Comprehensive Notes on Pancreas Anatomy, Function, and Diseases

Pancreas Anatomy

• The pancreas is located near the duodenum of the small intestine.
• It receives the bile duct from the gall bladder, which merges into the common bile duct.
• The pancreas is associated with the splenic artery and spleen.
• The pancreas has both exocrine and endocrine functions, carried out by different types of cells.

Pancreas: Cells and Functions

• Acinar cells (exocrine): Secrete digestive enzymes.
• Pancreatic islets (Islets of Langerhans) (endocrine):
  • α cells: Produce glucagon.
  • β cells: Produce insulin.

Function of Pancreas

• Endocrine Function (Islets of Langerhans):
  • Regulates blood sugar levels through insulin and glucagon.
• Exocrine Function (Acinar cells and ducts):
  • Produces pancreatic juice, which contains:
    • Bicarbonate: Neutralizes acidic chyme from the stomach.
    • Pancreatic proteases: Released as zymogens (inactive precursors) and activated in the duodenum.
    • Amylase, lipases, nucleases: Digestive enzymes that break down carbohydrates, fats, and nucleic acids, respectively.

Hormonal Control of Pancreatic Juice Secretion

• Secretin:
  • Stimulates the release of digestive enzymes from acinar cells.
• CCK (Cholecystokinin):
  • Stimulates the secretion of bicarbonate from duct cells.

Hormones of the Pancreas

• Insulin:
  • Receptor: Receptor Tyrosine Kinase (RTK).
  • General effect: Decreases blood glucose levels.
  • Mechanism:
    • $\uparrow$ Glucose uptake by cells.
    • $\uparrow$ Glycogenesis (conversion of glucose to glycogen).
    • $\downarrow$ Glycogenolysis (breakdown of glycogen to glucose).
    • $\uparrow$ Glucose conversion to fat.
• Glucagon:
  • Receptor: G-Protein Coupled Receptor (GPCR).
  • General effect: Increases blood glucose levels.
  • Mechanism:
    • $\,\downarrow$ Conversion of glucose to glycogen (\downarrow Glycogenesis).
    • $\uparrow$ Glycogenolysis (breakdown of glycogen to glucose).
• Somatostatin:
  • Inhibits the release of both insulin and glucagon.

Role of the Nervous System

• Innervation of the Islets of Langerhans:
  • Parasympathetic nervous system:
    • Stimulates the release of insulin.
    • Inhibits the release of glucagon.
  • Sympathetic nervous system:
    • Stimulates the release of glucagon.
    • Inhibits the release of insulin.

Diabetes Mellitus (DM)

• Caused by:
  • Lack of insulin.
  • Lack of response to insulin.
• Type 1 DM:
  • Pancreas does not release insulin (Primary Endocrinopathy).
  • Treatment: Insulin injections.
• Type 2 DM:
  • Cells do not respond to insulin (Non-insulin dependent diabetes, Other Endocrinopathy).
  • Treatment: Lifestyle changes (diet and exercise).

Other Types of Diabetes

• Gestational Diabetes (GDM):
  • Occurs in pregnant women.
  • Increases the risk of developing diabetes later in life.
• Diabetes Insipidus:
  • Lack of ADH (Anti-Diuretic Hormone).
  • Symptoms: Excessive thirst (polydipsia), excessive urination (polyuria), dilute urine.
  • Causes:
    • Neurogenic: Lack of ADH production in the hypothalamus (Tertiary).
    • Nephrogenic: Kidneys do not respond to ADH (Other endocrinopathy).
    • Dipsogenic: Damage to the thirst mechanism in the hypothalamus (Tertiary).

Other Diseases

• Hyperinsulinism:
  • Damage to islets of Langerhans, causing overproduction of insulin.
  • Leads to: Nervous system deprivation of glucose resulting in anxiety, nervousness, coma, and sweating.
  • Treatment: Administration of glucose and glucagon.
• Pancreatitis:
  • Inflammation of the pancreas.
  • Causes: Gallstones (acute) or alcohol (chronic).

Pancreatic Cancer

• Exocrine:
  • Usually starts from duct epithelium.
• Neuroendocrine:
  • Pancreatic Neuroendocrine Tumor (PaNETs).
  • Can be functioning (produce excess hormones) or non-functioning (do not produce excess hormones).
  • Often diagnosed late, resulting in a high mortality rate.