Pathophysiology of Obesity Flashcards

1
Q

Give two good adipokines and their function. What are they released by?

A

Both release by white fat cells (large globs of fat)

  1. Adiponectin - increase insulin sensitivity, decrease inflammation
  2. Leptin - act on neurons in the arcuate nucleus of the hypothalamus to decrease food intake
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2
Q

How do visceral and subcutaneous fat differ with respect to adipocyte size, inflammation, protective adipokines, and contribution to metabolic syndrome?

A

Visceral - large droplets, high in inflammation and low in protective adipokines, contributes greatly to DM and metabolic syndrome

SubQ fat - small droplets, low inflammation, good protective cytokines, do not contribute to DM and metabolic syndrome

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3
Q

What is the definition of obesity by waist size?

A

Men: >40”
Women: >35”

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4
Q

Why do we not see insane weight gain which is theoretically predicted with caloric excess over 30 years?

A

The BMR of the body is increased as more caories are consumed

  • > food energy becomes less efficiently used
  • > trained athletes usually have a lower BMR than coach potatoes
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5
Q

What will destruction of VM hypothalamus cause and why?

A

Cause hyperphagia and obesity - since Ventromedial thalamus is the satiety center

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6
Q

What will destruction of Lateral hypothalamus cause and why?

A

Aphagia-> anorexia and weight loss - since LH hypothalamus is the feeding center (motivation to eat)

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7
Q

What are the neurons of the arcuate nucleus of the hypothalamus which are orexigenic? Are they stimulated or inhibited by leptin? Ghrelin?

A

NPY (neuropeptide Y) + AgRP (agouti related peptide) -> stimulate hunger (orexigenic)

These are inhibited by leptin
These are stimulated by Ghrelin

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8
Q

What are the neurons of the arcuate nucleus of the hypothalamus which are anorexigenic? Are they stimulated or inhibited by leptin?

A

POMC and alpha-MSH -> inhibit hunger (anorexigenic)

These are stimulated by leptin
These are inhibited by ghrelin

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9
Q

What is the function of ghrelin? What secretes it?

A

Secreted by fundus of stomach when the stomach is empty -> stimulates appetite

Decreased ghrelin levels when stomach is full

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10
Q

What hormones secreted by the intestine / pancreas and inhibit appetite? How do they do so?

A
  1. Peptide YY
  2. GLP-1
  3. Cholecytokinin
  4. Amylin
  5. Insulin

All stimulate POMC / MSH receptors in the arcuate nucleus

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11
Q

What are the receptors for alpha-MSH in the arcuate nucleus? What happens when they are activated?

A

MC3 and MC4

When activated, like POMC neurons, the appetite is suppressed and the BMR is raised

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12
Q

What happens to those with heterozygous MC4 mutations?

A

These mutations are found in up to 2.5% of people with BMI >30 -> indicate there is a problem suppressing appetite in obesity.

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13
Q

What might MC3/MC4 agonists and antagonists be useful for?

A

Agonists - treatment of obesity

Antagonists - treatment of cachexia and anorexia

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14
Q

What is the mechanism of action of orlistat and its clinical use? Side effect?

A

Inhibits gastric and pancreatic lipase -> decreased breakdown and absorption of dietary fatty acids

Use: Obesity for weight loss

Side effect: explosive steatorrhea pg. 383

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15
Q

What drug acts as a 5-HT2C receptor agonist for weight loss? Mechanism of action after receptor binding?

A

Lorcaserin.

Stimulation of these receptors leads to POMC production -> satiety -> weight loss

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16
Q

What is the most used gastric bypass procedure?

A

Roux-en-Y -> hook up cardia of the stomach to the small intestine.