Pancreatic secretion

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Pancreatic secretion


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USMLE® Step 1 questions

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Pancreatic secretion

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USMLE® Step 1 style questions USMLE

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A group of researchers is studying the functions and features of the pancreatic exocrine secretions. They take samples of pancreatic secretions at various stages in test subjects, including 30 minutes after eating a meal, and in subjects who have fasted. Which of the following is true regarding the pancreatic exocrine secretions?


The pancreas is a long, skinny gland the length of a dollar bill and is located in the upper abdomen, or the epigastric region, behind the stomach. It has endocrine functions meaning it secretes hormones into the blood that eventually act upon other target tissues.

For example, alpha and beta cells in the pancreas make hormones like insulin and glucagon that are secreted into the bloodstream to regulate blood sugar levels.

However, approximately 90% of the pancreas is dedicated to its exocrine functions.

The exocrine pancreas secretes enzymes and fluids that help neutralize and digest food within the intestines.

The exocrine pancreas can be divided into lobules, each of which contain lots of functional units called an acinus.

An acinus is a cluster of acinar cells that all work together to make digestive enzymes.

In fact, the word “acinus” means “berry” which describes the berry-like appearance of these cell clusters.

Each acinus secretes digestive enzymes which flow into small intercalated ducts that are lined by ductal cells.

These ductal cells secrete bicarbonate and fluids that make up the liquid portion of pancreatic fluid, and ultimately help to neutralize the acidic stomach contents as they enter the intestines.

The intercalated ducts merge together forming an intralobular duct which join with other interlobular duct, and finally drain into the main pancreatic duct.

The main pancreatic duct travels through the length of the pancreas and drains into the duodenum.

Now let’s look at the enzymes made by the acinar cells. The main enzymes include pancreatic amylase which breaks down carbohydrates; trypsin and chymotrypsin, which break down proteins; and lipase which break down lipids.

Now as it turns out, macromolecules like carbohydrates, proteins, and lipids are also found in the cells of the pancreas.

Thus, in order protect the pancreas from destroying itself, the acinar cells manufacture inactive forms of the enzymes called proenzymes, or zymogens.


Pancreatic secretion refers to the production and release of enzymes and hormones by the pancreas, a gland located behind the stomach. These enzymes and hormones aid in the digestion of food and the regulation of blood sugar levels. The pancreas produces both exocrine and endocrine secretions. Exocrine secretions include enzymes such as amylase, lipase, and trypsin, which are released into the small intestine to aid in the digestion of carbohydrates, fats, and proteins. Endocrine secretions include insulin and glucagon, which regulate blood sugar levels.


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  4. "Principles of Anatomy and Physiology" Wiley (2014)
  5. "Tissue-based map of the human proteome" Science (2015)
  6. "Milestones in the history of diabetes mellitus: The main contributors" World Journal of Diabetes (2016)

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