The conversion of ammonia (NH3) to nitrites (NO2-) and then to nitrates (NO3-) by bacteria is called: MCQ with Answer and Explanation

Explanation:
Vasoactive Intestinal Peptide (VIP) is a 28-amino acid neuropeptide that acts as a neurotransmitter and a hormone. In the gastrointestinal tract, its primary functions are stimulatory and relaxant: it stimulates the secretion of water and electrolytes into the intestinal lumen (acting as a secretagogue), relaxes the smooth muscle of the gut (including the lower esophageal sphincter, stomach, and gall bladder), and stimulates the pancreas to secrete a bicarbonate-rich juice. It also causes vasodilation in the gut. Excessive VIP secretion can lead to severe watery diarrhea (as in VIPoma).

Explanation:
Neurotensin is a 13-amino acid peptide that functions as both a neuromodulator in the central nervous system and a hormone in the gastrointestinal tract. In the gut, it is secreted by the N cells in the ileum in response to fat ingestion. Its primary gastrointestinal functions are to inhibit gastric motility and gastric acid secretion (contributing to the 'ileal brake'), and to stimulate the release of histamine from mast cells and glucagon from the pancreas. It also causes vasodilation in the intestinal mucosa.

Explanation:
The gall bladder is a small sac under the liver that stores and concentrates bile produced by the liver, releasing it into the duodenum when needed for fat digestion. The liver makes bile, pancreas produces digestive enzymes, duodenum is the entry point.