Pancreas: Anatomy & Physiology

Anatomy

Embryology

  • Ventral Bud: Uncinate & Inferior Head
  • Dorsal Bud: Head, Body & Tail

Structure

  • Parts:
    • Uncinate Process
    • Head
    • Body
    • Tail
  • Anterior to SMA/SMV
    • Uncinate Process Wraps Behind
  • Ducts Mn
    • Duct of Wirsung
      • Primary Duct with Major Papilla
      • Combines with CBD
    • Duct of Santorini
      • Accessory Duct with Minor Papilla
      • Direct to Duodenum

Blood Supply

  • Arterial Supply
    • Head
      • Superior Pancreaticoduodenal Arteries (GDA)
      • Inferior Pancreaticoduodenal Arteries (SMA)
    • Body & Tail
      • Pancreatic Branches (Off Splenic Artery)
        • Great (Largest), Dorsal, Inferior & Caudal
  • Venous Return
    • Splenic & SMV (Portal System)

Lymphatics

  • By the Celiac & SMA Nodes

Pancreas 1

Pancreas Ductal System

Pancreas Blood Supply 1

Physiology

Exocrine Function

  • GI Hormones
  • Ductal Cells: Secrete HCO3
  • Acinar Cells: Secrete Digestive Enzymes
    • Secreted in Active Form
      • Amylase
        • Function: Digest Saccharides
        • Fastest to Be Cleared in Pancreatitis Mn
      • Lipase
        • Function: Digest Lipids
        • Most Specific Enzyme
    • Secreted in Inactive Form (Zymogens)
      • Trypsinogen
        • Converted to Active Trypsin by Enterokinase on the Intestinal Brush Border
        • Trypsin Function: Activates Other Pancreas Enzymes
      • Chymotrypsinogen
        • Converted to Active Chymotrypsin by Trypsin
        • Chymotrypsin Function: Digest Protein

Endocrine Function – Islet of Langerhans

  • Alpha (α) Cells
    • In Islet Periphery; 20% of Mass
    • Secrete: Glucagon
      • Function: Increases Glucose & Decrease Acid Secretion
    • Stimulated By: Low Glucose
  • Beta (β) Cells
    • At Islet Center; 70% of Mass
    • Secrete: Insulin
      • Function: Decrease Glucose
        • Increase Glucose Uptake in Muscle and Adipose Tissue
        • Increase Lipogenesis, Decreases Lipolysis
        • Increases Glycogenosis, Decreases Glycogenolysis
        • Decreases Gluconeogenesis
    • Stimulated By: Glucose & Fatty Acids
    • Insulin Response to Oral Glucose is Greater than to IV Glucose
      • Due to the “Incretin Effect” – The Augmentation of Insulin Secretion After Oral as Opposed to IV Administration of Glucose
      • Directly Mediated by Glucagon-Like Peptide-1 (GLP-1) & Glucose-Dependent Insulinotropic Polypeptide (GIP)
  • Delta (Δ) Cells
  • Epsilon (ε) Cells
  • PP Cells (F Cells)
    • Secrete: Pancreatic Polypeptide
      • Function: Decrease GB & Pancreas Secretion
  • G Cells
    • Secrete: Gastrin
    • Normally Not Present Except in Gastrinoma
  • Also Secreted:
    • Vasoactive Intestinal Polypeptide (VIP)
      • Secreted by Neurons
      • Function: Intestinal Secretion & Motility
    • Serotonin

Mnemonics

Pancreatic Ducts

  • Wirsung – Aggressive (Major/Primary)
    • Wirsung was a German Anatomist
    • Wir-War: Germany was Aggressive and Always at War
  • Santorini – Relaxed (Minor/Accessory)
    • Santorini is a Relaxed Pacifist Island

Amylase vs Lipase Clearance

  • A – First Letter (Amylase) is First Cleared

References

  1. Gray H. Anatomy of the Human Body (1918). Public Domain.