Duodenum, the first region of small intestine has characteristic rounded Brunner's glands. Brunner's glands secrete large amount of mucus and bicarbonates to protect the duodenal mucosa and to neutralise the acidic chyme arriving from the pylorus. They also secrete 2 hormones - secretin and cholecystokinin under the influence of acid chyme. These two hormones circulate in the blood and stimulate the target organs.