes
-cofactors for enzymes
-form compunds
vitamins
organic contractors
-tissue mechanisms
-coenzymes
-antioxidants
-hormone & neurotransmitter synthesis
what vitamin does the gut bacteria synthesize?
VitK, B5, biotin
what vitamin does the skin synthesize?
VitD3
fat-soluble vitamins
- A, D, E, K
-stored in fat, too much can cause toxicity
water-soluble vitamins
- B, C, niacin, folacin, biotin
-either used or excreted by kidney
bioenergetics
study of acquisition & use of energy by organisms
-measure food in Calories
1C = 1kcal (bioenergetics)
amount of energy needed to raise temp of 1 kg H2O 1°C
-lipids -> 9.46 C/g
-carbs -> 4.18 C/g
-protein -> 4.32 C/g
metabolic rate
sum of all catabolic & anabolic reaction energy needs in body
basal metabolic rate (BMR)
minimal energy cost of living to maintain homeostasis
-measured 12hr post food, 25 °C room average
body mass index (BMI)
weight in Ib * 705 ÷ (height in inches) squared
BMI levels:
< 18 = underweight
18-25 = normal
25-30 = overweight
>30 = obese (1:3 americans)
obese
20 % + over ideal body weight
Ob mouse studies:
leptin k/o mouse = obese
-leptin release by adipocytes to trigger satiation in brain
-5% of obese people have mutation in leptin gene or leptin receptor
thermoregulation
-body temp: 97-104°F, for enzymes to function
heat: byproduct of metabolism
110°F (thermoregulation)
dead, must lose heat
radiation (heat transfer method)
infrared waves, ~50%
conduction (heat transfer method)
direct heat transfer: low %
convection (heat transfer method)
warm air rises away from skin, cold air gets heated, ~15%
evaporation (heat transfer method)
water changes to gas vapor using heat energy, ~20%, constant 10% loss due to insensible perspiration
heat regulation controlled by anterior hypothalamus:
-receptors in skin & brain detect temp change
-hypothalamus responds via ANS stimulation
too hot (thermoregulation)
-trigger heat loss
1. peripheral vasodilation (increased radiation, convection)
2. sensible perspiration (increases evaporation)
3. increased respiration depth (increases evaporation)
pyrexia
elevated temp, if too high -> heat stroke, cooling mechanisms shut down -> death
too cold (thermoregulation)
-trigger heat retention & generation
1. constrict cutaneous vessels (decreased radiation, convection)
frost bite
if the flow is restricted for too long, tissues due
non shivering thermogenesis (too cold -> frost bite)
hormones increases metabolic rate (60% of catabolism = heat)
shivering thermogenesis (too cold -> frost bite)
muscle contraction (↑ muscle metabolism & increased heat)
hypothermia
low temperature, slow metabolism, confusion
fever
triggered by pyrogens, rests thermostat, triggers heat generation to elevate body temp.
-104°F -> ok
-106°F -> dysfunctional
-110°F -> dead
heat & surface area:
-volume to surface area ratio affects heat loss & BMR
-↑ area, decreased volume = ↑ heat loss & BMR (thin people, children)
infants/small children have brown fat for heat generation (adipose with mitochondria):
aerobic respiration produces 60% heat, 40% heat
age-related changes
- ↑ non-insulin dependent diabetes (cells ignore insulin & won’t use glucose
- ↑ glucose in blood can cause permanent protein changes by binding: cataracts, glaucoma, capillary blockage -> necrosis
- ↓ metabolic rate
- ↑ malnutrition due to ↓ appetite
