Ch 12 - Bioenergetics, Metabolic Regulation Flashcards

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1
Q

Gibbs free energy equation

A

deltaG = deltaH - T*deltaS

  • negative deltaG is spontaneous
  • deltaG = deltaGo + RT ln(Q)
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2
Q

Energy derived from fat and carbs

A
  • protein = 4 kcal/g
  • carbs = 4 kcal/g
  • ketones = 4 kcal/g
  • fat = 9 kcal/g
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3
Q

ATP

A
  • adenosine triphospahte
  • formed via substrate level phosphorylation or oxidative phosphorylation
  • provides about 30 kJ/mol
  • used due to high energy phosphate bonds
  • ADP is stable by resonance
    • ATP is less stable
    • hydrolysis to AMP is also spontaneous
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4
Q

ATP coupled reactions

A
  • ATP cleavage and transfer phosphate group to another molecule
  • activate or inactive other molecule
  • phosphoryl group transfers
  • coupled with unfavorable reaction
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5
Q

high energy electron carriers

A
  • NADH
  • NADPH
  • FADH2
  • ubiquinone
  • cytochromes
  • glutathione
  • proteins with iron-sulfur clusters are good electron transporters
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6
Q

Flavoproteins

A
  • have modified vitamin B2
    • aka riboflavin
  • nucleic acid derivatives
    • FAD - flavin adenine dinucleotide
    • FMN - falvin mononucleotide
  • in mitochondria and chloroplasts as electron carriers
  • coenzymes fro oxidation of fatty acids
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7
Q

Postprandial state

A
  • absorptive or well fed state
  • greater anabolism
  • nutrients into gut and hepatic portal to the liver
  • lasts 3-5 hrs after eating
  • blood glucose rises and stimulate insulin release
  • insulin targets liver, muscles, adipose tissue
  • promote glycogen synthesis
  • excess glucose converted to fatty acid and triglycerols
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8
Q

Insensitivity to Glucose (special cells)

A
  • nerve cells - oxidize glucose to CO2, insentitive to insulin
  • RBC - use glucose anaerobically
    • insensitive to insulin
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9
Q

Fasting State

A
  • postabsorptive state
  • counterregulatory hormones - oppose insulin
    • glucagon, cortisol, epi, norepi, GH
  • stimulate glucogenolysis in liver
  • stimulate hepatic gluconeogenesis
    • slower than glucogenolysis
  • release amino acids from skeletal muscle
  • release fatty acids from adipose tissue
  • Amino acids and fatty acids carried to liver for gluconeogenesis
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10
Q

Starvation

A
  • prolonged fasting
  • high glucagon and epi
  • rapid degradation of glycogen in liver
  • gluconeogenesis maintains glucose levels
  • excess acetyl-CoA from lipolysis is used for ketone bodies
  • Muscles use fatty acids
  • Brain uses ketones
  • RBC still use glucose
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11
Q

Insulin

A
  • peptide hormone
  • made by Beta cells in pancreatic islets of Langerhans
  • required by adipose and skeletal muscle to uptake sugar (glucose transporters)
  • increases metabolism of carbs
  • increase glycogen synthesis in liver
  • increase amino acid uptake by muscles
  • increase triclygerol uptake by fat cells
  • directly controlled by plasma glucose level
    • glucose enters beta cell, metabolized, increase intracellular ATP, Ca2+ release, exocytosis
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12
Q

Insulin resistant cells

A
  • nervous tissue
  • kidney tubules
  • intestinal mucosa
  • RBC
  • beta cells of pancreas
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13
Q

Glucagon

A
  • peptide hormone
  • alpha-cells of pancreatic islets of Langerhans
  • targets hepatocytes via second messenger
  • increase liver glycogenolysis
  • increase liver gluconeogenesis
  • increase liver ketogenesis
  • increase lipolysis in the liver
  • promoted by low plasma glucose
  • basic amino acids promote secretion
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14
Q

Glucocorticoids

A
  • from adrenal cortex
  • Cortisol - secreted during stress
  • promotes use of energy stores
  • elevates blood glucose
  • inhibit glucose uptake in most tissues - to increase availability in brain
  • Increase hepatic output and gluconeogenesis
  • enhance glucagon, epi, catecholamines
  • long term causes hyperglycemia
    • stimulate insulin
    • promote fat storage
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15
Q

Catecholamines

A
  • secreted by adrenal medulla
  • epi and norepi
  • increase liver and muscle glycogen phosphorylase - glycogenolysis
    • increase glucose output from liver
  • increase glycogenolysis in skeletal muscle
    • lacks enzymes, therefore does not reach bloodstream and is metabolized by muscle cells
  • increase lipolysis via increase lipase
  • increase BMR
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16
Q

Thyroid Hormones

A
  • Kept relatively constant
  • increase basal metabolic rate (BMR)
  • thyroxine (T4) - latent effect that is longer lasting
  • triiodothyronine (T3) - shorter rapid effect
  • deiodonases convert T4 to T3
  • effect lipid and carb metabolism - increase absorption from small intestine and clearance of cholesterol
17
Q

Liver metabolic source

A

well fed - glucose and amino acids (primary)

fasting - fatty acids

18
Q

Skeletal muscle (resting) metabolism

A

well fed - glucose

fasting - fatty acids and ketones

19
Q

cardiac muscle metabolism

A

well fed - fatty acids

fasting - fatty acids and ketones

20
Q

adipose tissue metabolism

A

well fed - glucose

fasting - fatty acids

21
Q

brain metabolism

A

well fed - glucose

fasting - glucose

prolonged - ketones

22
Q

RBC metabolism

A

well fed - glucose

fasting - glucose

23
Q

Role of liver in metabolism

A
  • maintain constant blood glucose level
  • synthesize ketones
  • glycogenosis
    • carbon source - lactate, glycerol, amino acids
  • excess glucose into fatty acids via Acetyl CoA
  • fatty acids into blood via very low density lipoproteins (VLDL)
24
Q

Adipose tissue role in metabolism

A
  • insulin causes glucose uptake
  • insulin triggers fatty acid release from VLDV and chylomicrons
  • lipoprotein lipase induced by insulin
    • fatty acids released are reesterified to triglycerols
  • hormone-sensitive lipase - epi activated due to low insulin
    • fatty acids into circulation
25
Q

Skeletal Muscle role in metabolism

A
  • resting muscle - uses glucose and fatty acids
    • induced by insulin to uptake glucose
      • replenish glycogen and amino acids
    • use fatty acids found in blood
    • can use ketone bodies in prolonged fasting
  • active muscle -
    • creatine phosphate - short lived (2-7 seconds)
      • transfer phosphate to ADP to make ATP
    • anaerobic glycolysis - uses stored glycogen
    • continuous exercise - oxidation fo glucose and fatty acids
26
Q

Brain role in metabolism

A
  • glucose as primary source
  • brain release glucagon and epi when blood glucose low
  • fatty acids cannot cross BBB - not direct energy source
    • can use ketones that are produced else where
  • glucose from hepatic glycogenolysis or gluconeogenesis
27
Q

Respirometry

A
  • used to measure the respiratory quotient
  • RQ = CO2 produced / O2 consumed
    • higher RQ for carbohydrates than lipids
28
Q

Regulation of body mass

A
  • water for minor weight flucuations
  • lipids for gradual change in body mass over time
  • effected by diet, exercise genetics, SES, geography
29
Q

Hunger and Satiety Hormones

A
  • Ghrelin - secreted by stomach, signaled by anticipation of a meal (smell, sound)
  • Orexin - stimulated by ghrelin
    • increase appetite
    • affects alertness and sleep-wake cycle
  • Leptin - decreases appetite
    • supresses orexin
30
Q

BMI

A

Body mass index

BMI = mass/height2