Ans. a (Duodenum) (Ref. BDC, Vol. II, 3rd ed., 212)THE DUODENAL GLANDS OF BRUNNER (BRUNNER'S GLAND)# These lie in the SUBMUCOSA of the duodenum.# These are small, compound tubuloacinar glands.# They secrete mucus.RegionMajor characteristicsMucosal cell types at surfaceFunction of surface mucosal cellsEsophagus# Nonkeratinized stratified squamous epithelium# Skeletal muscle in muscularia externa (upper 1/3)# Smooth muscle (lower 1/3)--Stomach (body and fundus)Rugae: shallow pits; deep glandsMucous cellsSecrete mucus; form protective layer against acid; tight junctions between these cells probably contribute to the acid barrier of the epithelium Chief cellsSecrete pepsinogen and lipase precursor Parietal cellsEnteroendocrine (EE) cellsSecrete HCI and intrinsic factorSecrete a variety of peptide hormonesPylorusDeep pits; shallow branched glandsMucous cellsParietal cellsEE cellsSame as aboveSame as aboveHigh concentration of gastrinSmall intestineVilli, plicae, and cryptsColumnar absorptive cellsContain numerous microvilli that greatly increase the luminal surface area, facilitating absorptionDuodenumBrunner glands, which discharge alkaline secretionGoblet cellsSecrete acid glycoproteins that protect mucosal liningsPaneth cellsContain granules that contain lysozymeMay play a role in regulating intestinal floraEE cellsHigh concentration of cells that secrete cholecystokinin and secretinJejunumVilli, well developed plica, cryptsSame cell types as found in the duodenal epitheliumSame as aboveIleumAggregations of lymph nodes called Peyer patchesM cells found over lymphatic nodules and Peyer patchesEndocytose and transport antigen from the lumen to lymphoid cellsLarge intestineLacks villi, cryptsMainly mucus-secreting and absorptive cellsTransport Na+ (active) and water (passively) out of lumen