Obesity Flashcards
What is the result of metabolic stress?
metabolic syndrome central obesity dyslipidemia insulin resistance T2DM CVD
How do you calculate BMI?
weight/height2
What are the ranges of BMI?
up 25 - healthy
25-29.9 - overweight
30-39.9 - obese
>40 - morbidly obese
What are the major factors influencing obesity?
genetics
environment
What are the major contributers to disease and premature mortality?
T2DM high BP heart attack certain cancers osteoarthritis
When is the risk of T2DM increased?
BMI of over 30
What are the potential consequences of diabetes?
stroke respiratory disease heart diease gall bladder disease osteoarthritis dementia NAFLD diabetes cancer hyperuricemia gout
Why do we need fat?
energy storage
prevention of starvation
energy buffer during illness
What are the CNS influences on energy balance and body weight?
Behaviour - feeding and physical activity
ANS activity - regulates energy expenditure
Neuroendocrine system - secretion of hormones
What is the neural centre responsible for energy intake?
hypothalamus
What lesions induce leanness and obesity?
ventromedial hypothalamus - obesity
lateral hypothalamus - leanness
What are the satiation signals?
signals that increase during a meal to limit meal size
What are the satiation signals and where do they come from in the GI tract?
CCK - enteroendocrine cells -> nucleus of solitary tract in hind brain
PYY - mucosal L cells -> hypothalamus
GLP-1 - released form L cells -> Hypo and NTS
OXM - oxyntic cells of sm. intestine
Obestatine - cells lining stomach and sm.intestine
What is the effect of PYY?
inhibits gastric motility, slows emptying and reduces food intake
What is the effect of GLP-1?
inhibits gastric emptying and reduces food intake
What is the effect of OXM?
inhibits appetite
What is the effect of Obestatin?
reduces food intake
What is the effect of Obestatin?
reduces food intake
Where is ghrelin produced?
oxyntic cells of the stomach
What stimulates ghrelin?
fasting and hypoglycaemia
What is adaptive thermogenesis?
increasing energy expenditure by uncoupling oxidative metabolism from ATP production
What is the key protein in adaptive thermogenesis?
UCP1
How is UCP1 activated?
fatty acids
What does UCP1 do?
short circuits the proton gradient in the mitochondria to accelerate fuel oxidation and produce heat
What long-term appetite controllers stimulate food intake?
glutamate, gaba and opioids
What long-term appetite controllers inhibit food intake?
monoamines
What two hormones produced in peripheral tissues act on the hypothalamic neurons?
insulin and leptin
Where is leptin made and release?
fat cells
What do leptin and insulin communicate to the brain?
fat status - as fat increases do they
tell brain to eat less and burn more
What is the Ob/Ob mouse mutation?
inability to produce leptin
What is the Ob/Ob mouse mutation?
inability to produce leptin
What does reduced leptin induce?
starvation response which causes unrestrained appetite
What are the signs of the Ob/Ob mouse?
hyperphagia, reduced energy expenditure, hyperglycaemia, hyperinsulinemia
How can you rescue the Ob mouse?
administering leptin
What is different in the db/db mouse?
it has an leptin insensitive receptor
What are the signs of the db/db mouse?
hyperglycemic, hyperinsulinemic, insulin resistant
Where are there high levels of leptin receptor?
arcuate nucleus in the hypothalamus
What are the biological roles of leptin?
food intake and energy expenditure angiogenesis tumourigenesis bone formation maintenance of reproductive system maintenance of immune system peripheral glucose homeostasis
What are the roles of insulin?
inhibits food intake
circulates in proportion to body adiposity
