H. pylori Overview

• H. pylori (Helicobacter pylori): A gram-negative bacterium associated with gastric mucosa.

Gastric Pits and Secretory Cells

• Gastric Pits: Invaginations in the stomach lining containing various secretory cells.

  • Parietal Cells:

    • Secrete Hydrochloric Acid (HCl) and Intrinsic Factor.

  • Chief Cells:

    • Produce Pepsinogen, which is converted to Pepsin by HCl to digest proteins.

  • Enterochromaffin-like Cells:

    • Secrete Histamine, which stimulates parietal cells to release HCl.

  • G Cells:

    • Secrete Gastrin, a hormone that stimulates acid production and triggers enteroendocrine cells to release other hormones.

Gastrin's Role

• Gastrin stimulates:

  • Parietal Cells: Increase HCl production.

  • Enterochromaffin-like Cells: Release additional hormones leading to more HCl secretion.

  • Chief Cells: Enhances pepsin production.

Antiemetics

• Familiarize with common antiemetics and their classes, as they will appear on tests.

Nutrient Flow to the Liver

• Portal Vein: Brings nutrients and deoxygenated blood from the intestines to the liver.

• Inferior Vena Cava:

  • Collects blood from the liver to return it to the heart, entering through the right atrium.

Cytochrome P450 Enzyme

• CYP 3A4:

  • Important cytochrome P450 enzyme involved in phase 1 metabolism for over 50% of drugs.

  • Operates in the smooth endoplasmic reticulum of hepatocytes, adding polar groups to drugs.

Intestinal Hormones

• GLP-1 (Glucagon-like peptide-1) and GIP (Glucose-dependent insulinotropic peptide):

  • Both are incretins that stimulate insulin production and release from the pancreas.

  • Short-lived naturally, but extended through pharmacological modulation.

Bile Acids and Fats

• Bile Acids/Bile Salts:

  • Derived from cholesterol; composed of hydroxyl groups and a steroid backbone.

Gastroesophageal Reflux Disease (GERD)

• GERD occurs due to:

  • Insufficient closure of the lower esophageal sphincter, allowing gastric acid to enter the esophagus, causing heartburn.