This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: G.I.T, Subject name: Physiology
All of the following increase small intestinal motility except 
Select and explain. 
A. Secretin, B. Gastroenteric reflex, C. CCK, D. Serotonin
A: Secretin
Answer: A: Secretin 
Explanation: Secretin inhibits small intestinal motility. Factors that increase the peristaltic activity of small intestine Hormonal- Gastrin, CCK, insulin, motilin and serotonin Neural - Duodenal distension by chyme, gastroenteric reflex, gastroileal reflexes, parasympathetic (ACh) stimulation. Factors that decrease the peristaltic activity of small intestin: Hormone- Secretin and glucagon Neural- Sympathetic stimulation Gastroileal reflex- On reaching the ileocecal valve, the chyme is sometimes blocked for several hours until the person eats another meal. At that time, a gastroileal reflex intensifies peristalsis in the ileum and forces the remaining chyme through the ileocecal valve into the cecum of the large intestine. Ref: Guyton and Hall 13th edition Pgno: 813