Histological Structure of Liver, Pancreas, Gall Bladder

Flashcards about the histological structure of the liver, pancreas, and gall bladder.

What organs are associated with the digestive tract?

Major salivary glands, pancreas, liver, gallbladder.

What are the functions of the organs associated with the digestive tract?

Facilitate movement & digestion within the gastrointestinal tract and secrete digestive enzymes, bile, and immune components

What are the main functions of Salivary Glands?

Moisten and lubricate food & oral mucosa, initiate carbohydrate and lipid digestion, and secrete innate immune factors.

What are the functions of the liver?

Exocrine secretion is bile for fat digestion, metabolism of carbohydrates & proteins, detoxification of substances & drugs, synthesizes plasma proteins and coagulation factors

What is the fucntion of the gallbladder?

Stores and concentrates bile and releases bile into the duodenum.

What is the pancreas?

Mixed exocrine–endocrine gland

Describe the structure of the Pancreas.

Retroperitoneal, elongated organ divided into head, body, and tail.

What are the functions of the exocrine and endocrine portions of the Pancreas?

Serous acini produce digestive enzymes. Islets of Langerhans produce hormones.

Describe Pancreatic Cancer

Usually carcinoma of duct cells, most frequent in pancreatic head, often asymptomatic until advanced, early detection is difficult with a poor prognosis, facilitated by sparse connective tissue around ducts.

Describe the Exocrine Pancreas - Histology

Protein-secreting pyramidal cells, central lumen, no myoepithelial cells, drained by intercalated ducts lined by centroacinar cells

How much alkaline pancreatic juice does the pancreas secrete?

1.5 L/day of alkaline pancreatic juice

Why is alkaline pancreatic juice important?

HCO₃ ⁻ neutralizes gastric acid in duodenum

What enzymes are within the pancreatic juice?

Proteases (as zymogens: trypsinogen, chymotrypsinogen, etc.), α-Amylase, Lipases, Nucleases (DNAase, RNAase)

What are the Enzyme Activation & Protection Mechanisms that regulate the exocrine pancreas?

Protease activation restricted to duodenum, trypsin inhibitor in zymogen granules, and high pH in ducts (HCO₃ ⁻) keeps enzymes inactive

What are the causes of acute pancreatitis?

Proenzymes activated within the pancreas causing autodigestion due to infection, gallstones, alcohol, drugs, or trauma

What are the features of chronic pancreatitis?

Progressive fibrosis and loss of pancreatic function

How are Enteroendocrine Hormones involved in Regulation of Exocrine Secretion?

Cholecystokinin (CCK) stimulates acinar enzyme secretion and Secretin stimulates HCO₃ ⁻ and water secretion from ducts.

How is the Nervous System involved in Regulation of Exocrine Secretion?

Parasympathetic (autonomic) nerve fibers stimulate both acinar & ductal cells.

Describe the liver

Largest internal organ (~1.5 kg, ~2% body weight)

What is the dual blood supply of the liver?

75% via nutrient-rich portal vein and 25% via oxygen-rich hepatic artery

How is bile produced and transported?

Bile produced by hepatocytes → bile canaliculi → bile ducts → gallbladder or duodenum

What are the Hepatocyte Functions?

Exocrine: bile production, Endocrine: plasma proteins (albumin, fibrinogen, transferrin), Gluconeogenesis, Detoxification of drugs & toxins, Amino acid deamination → urea, Storage: glycogen, triglycerides, vitamins, iron, Phagocytosis: aged RBCs by Kupffer cells

Describe the Classic Hepatic Lobule

Hexagonal unit with central vein

What are the structures within the Portal triads at periphery of the hepatic lobule?

Portal vein branch, Hepatic artery branch, Bile ductule

How does blood flow through the Hepatic Lobule?

Blood flows from portal triads → sinusoids → central vein

What are Bile Canaliculi?

Tiny channels between hepatocytes for bile flow

Describe the Bile Canaliculi network

Form bile canaliculi network → canals of Hering → bile ductules

How does bile flow?

Center → periphery (opposite to blood flow)

What occurs in Hepatic Acinus Zone I (periportal)?

Highest O₂, active protein synthesis

What occurs in Hepatic Acinus Zone III (centrilobular)?

Lowest O₂, lipid metabolism, drug detoxification, ischemic injury site

Outline the features of Cirrhosis

Chronic liver injury → fibrosis & stellate cell activation

Outline the features of Fatty Liver Disease (Steatosis)

Triglyceride accumulation in hepatocytes

What causes Neonatal Jaundice?

Due to immature hepatocyte SER & low bilirubin conjugation

How does Liver Regeneration occur?

Strong regenerative capacity via hepatocyte mitosis and compensatory hyperplasia after injury/ resection. Role of liver stem (oval) cells in severe injury

How is bile transported to the gallbladder and duodenum?

Bile from hepatocytes → bile canaliculi → ducts → gallbladder/duodenum

What is the function of the Gallbladder?

Stores and concentrates bile

How is bile released released?

CCK stimulates bile release after fatty meals

What causes Gallstones (Cho

Excess cholesterol or bilirubin in bile → stone formation