Identify the location and function of the following:
$(1)$ Goblet cells
$(2)$ Islets of Langerhans

(N/A) $(1)$ Goblet cells are found in the mucosal epithelium of the digestive tract and are responsible for the secretion of mucus,which helps in lubrication and protection of the gut lining.
$(2)$ Islets of Langerhans are found in the pancreas and are responsible for the secretion of hormones,specifically insulin and glucagon,which regulate blood glucose levels.