Ch. 12: Bioenergetics & Regulation of Metabolism Flashcards
what kind of systems are biological systems
open systems
can exchange energy and matter with the environment
what is the quantity of interest when determining changes of internal energy for living systems
heat
pressure and volume of living systems remains constant
what kinds of reactions have negative deltaG
spontaneous rxns in the forward direction, net loss of free energy
what kinds of reactions have positive deltaG
non spontaneous rxns, net gain of energy
when is deltaG zero
as the reaction approaches equilibrium
what are conditions in the modified standard state
[H+] = 10^-7 and pH = 7
delta G —> delta G’
@ 1M most con’c of protons would have pH 0
why is ATP a good energy carrier
high energy phosphate bonds
where is ATP produced
MOST –> ATP synthase in the mitochondria
SOME –> glycolysis and citric acid cycle
common involvement of ATP in coupled reactions
ATP hydrolysis
unfavorable movement across one gradient (like Na+ and K+) is coupled with the release of energy from ATP Hydrolysis
what occurs during ATP cleavage
high-energy phosphate group is transferred from ATP to another molecule, generally activating/inactivating the large molecule in a phosphoryl group transfer
what are high-energy electron carriers
NADH, NADPH, FADH2, ubiquinone, cytochromes, glutathione
what are flavoproteins
nucleic acid derivatives that contain a modified vitamin B12 and function as
- electron carriers in the mitochondria
- vitamin B activators
- coenzymes for fatty acid oxidation, pyruvate decarboxylation, and glutathione reduction
what is homeostasis
physiological tendency toward a stable state that is maintained and adjusted, often with the expenditure of energy
what is the difference between homeostasis and equilibrium
equilibrium is fixed and does not allow for storage or mobilization … not desirable in a constantly changing external environment
when is the postprandial state occur
absorptive/well-fed state
occurs shortly after eating
- –> greater anabolism (biomolecule synthesis) and food storage
- –> nutrients to gut, liver, stored or distributed
- –> blood glucose increase, insulin increase
what does insulin promote
glucose increase, insulin increase
- glycogen synthesis in liver and muscle (until filled)
- –> then liver converts excess to fatty acids/triacylglycerols
- glucose entry + triacylglycerol synthesis in adipose
- glucose entry + protein synthesis in muscle
what cell types are insensitive to insulin
red blood cells (use glucose anaerobically regardless of metabolic state) nervous system (oxidize glucose to CO2 and H2O regardless of metabolic state)
what are counterregulatory hormones
hormones that oppose the actions of insulin
glucagon, cortisol, epinephrine, norepinephrine, growth hormone
when does the post absorptive state occur
fasting state
- glucagon stimulates glycogen degradation in the liver releases glucose into the blood (5+ hours after eating)
- glucagon stimulates hepatic gluconeogenesis (12+ hours after eating)
- epinephrine stimulates amino acid (muscle) and fatty acid (adipose) release, transport to liver, and transformation for gluconeogenesis
when doe the prolonged fasting state occur
starvation, 24+ hours
- high levels glucagon and epinephrine
- –> glycogen stores depleted
- –> rapid lipolysis –> acetyl coA –> ketone bodies –> brain
- –> gluconeogenic activity
what kind of hormone is insulin
peptide hormone, water soluble
how does insulin (and other hormones) regulate metabolism across the entire organism
peptide hormone –> rapidly adjust metabolic processes via second messenger cascades
what cells secrete insulin
beta cells in the pancreas
what tissues do not alter glucose uptake in response to insulin
- nervous tissue
- kidney tubules
- intestinal mucosa
- red blood cells
- beta cells of the pancreas
what is the primary controller of insulin secretion
plasma glucose (high levels activate, low levels deactivate)
what cells secrete glucagon
alpha cells in the pancreas
what is the primary target of glucagon
hepatocytes
- -> increases glycogenolysis
- -> increases gluconeogeneis
- -> increases liver ketogeneis, decreased lipogenesis
- -> increased lipolysis
what is the primary controller of glucagon secretion
plasma glucose (low levels activate, high levels deactivate)
why are glucocorticoids part of the stress response
glucose must rapidly be mobilized during a stress response
what are catecholamines
epinephrine (adrenaline) norepinephrine (noradrenaline)
- increase metabolic function associated with an adrenaline rush
thyroid hormones influence the metabolism of what molecules
lipids and carbohydrates
how do thyroid hormone levels fluctuate with metabolic state
thyroid hormones levels are relatively constant regardless of metabolic state, have long acting effects
what fuel does the liver use
well fed: glucose and amino acid
fasting: fatty acids
what fuel does the rising skeletal muscle use
well fed: glucose
fasting: fatty acids, ketones
what fuel doe the cardiac muscle use
well fed: fatty acids
fasting: fatty acids, ketones
what fuel does the adipose tissue use
well fed: glucose
fasting: fatty acids
what fuel does the brain use
well fed: glucose
fasting: glucose (ketones in prolonged fast)
what fuel do red blood cells use
well fed: glucose
fasting: glucose
what are the major roles of the liver in metabolism
- maintain constant level of blood glucose
- synthesize ketones when fatty acids are oxidized
how are mass and basal metabolic rate related
directly proportional with mass being the dependent factor
when mass increases, rate increases
what hormones increase appetite
gherkin and orexin
what hormones increase satiety
leptin
