Anatomy and Physiology of the Pancreas, Animation

Summary

The pancreas is a vital gland in the abdomen that plays dual roles in both digestion and hormone regulation. It produces digestive enzymes and bicarbonate, which aid in the breakdown of proteins, fats, and carbohydrates. These enzymes are secreted in an inactive form to prevent self-digestion of pancreatic tissue. The pancreas also secretes hormones, including insulin and glucagon, to regulate blood sugar levels. Several hormones like cholecystokinin and secretin control enzyme secretion, while the islets of Langerhans produce other hormones like somatostatin and ghrelin that influence metabolic functions and food intake.

Takeaways

• 😀 The pancreas is a spongy gland located in the upper abdomen and serves both endocrine and exocrine functions.
• 😀 It stretches horizontally from the duodenum to the spleen and plays a key role in digestion and blood sugar regulation.
• 😀 The exocrine function produces digestive enzymes (proteases, lipase, and amylase) that help digest proteins, fats, and carbohydrates.
• 😀 Acini, clusters of exocrine cells, secrete digestive enzymes into ducts that converge to form the main pancreatic duct.
• 😀 The main pancreatic duct joins the bile duct before opening into the duodenum through the hepatopancreatic sphincter.
• 😀 An accessory pancreatic duct also connects to the duodenum, releasing pancreatic juice upstream of the hepatopancreatic sphincter.
• 😀 Pancreatic juice contains enzymes and sodium bicarbonate, which neutralizes stomach acid to protect the duodenum.
• 😀 Enzymes like proteases are secreted as inactive zymogens, which are only activated in the intestine to prevent damage to the pancreas.
• 😀 Trypsinogen, the inactive form of trypsin, is activated in the intestine by enterokinase, which then activates other enzymes.
• 😀 Several hormones control the secretion of pancreatic juice, including cholecystokinin (CCK) and secretin, which respond to food and stomach acid in the duodenum.
• 😀 The endocrine portion of the pancreas, consisting of the islets of Langerhans, produces hormones like insulin and glucagon to regulate blood glucose levels.

Q & A

What is the primary function of the pancreas?

The pancreas is both an exocrine and endocrine gland. It secretes digestive enzymes into ducts that lead to the intestine, and hormones into the bloodstream to regulate blood sugar levels, among other functions.

What are the main digestive enzymes produced by the pancreas?

The pancreas produces three main digestive enzymes: proteases (for protein digestion), lipase (for fat digestion), and amylase (for carbohydrate digestion).

How are the enzymes produced by the pancreas activated?

Most enzymes, especially proteases, are secreted as inactive pro-enzymes called zymogens. Once in the intestine, trypsinogen is activated into trypsin by the enzyme enterokinase, which then activates other zymogens.

What role does bicarbonate play in pancreatic juice?

Bicarbonate, produced by the pancreatic ducts, neutralizes stomach acid that arrives in the duodenum, providing a more favorable environment for the digestive enzymes to work.

What triggers the secretion of bile and pancreatic juice?

The secretion of bile and pancreatic juice is stimulated by the parasympathetic nervous system and certain hormones, including Cholecystokinin (CCK) and Secretin.

What is the role of Cholecystokinin (CCK) in digestion?

CCK stimulates the secretion of pancreatic enzymes in response to fatty acids and proteins in the duodenum. It also triggers the contraction of the gallbladder and relaxation of the hepatopancreatic sphincter to release bile and pancreatic juice.

How does Secretin affect the pancreas?

Secretin stimulates the secretion of bicarbonate by the pancreatic ducts in response to the arrival of stomach acid in the duodenum, helping to neutralize the acid.

What are the main functions of insulin and glucagon in blood sugar regulation?

Insulin lowers blood glucose levels by promoting glucose uptake and storage, while glucagon raises blood glucose levels by stimulating glucose production and inhibiting its breakdown in the liver.

What is the function of amylin produced by beta-cells of the pancreas?

Amylin, co-secreted with insulin, inhibits food intake, delays gastric emptying, and suppresses glucagon secretion, helping to regulate blood glucose levels.

What is the role of somatostatin in the endocrine system?

Somatostatin inhibits the secretion of various hormones, including growth hormone, thyroid-stimulating hormone, and gastrointestinal hormones, acting as a broad inhibitor of hormone release.