Endocrine Weight Loss Hormones and Appetite Regulation 1 — Questions and Answers
Question 1: Which hormone, primarily secreted by the stomach, is known as the 'hunger hormone' because it rises before meals?
- Leptin
- Ghrelin (Correct answer)
- Peptide YY
- Glucagon-like peptide-1
Correct answer: Ghrelin
Ghrelin, secreted by gastric X/A-like cells, rises before meals and stimulates appetite by acting on hypothalamic receptors.
Question 2: Leptin exerts its primary anti-obesity effect by acting on receptors in which brain region?
- Cerebral cortex
- Cerebellum
- Arcuate nucleus of the hypothalamus (Correct answer)
- Nucleus accumbens
Correct answer: Arcuate nucleus of the hypothalamus
Leptin acts on LepR-expressing neurons in the arcuate nucleus, particularly inhibiting NPY/AgRP neurons while activating POMC neurons to reduce food intake.
Question 3: A morbidly obese patient has very high circulating leptin levels yet continues to overeat. This phenomenon is called:
- Leptin deficiency
- Leptin resistance (Correct answer)
- Hyperleptinemia syndrome
- Ghrelin dominance
Correct answer: Leptin resistance
Leptin resistance occurs when the brain fails to respond appropriately to elevated leptin signals, a hallmark of obesity that perpetuates further weight gain.
Question 4: Peptide YY (PYY) is released by L-cells in the distal gut in response to food intake and primarily acts to:
- Stimulate appetite and increase gastric motility
- Inhibit appetite and slow gastric emptying (Correct answer)
- Stimulate insulin secretion from beta cells
- Increase glucagon release from alpha cells
Correct answer: Inhibit appetite and slow gastric emptying
PYY is a satiety hormone that inhibits food intake by acting on hypothalamic Y2 receptors and slows gastric emptying to promote fullness.
Question 5: Which neuropeptides in the arcuate nucleus are classified as orexigenic (appetite-stimulating)?
- POMC and CART
- NPY and AgRP (Correct answer)
- Alpha-MSH and BDNF
- CRH and TRH
Correct answer: NPY and AgRP
Neuropeptide Y (NPY) and agouti-related protein (AgRP) are potent orexigenic signals that increase food intake and decrease energy expenditure.
Question 6: GLP-1 receptor agonists used for weight loss (e.g., semaglutide) promote satiety primarily through which mechanism?
- Blocking ghrelin receptors in the stomach
- Activating GLP-1 receptors in the hypothalamus and delaying gastric emptying (Correct answer)
- Inhibiting reuptake of serotonin and norepinephrine
- Blocking cannabinoid CB1 receptors
Correct answer: Activating GLP-1 receptors in the hypothalamus and delaying gastric emptying
GLP-1 receptor agonists reduce appetite by activating hypothalamic GLP-1 receptors and also slow gastric emptying, both of which enhance satiety.
Endocrine Weight Loss Hormones and Appetite Regulation 1
Which hormone, primarily secreted by the stomach, is known as the 'hunger hormone' because it rises before meals?