Microscopic Structure of the Alimen-Hepatobiliary System

Alimentary and Hepatobiliary System

  • Mouth (oral cavity)

    • Tongue

    • Pharynx

  • Salivary glands

    • Parotid gland

    • Sublingual gland

    • Submandibular gland

  • Esophagus

  • Stomach

  • Small intestine

    • Duodenum

    • Jejunum

    • Ileum

  • Large intestine

    • Cecum

    • Ascending colon

    • Transverse colon

    • Descending colon

    • Sigmoid colon

    • Rectum

    • Vermiform appendix

    • Anal canal

  • Anus

  • Liver

  • Gallbladder

  • Pancreas

  • (Spleen)

Table 15-2: Summary of Distinguishing Digestive Tract Features

  • Region and Subdivisions

    • Esophagus (upper, middle, lower)

    • Stomach (cardia, fundus, body, pylorus)

    • Small intestine (duodenum, jejunum, ileum)

  • Mucosa (Epithelium, Lamina Propria, Muscularis Mucosae)

    • Esophagus: Nonkeratinized stratified squamous epithelium; cardiac glands at lower end

    • Stomach: Surface mucous cells and gastric pits leading to gastric glands with parietal and chief cells (in the fundus and body) or to mucous cardiac glands and pyloric glands

    • Small intestine: Plicae circulares; villi, with enterocytes and goblet cells, and crypts/glands with Paneth cells

  • Submucosa (with Submucosal Plexuses)

    • Esophagus: Small esophageal glands (mainly mucous)

    • Stomach: No distinguishing features

    • Small intestine: Duodenal (Brunner) glands (entirely mucous); possible extensions of Peyer patches in ileum

  • Muscularis (Inner Circular and Outer Longitudinal Layers, with Myenteric Plexuses Between Them)

    • Esophagus: Both layers striated muscle in upper region; both layers smooth muscle in lower region; smooth and striated muscle fascicles mingled in middle region

    • Stomach: Three indistinct layers of smooth muscle (inner oblique, middle circular, and outer longitudinal)

    • Small intestine: No distinguishing features

  • Adventitia/Serosa

    • Esophagus: Adventitia, except at lower end with serosa

    • Stomach: Serosa

    • Small intestine: Mainly serosa

Struktur Histologis Duodenum, Jejunum, Ileum

  • Duodenum

    • Submucosal glands

    • Plica

  • Jejunum

    • Plica

    • Villi

  • Ileum

    • Serosa

    • Muscularis externa

    • Submucosa

    • Mucosa

    • Muscularis mucosae

    • Aggregate lymphoid nodules (Peyer's patches)

Hepatobiliary System

Hepar (Liver)

  • See Alimentary and Hepatobiliary System Structure (same image)

  • Left Lobe

  • Right Lobe

  • Falciform Ligament

  • Anterior View of Liver

Overview

  • Upper right quadrant

  • 2 major lobes and 2 smaller lobes

  • 2 blood supply:

    • Hepatic artery

    • Portal vein

Functions

  • Exocrine

    • Primary bile

  • Endocrine

    • Metabolism

    • Detoxification of toxins and drugs

    • Phagocytose blood-borne foreign particulate matter and defunct erythrocytes

    • Transfer IgA from space of Disse into bile canaliculi

    • Vitamin storage (A, D, B12)

Microscopic Structure

  • Capsule: Dense, irregular Connective tissue

  • Parenchyma: Hepatocytes

  • Stroma: Connective tissue

    • Reticular CT

    • Fibroelastic CT

  • Liver → Lobe → Lobule

  • Kuffer cell

Liver Lobules

  • Liver Lobule Cross-Section

    • Bile Ductule

    • Branch of Portal Vein

    • Branch of Hepatic Artery

    • Hepatocyte

    • Central Vein (feeds into hepatic vein)

    • Sinusoid

Liver Structure

  • portal area

  • portal vein

  • hepatic artery

  • bile duct

  • lobule boundary

  • central vein

Concept of Liver Lobules

  • Classical lobule

  • Portal lobule

  • Hepatic/Portal acinus

  • Elements

    • Portal Area (PA)

    • Central Vein (CV)

    • Hepatic artery

    • Bile duct

    • Portal vein

Hepatic/Classic Lobule

  • Anatomical lobule

  • Hepatocytes form irregular plate arranged radially circling central vein

  • Reticular CT as framework, fibroelastic CT as boundaries

  • Surrounded by portal area:

    • Hepatic artery

    • Portal vein

    • Bile duct

Liver Slide

  • Classic liver lobule

  • Portal triad with surrounding connective tissue

  • Central vein

Portal Lobule

  • Functional lobule

  • Region which bile is produced and drained to bile duct

  • Bile: drained from centre to periphery

Liver Slide

  • Portal lobule

  • Three central veins

Hepatic/Portal Acinus

  • Functional lobule: between 2 central veins

  • Center: branch of blood vessel Portal Triad

  • 3 zones:

    • Near the blood vessel/periportal:

      • Gluconeogenesis

      • SER <<

      • Most oxygenated and the first area exposed to nutrient by the portal vessel

    • Middle

      • Glycolysis

      • Lipid metabolism

    • Edge/pericentral

      • Mitochondria >>>

Liver Slide

  • Portal triads

  • Central vein

Hepatocyte

  • Large, cuboidal/polygonal epithelial cell

  • Round central nucleus, binucleated

  • Eosinophilic cytoplasm

  • Space of Disse:

    • Between the sinusoid lining cells and hepatocytes

    • Content:

      • Reticular fibers

      • Blood plasma

      • Fat storing cells/ ito cells

      • Cytoplasmic process of Kupffer cells

Hepatocyte Domains

  • Lateral domain: (between 2 hepatocyte cells)

    • Bile canaliculi

    • Tight junction

    • Gap junction

  • Sinusoidal domain: sinusoid

    • Microvilli protrude to the space of Disse

Kupffer Cell

  • Macrophages

  • Phagocytes cellular debris, especially defunct erythrocytes

  • Attaches at the sinusoidal lining cells (endothelial cells)

Fat-Storing Cells (Ito’s Cells)

  • In the space of Disse

  • Manufacture & release reticular fiber

  • Form Fibrous CT

  • Store Vitamin A

  • Secrete GF, sitokin

Ito's Cells and Kupffer Cell

  • Visual representation of both cell types in the liver.

Liver Regeneration

  • High capacity

  • The liver has a great ability to regenerate after a hepatotoxic insult or even after a portion of the liver is excised.

  • Induced by fat storing cell/ITO cells

Gall Bladder

Gall Bladder Functions

  • Main functions:

    • Bile storage

    • Concentrates bile

    • Transfer bile to cystic duct

  • Bile has function in fat digestion

Microscopic Structure

  • Mucous layer: mucous fold

    • Epithelium: simple columnar epithelium

    • Lamina propria: loose CT, mucous glands at the neck

  • Musculature layer

    • Thin smooth muscle

  • Outer layer:

    • Connective tissue

    • Blood vessels, lymph, nerve

Bile Ducts

  • BILE CANALICULI --- CHOLANGIOLES

  • CANALS OF HERING

  • INTERLOBULAR BILE DUCT

  • RIGHT AND LEFT HEPATIC DUCT

Biliary Tree

  • Includes:

    • Liver

    • Right hepatic duct

    • Left hepatic duct

    • Common hepatic duct

    • Gallbladder

    • Cystic duct

    • Pancreas

    • Common bile duct

    • Pancreatic duct

    • Duodenum

    • Sphincter of Oddi

  • EXTRAHEPATIC DUCT