What Does The Pancreas Actually Do??

The Pancreas: A Comprehensive Guide to Anatomy, Function, and Clinical Significance

“Do you know what the pancreas does?”

*Blank stare*

If I had a penny for every blank stare I received after asking that question I would probably have £2.79.

Hidden behind your stomach lies an organ that rarely gets the recognition it deserves.

The pancreas!

Weighing no more than a small apple (80-90 grams), it orchestrates two of life's most essential processes: digestion and blood sugar control.

When it works well, you never notice it.

When it falters, the consequences ripple through every system in your body.

Finding the Pancreas

Picture a tadpole resting horizontally across your upper abdomen. That's your pancreas. It stretches 12-15 centimetres from right to left, tucked behind the stomach at the level of your first and second lumbar vertebrae. The head, the widest part at 6 centimetres, nestles into the curve of your duodenum. The body spans 4 centimetres. The tail, just 2 centimetres wide, reaches toward your spleen.

This placement is precise for a reason. The pancreas sits at the crossroads of digestion, perfectly placed to deliver its precious cargo of enzymes and hormones exactly where they're needed, exactly when they're needed.

The pancreas sits snug into the duodenum (the first part of the small bowel; nearest to the stomach)

The Architecture of Dual Purpose

The pancreas is essentially two organs in one. Most of it (about 99%) consists of tiny factories called acinar cells that produce digestive enzymes. Coinciding with this, there are tiny hormone-producing cells. These are the islets of Langerhans, named after the medical student who discovered them in 1869.

The human pancreas contains approximately one million islets, each measuring just 0.2 millimetres across. Despite occupying only 1-2% of pancreatic real estate, these islets receive 10-15% of the organ's blood flow. This rich blood supply (mainly from the superior mesenteric artery, splenic artery and gastro-duodenal artery) reflects their critical mission: maintaining the delicate balance of blood sugar that keeps you alive.

The Ductal System: Pancreas Plumbing

A sophisticated network of ducts collects enzyme-rich juice from across the pancreas. The main pancreatic duct, measuring 2-3 millimetres in diameter and spanning 15-20 centimetres, runs the organ's length before joining the common bile duct. Together, they empty into the duodenum through a muscular valve called the sphincter of Ampulla.

But these ducts do more than transport. They actively secrete bicarbonate (stimulated by the hormone secretin), creating an alkaline environment that neutralises stomach acid. This maintains duodenal pH between 8.0-8.5; the sweet spot for enzyme activity. Without this buffering system, your digestive enzymes would fail. The pancreas produces up to 2 litres of bicarbonate-rich fluid daily, matching the stomach's acid output accurately.

Bile and pancreatic juice escape through the ampulla into the small bowel to digest food

The Digestive Symphony

Every time you eat, your pancreas starts to work. It produces between 1.5 and 4 litres of pancreatic juice daily; a cocktail of water, bicarbonate, and over twenty different digestive enzymes.

Though enzymes constitute just 0.5% of this juice by volume, they pack the digestive punch.

Three types of enzymes do the heavy lifting:

• Amylase breaks down carbohydrates (normal serum levels: 23-85 U/L)

  • If amylase is greater than 250U/L this could indicate inflammation of the pancreas (known as acute pancreatitis)

• Lipase digests fats (normal serum levels: 0-160 U/L)

• Proteases dismantle proteins

These enzymes are so powerful they could digest the pancreas itself. The solution? They're manufactured as inactive precursors; molecular sleeper agents that only activate once they reach the small intestine. The median time from enzyme synthesis to secretion? Just 86 minutes. Clever design prevents self-destruction.

The process unfolds in three acts. First, the mere sight, smell, or thought of food triggers the cephalic phase, contributing 20-25% of enzyme output through vagal nerve stimulation. Your stomach stretching during a meal adds another 5-10%. But the main event, 50-80% of enzyme secretion, happens when food enters your duodenum.

A meal needs to exceed 500 kilocalories to trigger maximal pancreatic stimulation. High-fat meals can increase enzyme output 2-4 fold compared to high-carbohydrate meals. Your pancreas reads your plate and responds accordingly.

The Hormone Factory

Within those tiny islets, four cell types work in concert:

• Beta cells (65-80%) produce insulin

• Alpha cells (15-20%) make glucagon

• Delta cells (3-10%) secrete somatostatin

• PP cells (3-5%) release pancreatic polypeptide

Insulin gets most of the attention, and for good reason. This hormone unlocks your cells, allowing glucose to enter and fuel your body. Without it, sugar accumulates in your blood while your cells starve; the essence of diabetes.

The insulin response follows a characteristic two-phase pattern. The first phase; a rapid spike lasting 10 minutes, releases pre-formed insulin.

The second phase involves newly synthesised insulin, sustaining the response as long as glucose remains elevated. Peak trypsin output after meals reaches 90% of maximal stimulation, demonstrating how finely tuned this system is.

But insulin doesn't work alone. Glucagon acts as its counterbalance, raising blood sugar when it drops too low. Somatostatin serves as the brake pedal, with plasma levels rising from 11 to 18 pmol/L after meals, enough to modulate both enzyme and hormone secretion. Together, they maintain blood glucose within the narrow range compatible with life.

Image Credit: DiBtv/Shutterstock.com

When Things Go Wrong

Pancreatic insufficiency develops when enzyme production drops below 10% of normal, meaning you've lost 90% of your pancreatic function before symptoms appear. This reserve capacity explains why pancreatic disease often goes undetected until advanced stages.

The symptoms of malabsorption are:

• Chronic diarrhoea

• Steatorrhea (fatty stools)

• Weight loss despite normal appetite

• Abdominal bloating and pain

Steatorrhea….those pale, bulky, foul-smelling stools that float, signals severe fat malabsorption. The medical team is called pancreatic exocrine insufficiency.

When lipase activity falls below 10% of normal, up to 40% of dietary fat passes undigested. This means losing not just calories but fat-soluble vitamins (A, D, E, K), leading to night blindness, osteoporosis, bleeding disorders, and neurological problems.

Diagnosis relies on several tests. Faecal elastase-1 levels below 200 μg/g suggest insufficiency. Just make sure you send a solid sample. A liquid sample can dilute the elastase leading to a false positive result (you are tested positive for pancreatic exocrine insufficiency, when in fact you don’t have the condition; you just sent a watery/diluted stool sample.

The treatment seems straightforward: enzyme replacement therapy. Modern preparations deliver 25,000-40,000 units of lipase per meal. But timing matters. Too early, and stomach acid destroys the enzymes. Too late, and they miss the food. Special enteric coatings dissolve only at pH above 5.5, pharmaceutical precision meeting physiological need. I will likely deep dive this in another newsletter.

Pancreatic Lipase….in a capsule

The Adaptive Organ

Your pancreas reads your diet like a book. Chronic high-fat diets can increase lipase output up to 4-fold within 2-3 weeks. Switch to carbohydrates, and amylase production rises proportionally. This adaptation optimises your digestive capacity to match your eating patterns.

The pancreas even responds to meal anticipation. Those mouth-watering moments before eating? Your pancreas is already preparing, contributing that 20-25% of enzyme output before food even touches your lips. This cephalic phase response can be conditioned…Pavlov's dogs had primed pancreases too.

Any interesting research?

Pancreatic polypeptide levels rise 5-10 fold after meals, remaining elevated for 4-6 hours. Beyond local effects, it influences appetite centre in the hypothalamus and may reduce food intake by 25% in experimental settings. These discoveries suggest the pancreas plays a broader role in metabolism than previously thought.

A summary with numbers

Understanding pancreatic function through numbers reveals its sophistication:

• Daily enzyme production: 6-10 grams of pure protein

• Bicarbonate concentration: 140 mEq/L (5 times higher than blood)

• Blood flow to islets: 10-15% of total, despite being 1-2% of mass

• Enzyme reserve: 90% can be lost before symptoms appear

• Meal threshold for maximal stimulation: 500 kilocalories

• Time from enzyme synthesis to secretion: 80-90 minutes

Putting it all together

The pancreas exemplifies biological elegance: two distinct functions housed in one organ, multiple fail-safes preventing self-destruction, and remarkable adaptability to changing demands. It coordinates with the brain, responds to hormones from the gut, and adjusts its output based on what you eat.

This hidden powerhouse deserves more respect.

Every meal you enjoy, every stable blood sugar reading….you can thank your pancreas! It works tirelessly, producing enough enzymes annually to digest several times your body weight in food. It secretes enough bicarbonate to neutralise gallons of stomach acid. It maintains blood glucose within a range so narrow that deviation by just a few points triggers alarm bells throughout your body.

Understanding your pancreas is recognising the sophisticated machinery that keeps you nourished and energised. In health, it operates silently. In disease, its absence is profoundly felt. Perhaps that's the ultimate testament to its importance; we only truly appreciate the pancreas when we lose it.

The next time you sit down to a meal, spare a thought for this remarkable organ. In the time it takes you to eat, it will have sensed, calculated, and delivered precisely calibrated doses of enzymes and hormones. No conscious effort required. That's the genius of the pancreas…complexity serving simplicity, silence masking sophistication.

Struggling with digestive issues that affect your daily life? Invest in your gut health with a private, personalised consultation where I will explore your specific symptoms and develop a targeted treatment plan. Take the first step toward digestive wellness today: https://bucksgastroenterology.co.uk/contact/

References

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3. https://www.kenhub.com/en/library/anatomy/the-pancreas

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6. O'Keefe SJ et al. Pancreatic enzyme synthesis and turnover in human subjects. Am J Physiol. 1994 May;266(5 Pt 1):G816-21.

7. Treacy J et al. Evaluation of amylase and lipase in the diagnosis of acute pancreatitis. ANZ J Surg. 2001 Oct;71(10):577-82.

8. Joachim Mössner; New Advances in Cell Physiology and Pathophysiology of the Exocrine Pancreas. Dig Dis 1 April 2011; 28 (6): 722–728

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10. Campbell, J.E., Newgard, C.B. Mechanisms controlling pancreatic islet cell function in insulin secretion. Nat Rev Mol Cell Biol 22, 142–158 (2021).

11. Zou CY, Gong Y, Liang J. Metabolic signaling of insulin secretion by pancreatic β-cell and its derangement in type 2 diabetes. Eur Rev Med Pharmacol Sci. 2014;18(15):2215-27.

General Disclaimer

Please note that the opinions expressed here are those of Dr Hussenbux and do not necessarily reflect the positions of Buckinghamhsire Healthcare NHS Trust. The advice is intended as general and should not be interpreted as personal clinical advice. If you have problems, please tell your healthcare professional, who will be able to help you.