4_2WeightRegulation Flashcards
What is the law of conservation of energy?
the total energy of an isolated system is constant
What components affect “calories in”?
consumption and energy extraction
What is energy extraction?
the capacity to extract calories from food (variable among patients; microbes may play role)
What factors affect “calories out”?
1) BMR, 2) physical activity, 3) tissue repair, 4) thermogenesis
RQ equation
RQ = CO2 produced / O2 produced
RQ of carb
1
RQ of protein
0.8
RQ of fat
0.7
What are the components of adaptive thermogenesis?
1) cold-induced shivering, 2) cold-induced non-shivering; 3) diet-induced
What are the components of Total Energy Loss?
Adaptive Thermogenesis + 1) BMR, 2) thermic effect of food, 3) thermic effect of exercise
What is actual energy used?
total energy loss + physical activity, growth, reproduction
How is BMR regulated?
1) primarily TH, 2) Leptin, 3) GH/insulin, 4) SNS/PNS, 5) thermoregulation via shivering and cytokines for fever
How is shivering activated?
sensory neurons in skin go to HT, the primary shivering motor center
Define hunger.
physiological need for food or specific nutrient
Define appetite
psychological desire for food
Define orexigenic
appetite stimulant
Define anorexigenic
appetite suppressant
Define satiety
state of satisfaction
What is the RER?
resting energy ratio, which is approxiately equal to RQ
What is the purpose of the RER?
reflective of fuel utilization
Which nutrient is preferentially stored and why?
lipids - efficiency
How many kilocalories = 1 pound?
3500
How can resistance to diet-induced obesity be caused?
1) transdifferentiation/beiging, 2) impact mitochondrial function, 3) enhance UCP protein leaks, 4) also, satiety (not metabolic)
GLP-1 impact on satiety
ANorexigenic
CCK impact on satiety
ANorexigenic
PYY impact on satiety
ANorexigenic: inhibits orexigenic neurons
Leptin impact on satiety
ANorexigenic: works on orexigenic and anorexigenic neurons
Insulin impact on satiety
ANorexigenic: stimulates anorexigenic neurons
Ghrelin impact on satiety
Orexigenic: stimulates orexigenic neurons
Where do neuroendocrine satiety factors stimulate an/orexigenic neurons?
in the arcuate nucleus of the hypothalamus
Where are 2nd order neurons of the neuroendocrine adipose-gut axis located?
PVN of hypothalamus
Where is the satiety center?
nucleus tractus solitarius
What protein products do the orexigenic neurons contain?
AgRP and NPY
What protein products do the anorexigenic neurons contain?
POMC and CART
Where is ghrelin released?
the EMPTY stomach
Where is PYY released?
small intestine
How do leptin and the neuro-endocrine gut factors differ?
leptin is long term; others are short-term
Where do the gut factors stimulate in addition to the arcuate nucleus?
Vagus nerve, which projects to the brainstem. Brainstem connects with PVN and NTS
What roles do the gut flora play in obesity?
1) induce tissue change, 2) influence extraction
How do gut flora induce tissue change?
affect beta-oxidation, inflammation (LPS), lipogenesis, incretin secretion, and butyrate production; sum of effects is to change insulin sensitivity
What factors of gut flora improve insulin sensitivity?
butyrate production from large intestine, incretin secretion from epithelium
What factors of gut flora decrease insulin sensitivity?
LPS from adipose, short chain fatty acids from liver that cause lipogenesis, FIAF/AMPK in muscle that cause fatty acid oxidation
