Gastrointestinal and Reproductive System Notes

Gastrointestinal Pharmacology

Ulcers and Gastritis

• Aggressive Factors:
  • H. pylori: A bacterium that can damage the stomach lining.
  • NSAIDs: Nonsteroidal anti-inflammatory drugs that can break down the gut lining, leading to peptic ulcers.
  • Acid: Gastric acid, which can damage the stomach lining.
  • Pepsin: An enzyme that breaks down proteins and can contribute to ulcer formation.
  • Smoking: A habit that can exacerbate ulcers.
• Defensive Factors:
  • Mucus: A protective layer that lines the stomach.
  • Bicarbonate: Neutralizes acid in the stomach.
  • Blood flow: Essential for maintaining the health of the stomach lining.
  • Prostaglandins: Lipids that help reduce acid secretion, increase mucus and bicarbonate production, and maintain blood flow.

Parietal Cell Pharmacology

• Parietal Cell: A cell in the stomach that secretes hydrochloric acid (HCl).
• Stimulation of Acid Secretion:
  • Acetylcholine (ACh): Stimulates acid secretion by binding to M3 muscarinic receptors, increasing intracellular calcium (Ca++).
  • Histamine (Hist): Activates H2 receptors, increasing cAMP levels, which in turn activates H+,K+-ATPase.
  • Gastrin (Gast): Also increases acid secretion.
• Inhibition of Acid Secretion:
  • Proton Pump Inhibitors (PPIs): Inhibit the H+,K+-ATPase, the final step in acid production.
  • Misoprostol (PG): A synthetic prostaglandin that inhibits acid secretion.
  • Pirenzepine: Blocks ACh by binding to M3 receptors.
• Neutralization of Acid: Antacids neutralize stomach acid.

Vomiting

• Sensory Input:
  • Sight, smell, and pain can trigger vomiting.
  • Bloodborne emetics and chemotherapy drugs.
  • Vestibular apparatus stimulation (motion sickness).
• Vomiting Center Receptors:
  • 5-HT3 (Serotonin3): Activated by serotonin.
  • DA2 (Dopamine2): Activated by dopamine.
  • NK1 (Neurokinin1): Activated by substance P.
  • M (Muscarinic cholinergic): Activated by acetylcholine.
  • H1 (Histamine1): Activated by histamine.
• Output:
  • The vomiting center sends signals to the stomach, diaphragm, and abdominal muscles to induce vomiting.

Anti-Emetics

• Anti-emetics: Refer to Tables 84.1 and 84.2 for specific drugs.

Reproductive

Hormonal Regulation - Menstrual Cycle

• Average Menstrual Cycle: 28 days.
• Brain-Hypothalamus-Pituitary-Ovary Axis:
  • Hypothalamus produces Gonadotropin-Releasing Hormone (GnRH).
    GNRH \downarrow
  • Pituitary releases Follicle-Stimulating Hormone (FSH) and Luteinizing Hormone (LH).
    FSH \downarrow
    LH \downarrow
  • Ovaries are stimulated by FSH (during the first half of the cycle) and LH (during the second half).
  • Decline in estrogen levels leads to the shedding of the uterus lining (endometrium).
    estrogen \downarrow
• Estrogens: Present in the body at all times, but levels fluctuate.
  • Produced in testes, ovaries and during pregnancy.
• Effects of Estrogen:
  • The lack of estrogen during menopause increases the risk for osteoporosis and cardiovascular disease.
  • Estrogen increases blood coagulation and improves neurological function.
• Considerations for Estrogen Therapy:
  • Use the smallest amount of estrogen for the shortest period of time.
  • Estrogen/progestin are necessary in women with a uterus.
  • Screen for contraindications before giving estrogen.

Contraception

• Nexplanon: Etonogestrel implant (68 mg), a subdermal contraceptive.

  • It does not protect against HIV infection (AIDS) and other sexually transmitted diseases.

• Depo-Provera: Medroxyprogesterone acetate injectable suspension (150 mg) for intramuscular use as a contraceptive.

• Estrogen effects sperm: Estrogen makes it difficult for sperm to penetrate. It can also stops Breast milk production.

Hormonal Drug

• Give to woman who just had a baby has a lower risk.
• May causes depression
• Affects Sperm production, give to woman with menopause to increase sex drive. Give to men to have more red blood cells and hemoglobin.