Final answer:
The correct analogy that matches the function of fat cells with that of the digestive tract by comparing satiety and hunger hormones is 'b. PYY is to ghrelin', as both PYY and leptin are associated with reducing appetite, whereas ghrelin stimulates it.
Step-by-step explanation:
The analogy 'fat cells are to the digestive tract' compares the function of fat cells in producing satiety hormones to the role of the digestive tract in the production or response to appetite hormones. Here's a breakdown of the options provided:
- Leptin is a hormone produced by adipose tissue (fat cells) that signals satiety and helps to regulate energy balance by inhibiting hunger, which in turn diminishes fat storage in adipocytes.
- Orexin, also known as hypocretin, is a neurotransmitter that regulates arousal, wakefulness, and appetite.
- PYY, or peptide YY, is a hormone produced by the gut in response to eating and has been found to reduce appetite.
- Ghrelin is a hormone produced in the stomach that stimulates appetite, increasing food intake and promoting fat storage.
The correct analogy that matches the function of fat cells with that of the digestive tract by comparing satiety and appetite hormones is 'b. PYY is to ghrelin'. This is because PYY is produced by the digestive tract and inhibits appetite, similar to how leptin is produced by fat cells and inhibits appetite. Ghrelin, on the other hand, stimulates appetite, making it dissimilar to the effects of leptin and PYY.