Module 2 The Endocrine System

Lessonn 1.2.5

1.2.5 page 2

Explore

The Anatomy of the Pancreas

Located in the space between the stomach and the first loop of the small intestine, the pancreas is a dual function organ. In Biology 20, you learned about the digestive enzymes that it produces. Scattered among the enzyme-producing cells are clusters of cells called the islets of Langerhans (or simply islets) which produce pancreatic hormones. The vast majority of cells in the islets are beta cells, which produce insulin. A few elongated alpha cells produce glucagon. Look at the photomicrograph above and see if you can distinguish the two types of cells in the islet.

pancreas: a gland with dual function; the non-endocrine part secretes digestive enzymes into the intestine through the pancreatic duct, while the endocrine portion called the islets of Langerhans secretes insulin and glucagon into the bloodstream

islets: also called the islets of Langerhans; composed of clusters of alpha and beta cells which secrete glucagon and insulin, respectively, into the blood

alpha cells: cells in the islets that secrete glucagon

beta cells: cells in the islets that secrete insulin

insulin: a hormone, secreted by the beta cells in the islets of the pancreas, which lowers blood glucose levels by promoting the uptake of glucose by most cells of the body, and the synthesis and storage of glycogen in the liver; also stimulates protein and fat synthesis

glucagon: a hormone, secreted by the alpha cells in the islets of the pancreas, which raises blood glucose levels by stimulating liver cells to convert glycogen to glucose; also stimulates fat cells (adipose cells) to convert fat to glucose

Read

Watch and Listen

Study Figure 13.24 on page 456 of your textbook to help you do this. HOWEVER, IN THIS FIGURE THE LABELS FOR THE ALPHA AND BETA CELLS SHOULD BE REVERSED. THE BETA CELLS ARE MORE NUMEROUS.

To give you a better understanding of the structures of the pancreas, read page 456 in your textbook OR view the video below.

The Pancreas

Try This

TR 1.

To apply your knowledge of the anatomy of the pancreas and the function of its various structures, label the structures on the Pancreatic Tissue and Associated Structures Handout and on the diagram, annotate the structures with their functions. Several structures are shown that you have studied in previous lessons. After you have completed the exercise, check your answers and file your work in your course folder.

Inquiry into Biology (Whitby, ON: McGraw-Hill Ryerson, 2007), BLM 13.4.1. Reproduced by permission.

Check your work.

Self-Check Answers

Inquiry into Biology (Whitby, ON: McGraw-Hill Ryerson, 2007), BLM 13.4.1. Reproduced by permission.