Obesity & thermogenesis Flashcards
1
Q
What is the role of brown adipose tissue (BAT)?
A
- Triggers non shivering thermogenesis.
- Associated with lower fasting plasma glucose.
- Important role in homeostasis.
- Controlled by sympathetic system.
- Recieves high blood flow when active & has overactive glucose uptake capacity.
2
Q
How does the sympathetic system control BAT?
A
- Sympathetic system branches get activate and innervate BAT and release norepinephrine (NE).
- NE stimulates degradation of trigylcerides and free fatty acids are combusted in mitochondria to produce heat do to uncoupled proteins.
- Glucose uptake is stimulated and combusted which demands a lot of oxygen from the blood.
- Blood is oxygen depleted after leaving BAT and heat is rapidly transported out of the body by the blood.
3
Q
How can diet-induced thermogenesis occur (DIT)?
A
- Achieved by uncoupling of ATP synthesis and proton transport across mitochindrial membrane in BAT.
- Simulated by sympathetic innervation causing upregulation of mitochondrial uncoupling protein.
4
Q
What are the reasons newly born children can be obese?
A
- May involve hormones, nutrients and inflammatory cytokines produced by the overnourished pregnant mother.
- Development of neural circuitry that regulates energy balance can be affected.
5
Q
How does orlistat work?
A
- Binds irreversibly to active sites of lipase through covalent bonding.
- Reduces a third of trigylceride intake through GI absorption.
- Limited but significant impact on weight.
6
Q
Why use metformin?
A
- Hypoglycemic agent which is an insulin sensitiser.
- Well tolerated, good effect on weight.
- Works well in childhood obesity.
7
Q
Why use GLP-1analogues?
A
- Potentiate insulin release and decrease glucagon release.
- Has significant effect on food intake, produced weight loss but at a higher dose than required for glycemic control.
8
Q
Why use sibutramine?
A
- Decreases food intake by increasing meal-induced satiety.
- Has weak thermogenic effects.
- Well tolerated but may cause hypertension.
9
Q
Why use rimonabant?
A
- Novel agents which blocks CB1 receptors which stimulates hunger centres in the hypothalamus.
- Reduces appetite and promotes weight loss.
- Stimulates adiponectin release, good CVD effect.
10
Q
What is an alternative to medication?
A
Bariatric surgery:
- Creation of a small gastric pouch.
- Small intestine is divided which transposts gastric secretions to the pouch.
- Common channel is produced where digestive enzymes mix with ingested food.
