Digestive System Accessory Organs

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Questions and Answers

What is the primary function of bile salts?

  • Emulsification of ingested fat (correct)
  • Production of fibrinogen and thrombin
  • Secretion of immunoglobulins
  • Degradation of hemoglobin in senescent erythrocytes

Which of the following is a consequence of impaired bilirubin uptake and conjugation by the liver?

  • Increased levels of IgA in the blood
  • Jaundice (correct)
  • Steatorrhea (fatty feces)
  • Decreased production of fibrinogen

Where are plasma proteins, such as fibrinogen and thrombin, synthesized?

  • Rough endoplasmic reticulum of liver cells (correct)
  • Intestinal epithelium
  • Kupffer cells of the spleen
  • Lamina propria of the gut

What is the role of IgA in the immune system?

<p>Defense against pathogens in the gut (A)</p> Signup and view all the answers

How does bile duct occlusion impact IgA levels in the blood?

<p>Causes a decrease in IgA levels to nearly one-tenth of normal (A)</p> Signup and view all the answers

What is the primary function of Kupffer cells?

<p>Phagocytosis of senescent erythrocytes (C)</p> Signup and view all the answers

Which of the following is NOT a characteristic of bilirubin?

<p>Synthesized by plasma cells in the lamina propria (C)</p> Signup and view all the answers

Which of the following is NOT a consequence of a lack of bile secretion?

<p>Increased levels of fibrinogen in the blood (B)</p> Signup and view all the answers

What is the role of the rough endoplasmic reticulum (rER) in the synthesis of plasma proteins?

<p>Packaging and secretion of proteins (D)</p> Signup and view all the answers

Which of the following arteries does not supply blood to the pancreas?

<p>Inferior mesenteric artery (D)</p> Signup and view all the answers

What is the primary function of the fenestrated capillaries in the islets of Langerhans?

<p>To facilitate the rapid exchange of hormones between the blood and the endocrine cells (A)</p> Signup and view all the answers

Which of the following enzymes is responsible for hydrolyzing triglycerides into fatty acids and monoglycerides?

<p>Lipase (C)</p> Signup and view all the answers

Which of these components are part of the biliary tree?

<p>All of the above (D)</p> Signup and view all the answers

Which of the following nerve supplies the pancreas?

<p>Vagus nerve (B)</p> Signup and view all the answers

Which of the following is NOT a function of the gallbladder?

<p>Produce Bile (D)</p> Signup and view all the answers

What is the primary reason for the inactive form of pancreatic enzymes being produced?

<p>To prevent autodigestion of the pancreas (B)</p> Signup and view all the answers

What is the Glisson's capsule made of?

<p>Connective tissue (D)</p> Signup and view all the answers

Why are the blood vessels of the Glisson's capsule located on its underside?

<p>To ensure efficient filtering of the blood (A)</p> Signup and view all the answers

What does the term "proenzyme" refer to in the context of pancreatic enzymes?

<p>An enzyme that is inactive until it is cleaved by another enzyme (C)</p> Signup and view all the answers

Which of the following is not a type of cell found in the islets of Langerhans?

<p>Gamma cells (D)</p> Signup and view all the answers

What is the common bile duct formed by?

<p>Hepatic duct and cystic duct (A)</p> Signup and view all the answers

What is the primary function of the pancreatic-duodenal branches of the hepatic arteries?

<p>To supply blood to the pancreas (D)</p> Signup and view all the answers

What does the presence of an easily palpable liver edge indicate?

<p>Possible liver enlargement (C)</p> Signup and view all the answers

Which of the following correctly describes the capillary network in the exocrine pancreas?

<p>Continuous capillaries (B)</p> Signup and view all the answers

What is the primary function of the Sphincter of Oddi?

<p>To regulate the flow of bile into the small intestine (B)</p> Signup and view all the answers

Which of the following is not a pancreatic enzyme that helps in the digestion of proteins?

<p>Lipase (C)</p> Signup and view all the answers

What is the primary function of centro-acinar cells?

<p>Connect the acinus to the intercalated ducts (B)</p> Signup and view all the answers

What distinguishes the lining epithelium of the duct system from the lining epithelium of the acini?

<p>The duct system lining epithelium is involved in water and bicarbonate transport, while the acini lining epithelium secretes digestive enzymes. (C)</p> Signup and view all the answers

How does the arrangement of the intercalated ducts differ from the intralobular ducts?

<p>Intercalated ducts converge to form intralobular ducts, while intralobular ducts merge to form interlobular ducts. (B)</p> Signup and view all the answers

What is the primary function of the Interlobular Ducts?

<p>Transport of water and bicarbonate ions (D)</p> Signup and view all the answers

What is the relationship between the Vagus nerve and pancreatic secretion?

<p>Vagus nerve stimulation contributes to exocytosis and secretion accumulation. (B)</p> Signup and view all the answers

What is the significance of bicarbonate ions in the pancreatic secretion?

<p>They neutralize the acidic chyme from the stomach. (C)</p> Signup and view all the answers

Which of the following structures is NOT directly involved in the production of pancreatic juice?

<p>Intralobular ducts (B)</p> Signup and view all the answers

What is the primary role of the lining epithelium of the intercalated ducts?

<p>To transport water and bicarbonates ions into the lumen. (A)</p> Signup and view all the answers

What distinguishes the Interlobular Ducts from the Intralobular Ducts?

<p>Interlobular ducts are found in the connective tissue septa between lobules, while intralobular ducts are within lobules. (C)</p> Signup and view all the answers

How does the pancreas's location contribute to its function?

<p>Its location near the duodenum allows for easy delivery of pancreatic juice to the small intestine. (D)</p> Signup and view all the answers

Which of the following is NOT a characteristic of the process of insulin secretion?

<p>Insulin secretion is stimulated by low blood glucose levels. (B)</p> Signup and view all the answers

What is the role of glucokinase in the liver in response to insulin?

<p>Glucokinase increases the uptake of glucose from the bloodstream into liver cells. (D)</p> Signup and view all the answers

Which of the following describes the fate of insulin-containing vesicles after their release?

<p>They fuse with primary lysosomes and are degraded by lysosomal enzymes. (B)</p> Signup and view all the answers

What is the primary function of somatostatin in regulating blood glucose levels?

<p>Somatostatin decreases insulin and glucagon secretion. (A)</p> Signup and view all the answers

What is the primary role of glucagon in maintaining blood glucose levels?

<p>Glucagon increases the breakdown of glycogen and gluconeogenesis in the liver. (C)</p> Signup and view all the answers

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Flashcards

Muscularis Externa

A layer of muscle in the gastrointestinal tract responsible for peristalsis.

Hepatocytes

Liver cells that perform metabolic, secretory, and endocrine functions.

Cystic Duct

Duct that connects the gallbladder to the common bile duct.

Sphincter of Oddi

Muscle valve controlling bile and pancreatic juice flow into the duodenum.

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Glisson's Capsule

Thin connective tissue surrounding the liver, contains blood vessels.

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Liver Regeneration

The liver's ability to regrow and restore its tissue after injury or partial removal.

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Biliary Tree

Network of ducts that transport bile from the liver to the gallbladder and duodenum.

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Exocytosis

A process where secretory granules discharge their contents outside the cell.

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Glucagon

A hormone secreted by alpha-cells that raises blood glucose levels during hypoglycemia.

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Somatostatin

A hormone that inhibits the secretion of insulin and glucagon, slowing nutrient uptake.

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Granulolysis

The breakdown of secretory granules by lysosomal enzymes.

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Glycogen

Stored form of glucose in the liver and muscle for later energy use.

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Plasma Proteins Synthesis

Plasma proteins like fibrinogen and thrombin are synthesized in the liver.

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Emulsifying Action of Bile Salts

Bile salts help absorb dietary fats by emulsifying them.

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Steatorrhea

A condition characterized by unusually fatty feces due to fat malabsorption.

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Bilirubin

A toxic greenish pigment resulting from the breakdown of hemoglobin from old red blood cells.

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Kupffer Cells

Liver cells that remove bilirubin and other toxins from the blood.

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Jaundice

Abnormal accumulation of bilirubin in the blood, leading to yellowing of the skin and eyes.

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Secretory IgA

An antibody synthesized in the gut to protect mucosal surfaces, complexed with a secretory component.

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Conjugation of Bilirubin

Process where bilirubin is converted to a water-soluble form in the liver for excretion.

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Endocytosis of Hormones

Liver cells take up hormones via receptor-mediated endocytosis to regulate bodily functions.

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Translation

The process where mRNA is converted into an amino acid sequence by tRNA.

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Trypsinogen

An inactive precursor that hydrolyzes proteins into smaller peptides or amino acids.

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Chymotrypsinogen

An inactive enzyme that, once activated, breaks down proteins into smaller peptides or amino acids.

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Procarboxypeptidase

A precursor enzyme that hydrolyzes small proteins into peptides or amino acids when activated.

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Lymph Capillaries

Lymphatic vessels that drain fluid and immune cells from tissues to lymph nodes.

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Vagus Nerves

A cranial nerve that supplies autonomic control to various organs, including the pancreas.

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Pancreatic-duodenal Branches

Branches of the hepatic arteries supplying blood to the duodenum and pancreas.

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Enzymes Activation

The process where enzymes are produced in inactive forms and activated in the intestine to prevent autodigestion.

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Amylase

An enzyme that breaks down starch and glycogen into glucose and small saccharides.

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Islet of Langerhans

Clusters of endocrine cells in the pancreas that secrete hormones such as insulin and glucagon.

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Exocrine pancreas

A secretion-producing organ located posterior to the stomach that secretes digestive enzymes.

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Centro-acinar cells

Cells that are pale-staining with low density, continuous with intercalated ducts, and involved in secretion.

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Intercalated ducts

Slender tubes that drain acini and converge into larger ducts.

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Intralobular ducts

Ducts lined by low columnar epithelium with goblet cells, active in transporting water and bicarbonate.

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Interlobular ducts

Ducts found between lobules, with the same epithelium as intralobular ducts, contributing to secretion volume.

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Bicarbonate ions

Ions that neutralize acidic stomach contents entering the duodenum.

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Digestive enzymes

Enzymes secreted by the pancreas to break down fats, proteins, and carbohydrates.

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Pancreatic duct system

A series of ducts that transport pancreatic secretions to the intestine, including intercalated and interlobular ducts.

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Hormonal regulation

The primary method of regulating pancreatic secretion through hormones rather than nerves.

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Study Notes

Overview

  • The liver, gallbladder, and pancreas are accessory digestive organs located outside of the digestive tube.
  • The common bile duct from the liver and the main pancreatic duct from the pancreas join to form a single duct.
  • The gallbladder joins the common bile duct via the cystic duct.

Liver

  • Functions:
    • Metabolic factory: synthesizes and breaks down various substances
    • Site of glycogenesis, glycogenolysis, and synthesis of other proteins.
    • Detoxification of many drugs and other poisons.
  • Major aspects:
    • Blood supply: hepatic portal vein (75%) and hepatic artery (25%)
    • Formation and secretion of bile
    • Storage of glycogen, triglycerides, and cholesterol
    • Synthesis of urea and proteins
    • Metabolism of cholesterol and fat
    • Detoxification of many drugs and poisons
    • Cleans bacteria from the blood
  • Cellular components:
    • Hepatocytes (80% of liver mass): polygonal cells joined in anastomosing plates, involved in metabolic activities.
    • Kupffer cells: macrophages in sinusoids, responsible for engulfing bacteria.
    • Fat-forming cells/Ito cells/stellate cells

Pancreas

  • The pancreas is a lobulated structure.
  • Two portions:
    • Exocrine portion: produces pancreatic juice (~1.2L daily) essential for fat, CHO, and protein digestion.
      • Acinar tissue: makes up most of the exocrine portion; contains pyramidal cells containing zymogen granules (inactive enzymes).
      • Duct system: tubules (intercalated, intralobular, and interlobular ducts) transporting secretions.
    • Endocrine portion: produces hormones regulating CHO metabolism (eg. insulin, glucagon); consists of islets of Langerhans.

Gallbladder

  • Pear-shaped organ storing and concentrating bile.
  • Wall layers: mucosa (simple columnar epithelium), lamina propria (loose connective tissue), muscularis externa (smooth muscle), serosa (connective tissue).
  • Contains Rokitansky-Aschoff sinuses in the mucosa.
  • Luschka ducts are peculiar duct-like structures found on the hepatic surface, near the neck of the gallbladder.

Biliary Tree

  • Composed of:
    • Right hepatic duct
    • Left hepatic duct
    • Common hepatic duct
    • Cystic duct
    • Common bile duct
    • Pancreatic duct
    • Sphincter of Oddi

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