pancreas , liver , and gallbladder

Bile Storage and Function

• Bile Storage: Bile is stored in the gallbladder and concentrated there.

• Hormonal Trigger: The presence of food in the digestive system triggers hormone release, causing the gallbladder to squeeze bile.

• Transport: Bile travels through the cystic duct, into the common bile duct, and into the duodenum.

• Role in Digestion: Bile assists in emulsifying fats, allowing enzymes to begin fat breakdown.

Pancreatic Function

• Endocrine Role: The pancreas regulates blood sugar by secreting insulin.

• Exocrine Role: Functions as a critical exocrine gland in digestion, producing enzymes and sodium bicarbonate.

• Enzyme Production: Pancreatic enzymes act on macromolecules: carbohydrates, proteins, lipids, and nucleic acids.

• Sodium Bicarbonate Function: Neutralizes acidic gastric juice in the duodenum, activating pancreatic enzymes and allowing them to function in a less acidic environment.

Anatomy of the Pancreas

• Location: Retroperitoneal organ, about six inches long.

• Parts of the Pancreas: Composed of the head (thicker part), body, and tail.

• Pancreatic Duct: Main duct through which pancreatic juice is excreted into the duodenum.

  • Accessory Duct: A secondary opening that branches off the main pancreatic duct.

  • Hepatopancreatic Ampulla: Where the common bile duct and pancreatic duct join before entering the duodenum.

  • Sphincter of Oddi: Controls the opening/closing of the ampulla, regulating bile and pancreatic juice flow into the duodenum.

Digestive Enzymes and Their Activation

• Enzyme Categories: Enzymes produced include proteases, amylases, and lipases.

• Proteolytic Enzymes: Proteins are broken down by trypsin and chymotrypsin.

  • Trypsin Activation: Released as trypsinogen (inactive) and converted to trypsin in the duodenum using entero kinase.

• Lipase Function: Breaks down lipids, impactful for fat digestion.

Conditions Affecting the Pancreas

• Cystic Fibrosis: Affects ducts in the pancreas, hindering enzyme secretion, leading to digestive difficulties.

• Inflammation: Conditions like chronic pancreatitis increase the risk of pancreatic cancer and can cause gastrointestinal pain or dysfunction.

• Cancer Statistics: Pancreatic cancer is the fourth leading cause of cancer deaths in the U.S., often detected late and more prevalent in males.

Structure and Function of the Liver

• Liver Size and Location: Second largest organ, located in the right upper quadrant of the abdomen, weighing about three pounds.

• Liver Lobes: Composed of a right lobe (larger) and a left lobe, connected to abdominal structures via ligaments like the falciform ligament and ligamentum teres.

Functions of the Liver

• Bile Production: Hepatocytes produce bile, which helps emulsify fats in the digestive process.

• Metabolism: Maintains blood glucose levels, stores and synthesizes glycogen, and manages triglycerides and cholesterol.

• Nitrogenous Waste Management: Converts ammonia (a byproduct of protein breakdown) into urea for safe excretion.

• Vitamins and Mineral Storage: Stores vitamins and minerals, including iron, which can accumulate in genetic disorders.

• Detoxification: Processes drugs and alcohol.

• Activation of Vitamin D: Converts precursors into active vitamin D, playing a role in calcium metabolism.

Bilirubin Processing and Jaundice

• Bilirubin: Byproduct of red blood cell breakdown processed by the liver.

  • Jaundice: Yellowing of the skin and eyes due to bilirubin buildup; often seen in newborns.

• Treatment for Jaundice: Using blue light therapy helps convert bilirubin to a more manageable form for excretion.

Gallbladder Function and Gallstones

• Function: Primarily a storage site for bile, releasing it as needed into the digestive tract.

• Gallstone Development: Caused by excess cholesterol and can result in cystic duct blockages, leading to pain and inflammation.

• Risk Factors for Gallstones: Female gender, high fat diet, being over 40, and overweight.

• Treatment Options: Surgery or lithotripsy (using sound waves). Lifestyle adjustments can also help manage gallstone risks.