Which factors decrease gastric emptying rate (increase time in the stomach)?

• A. Liquids and gastric distention
• B. Solids, acids, and fats, and sympathetic-acting drugs like anticholinergics and opioids
• C. Cholinergic stimulation
• D. Guanethidine and cholinergic drugs

Answer: (B)

Gastric emptying slows when the meal requires more processing and when duodenal feedback dampens stomach contractions. Solids take longer to grind into a passable form, so their presence slows the rate of emptying compared with liquids. Fat in the meal activates gut hormones like cholecystokinin, which slows gastric motility to give fat more time to be emulsified and digested. Acids in the chyme entering the duodenum also trigger enterogastric reflexes and hormonal signals that reduce stomach emptying to protect the intestine from sudden, overly acidic contents. In addition, sympathetic-acting influences decrease smooth muscle activity in the stomach; drugs with anticholinergic or opioid actions suppress motility and therefore lengthen the time the contents stay in the stomach. By contrast, activating cholinergic (parasympathetic) pathways speeds up contractions and increases the rate of emptying, and blocking sympathetic signaling (as with guanethidine) would tend to remove inhibitory input rather than slow emptying.