SM_146b: Appetite Regulation and Energy Expenditure Flashcards
Conservation of energy: ____ - ____ = ____
Conservation of energy: energy in - energy out = change in body weight
Body fat is generally ____
Body fat is generally stable
Resting metabolic rate contributes ___ of total energy expenditure
Resting metabolic rate contributes 65% of total energy expenditure
Energy homeostasis is ____
Energy homeostasis is the biological process through which energy intake and expenditure are matched to one another so as to promote stability in the amount of fuel stored as fat
Fat stores are increased in ____, ____, and ____
Fat stores are increased in growth and development, pregnancy, and recovery from illness
Components of energy expenditure include ____, ____, and ____
Components of energy expenditure include basal metabolic rate (65%), thermic effect of food (10%), and physical activity level (25%)
Total energy expenditure = BMR + TEF + PAL
____ is the rate of energy expenditure which is required at complete rest for all cellular function to maintain body systems and regulate body temperature
Basal metabolic rate is the rate of energy expenditure which is required at complete rest for all cellular function to maintain body systems and regulate body temperature
____ is the amount of energy expenditure above basal metabolic rate due to the cost of processing food for use and storage
Thermic effect of food is the amount of energy expenditure above basal metabolic rate due to the cost of processing food for use and storage
Brain mechanisms modulate sensory factors by satiety signals to produce ___ and ___
Brain mechanisms modulate sensory factors by satiety signals to produce reward value and appetite
- Satiety / hunger signals: fat cell hormones, gut hormones, and gastric distention
____ governs day-to-day energy intake
Ghrelin governs day-to-day energy intake
Describe gut peptides that regulate appetite and gut hormones that are released by nutrient sensing cells in the intestine
Gut peptides that regulate appetite and gut hormones that are released by nutrient sensing cells in the intestine
____ is the only orexigenic gut hormone
Ghrelin is the only orexigenic gut hormone
- Acts as a neurotransmitter, expressed within the ARC and periventricular area of hypothalamus
- Levels of circulating ghrelin have been noted to increase before meals and fall rapidly after eating
- Both CNS and peripheral administration of ghrelin increases food intake and body weight with a reduction in fat utilization in rodents
- Fasting plasma levels are high in patients with anorexia nervosa and in subjects with diet-induced weight loss
____ signals hunger
Ghrelin signals hunger
Ghrelin ____ after weight loss
Ghrelin increasesafter weight loss
Desire to eat ____ after weight loss
Desire to eat increases after weight loss
____ stimulates appetite, while ____ and signal satiety
Ghrelin stimulates appetite, while GLP-1 and PYY and signal satiety
- Meal-to-meal and day-to-day energy regulation is primarily governed by gut hormones
- Weight loss is associated with metabolic regulation in gut hormones that are intended to drive energy stores back to initial replete levels
___ is involved in long-term adipose signals for energy regulartion
Leptin is involved in long-term adipose signals for energy regulartion
Amount of ____ produced by fat tissue directly correlates with adipose tissue mass and mRNA expressed in this tissue
Amount of leptin produced by fat tissue directly correlates with adipose tissue mass and mRNA expressed in this tissue
Leptin increases more as BMI increases in ___
Leptin increases more as BMI increases in females
___ senses adequate or healthy amount of body fat
Hypothalamus senses adequate or healthy amount of body fat
Congenital leptin deficiency is associated with ____
Congenital leptin deficiency is associated with massive weight gain
Obesity is associated with ____
Obesity is associated with leptin resistance
- CNS levels do not rise proportionately due to saturation of the leptin receptor and reduced intracellular signaling despite elevated secretion and circulation of leptin in obesity
- CNS does not properly sense expanded adipose mass
Leptin is reduced in response to ____, ____, and ____
Leptin is reduced in response to reduction in calories, weight loss, and increasing appetite
- Leptin levels remain below baseline -> signal to brain that the energy (fat) reserve is low
Summarize adipose signaling
Adipose signaling
- Week-to-week energy regulation is primarily governed by leptin which is produced in adipocytes
- Leptin informs the CNS of the amount of energy (fat) stored in the body
- Leptin system is more effective in signaling depletion of energy stores (weight loss) and less effective in signaling energy surplus (excess body fat)
____ and ____ are orexigenic neuropeptide
NPY and AgRP are orexigenic neuropeptide
- Neuropeptide Y
- Agouti-related protein
____ and ____ stimulate food intake in the ____
NPY and AgRP stimulate food intake in the hypothalamic arcuate nucleus
____ and ____ suppress food intake in the ____
POMC and CART suppress food intake in the hypothalamic arcuate nucleus
- POMC: proopiomelanocortin
- CART: cocaine- and amphetamine-regulated transcript
Describe the action of leptin in the arcuate nucleus
Action of leptin in the arcuate nucleus
- Leptin inhibits NPY/AgRP neurons acting on its receptors and
- Decrease in the release of the inhibitory transmitter GABA
- POMC neurons are free of inhibition
- POMC increase their firing rate
- Alpha MSH produced (inhibitor of appetite)
(leptin also acts directly on the POMC neurons)
____ is when injury or lesions in the hypothalamus may result in a pattern of weight gain that is characterized as abrupt in onset and rapidly accelerating
Hypothalamic obesity is when injury or lesions in the hypothalamus may result in a pattern of weight gain that is characterized as abrupt in onset and rapidly accelerating
In the hypothalamic response to a high fat diet, _____
In the hypothalamic response to a high fat diet, inflammation may reduce responsiveness to normal neuropeptide signaling
____ controls appetite and metabolism
Hypothalamus controls appetite and metabolism
- 6% of children with severe obesity have a mutation in the MC4 receptor
- 3% of subjects with severe early onset obesity have a LEPR mutations
Homeostatic pathways that regulate eating include ____, ____, and ____
Homeostatic pathways that regulate eating include the paraventricular nucleus, arcuate nucleus, and lateral hypothalamic nucleus
Reward pathways that regulate eating include ____ and ____
Reward pathways that regulate eating include dorsal striatum / nucleus accumbens and substantia nigra / ventral tegmental area
____ and ____ are activated by hunger
Left and right amygdala and medial orbitofrontal cortex are activated by hunger
(decreased activation by fullness)
Summarize CNS regulation of appetite
CNS regulation of appetite
- Appetite regulation and energy baalnce is governed by a yin-yang system of neuropeptides
- POMC/CART are anorexigenic while NPY/AgRP are orexigenic
- Orexigenic pathways predominate
- Gut peptides and leptin mediate the relative release of primary neuropeptides, maintaining the energy balance of homeostasis
- Hedonic reward pathway is responsible for food seeking behavior which overrides the homeostatic pathway
