Obesity and regulation of appetite Flashcards
What is overweight BMI?
25-29.9
What BMI is associated with obesity?
greater than 30
What waist circumference in men and women is associated with high risk of obesity?
greater than 40/35 inches
What is the significance of waist circumference
indirect measure of central adiposity correlated with visceral fat. Excess fat in the abdomen is an independent predictor of risk factors and morbidity.
What 3 factors influence intake and expenditure?
enviornmental and social influences, genetic makeup, individual choices
Of the 3 components that comprise energy expenditure, what has the greatest impact?
basal metabolic rate (others are physical activity, thermic effect of food)
What are afferent signals that increase appetite?
NE, neuropeptide Y, agouti-related peptide, ghrelin
What are afferent signals that decrease appetite?
leptin, insulin, a-melanocyte-stimulating hormone)
Afferent signals that increase appetite and those that decrease appetitie are recieved in the _____
hypothalamus, (lateral)
What 5 things make up TEE? (total energy expenditure
- REE: resting energy expenditure
- TEF: thermic effect of food
- ADL: activities of daily living
- exercise
- NEAT: non-exercise activity thermogenesis
_____ integrates diverse signals like appetite and sends efferent signals to regulated energy intake and expenditure
Hypothalamus (lateral)
What signals does the hypothalamus secrete that STIMULATE food intake?
NPY, AgRP, hypocretins, orexins
T or F AgRP is short lived.
False. one injection can last several days. NPY is short lived
How is the appetite stimulating effect of AgRP mediated?
Antagonism of MC3 and MC4. This reverses inhibition of food intake induced by alpha-MSH
What hormones released by the hypothalamus to stimulate food intake may also have a role in sleep?
hypocretins and orexins
What 2 receptors are part of the ECS? What do they do?
CB1: CNS,GI tract, adipocytes. increase appetite, motivation to eat, fat accumulation, intereferes with feelings of satiety
CB2: no role in appetite regulation
What ANOREXIGENIC agents are released by the hypothalamus
CART, serotonin, melanocortins (act on MC4 receptors)
What adipocyte-derived signals play a role in regulation of food uptake?
TNFa: insulin resistance
adiponectin: deficient in obese pt
Leptin: absence leads to overfeeding and massive obesity, inhibits NPY actions
What pancreatic signals play a role in regulation of food intake
Insulin: deficiency/resistance associated with hyperphagia. Role in satiety and meal termination
PP: Satiety signaling and reduction of food intake
What GI signals play a role in food intake
Ghrelin: stimulates GH secretion, increased food intake
PYY: satiety signal
GLP1: gut-derived satiety signal, suppress glucagon secretion
Cholecystokinin: potent satiety signal
What are incretins?
GLP1 and GIP….. boost postprandial insulin secretion
______ is the only peripheral signal activated preprandially and may be unique in its role as a rare peripheral signal for hunger and meal initiation.
Ghrelin
_____ is the most common known monogenic obesity factor.
MC4R
Describe the pathogenesis involved in MC4R mutations
a-MSH on MC4R causes decreased food intake. Mutation–> hyperphagia.
Clinical manifestations: increased linear growth, increased fat and lean body mass, increased bone mineral density, severe hyperinsulinemia
What does leptin therapy induce?
weight loss
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