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11 Cards in this Set
- Front
- Back
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cellular sensors for nutrient depletion |
-AMP kinase system: sense intractellular AMP/ATP ratio; promote catabolism -GCN2 pathway: senses essential AA deficiency; GCN2 binds unbound tRNAs, and phosphorylates and deactivates protein synthesis |
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cellular sensors for adequate nutrient availability |
-mTORC system: mTORC1 is activated by many different nutrients (primarily AAs) and growth factors through convoluted pathways (e.g. utilizes tuberous sclerosis proteins), and leads to proliferation, mitochondrial biogenetics, and cell cycle progression |
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cellular sensors for stress and nutrient excess |
-UPR system: aka unfolded protein response; too much increase in protein synthesis leads to ER stress, which causes unfolded proteins, which is sensed and results in increased antioxidant synthesis, increased inflammatory gene, decreased protein synthesis, increased triglyceride synthesis, and increased chaperone synthesis |
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cellular integrator of nutrient balance |
-located in the medial-basal hypopthalamus -serves as a setpoint comparator, which can be reset many times in a lifetime -senses nutrients in the plasma through all the cellular mechanisms (mTOR, AMP kinase, UPR, etc), -senses glycogen and fat stores and calories in GI tract through neuronal and hormonal signals -regulates food intake and efficiency of fuel and ATP use |
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neuronal and hormonal signals that indicate nutrient depletion |
-orexigenic peptides from GI tract: ghrelin -neuronal through the NTS |
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neuronal and hormonal signals that indicate nutrient stores |
-anorexigenic peptides from the GI tract: CCK, GLP-1, enterostatin -leptin is secreted in proportion to adipose tissue stores and inhibits food intake -neuronal signals from the liver |
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alpha MSH neuronal pathway |
-inhibits food intake and stimulates ATP use via MCR4 receptor -activated by leptin |
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NPY neuronal pathway |
-inhibits output neurons that inhibit food intake and stimulate ATP use -activated in response to orexigenic peptides, specifically ghrelin |
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leptin |
-released in proportion to adipose tissue stores -encourages the use of calories -tells hypothalamus to reduce food intake, and the pituitary to increase hormone secretion; promotes FFA oxidation and inhibits GIIS -inhibits the ghrelin inhibitory pathway |
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ghrelin |
-activates NPY, which inhibit output neurons of the hypothalamus, which ordinarily inhibit food intake and increase energy expenditure -released from GI tract?/? |
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cortical pathways |
-can override hypothalamus signals -recall that hypothalamus is surrounded by limbic and cortical system -thus food intake is influenced by the nature of the diet (sweetness and increased lipid content) -energy expenditure is regulated by exercise, efficiency of energy use, and efficiency of ATP production |
