Obesity Flashcards
Describe the basic principle of food homeostasis
In the hypothalamus, the arcuate nucleus is involved in food regulation. It is a circumventricular organ and thus has incomplete BBB. There are two neuronal populations that are important:
- NPY/AgrP neurones increase appetite
- POMC decrease appetite, if deficient = morbid obesity
Describe the role of leptin and what occurs if resistance
Leptin is low when body fat is low, and high when fat is high. It decreases food intake and increases thermogenesis. Activate POMC and inhibits NPY/AgrP neurones so it decreases appetite and burns fat.
Leptin circulates in blood in concentrations proportional to fat, however if leptin resistance the hormone doesn’t signal effectively. The absence of leptin causes including hyperplasia, lower energy expenditure and sterility. (No LH/FSH pulsatility)
Describe the role of insulin
Insulin circulates in plasma proportionalu to body fat. Receptors in hypothalamus - large amount of insulin reduces food intake.
Describe the different hut hormones
- Gherlin: hunger hormone, released by the stomach. There is a fatty acid on every third AA. It is activated by GOAT and high in the morning and goes down and up for lunch etc. Increases appetite by directly modulating neurones in the arcuate nucleus and thus stimulate NYP/AgrP and inhibits POMC
- PYY-36 AA: secreted by L-cells in the distal small intestine. PYY is a fullness hormone, the amount released is dependent on the size of the meal. It decreases appetite by inhibiting NPY/AgrP and stimulating POMC
- GLP-1: secreted by L cells coded by preproglucagon gene and released post-prandially. GLP-1 has incretin role and is detected and released by glucose in gut and stimulates insulin release. So reduces food intake. SAXENDA USES THIS.
Describe the reasons for obesity and the drugs tested to treat
- Thrifty gene hypothesis
- Drifts gene hypothesis.
PYY Drug but causes nausea and SAXENDA
