Pancreas. Illustration of the secretory cells of the human pancreas, showing an islet of Langerhans (centre) surrounded by pancreatic acini. The pancreatic acini produce digestive enzymes (white spots) that pass through ducts (yellow) into the small intestine. The cells of the islet are involved in the endocrine function of hormone production. The hormones (blue & white spots) are secreted directly into the bloodstream. These hormones include insulin (blue spots, produced by beta cells) which lowers blood sugar levels, and glucagon (white spots, produced by alpha cells) which raises blood sugar.