Thyroid Gland and Pituitary Gland

Pituitary Gland

• Located in the brain, known as the "master gland"
• Produces Thyroid Stimulating Hormone (TSH)

Thyroid Gland

• Located in the neck, attached to the trachea
• Produces thyroxine (T3 and T4)
• Requires iodine from diet for thyroxine production
• Structure contains a precursor called thyroglobulin

Hormones and Their Interaction

• TSH: Produced by pituitary, stimulates thyroid to produce thyroxine
• Thyroxine (T3 and T4): Contains iodine; T3 has 3 iodines, T4 has 4 iodines
• Dietary Iodine: Crucial for thyroxine production, can come from seafood
• Example: Radioactive iodine can be used to destroy thyroid tissue in cancer treatment

Negative Feedback Loop

• Presence of thyroxine in blood regulates TSH production
  • High thyroxine → Low TSH production
  • Low thyroxine → High TSH production
• Hypothyroidism: Diagnosed by elevated TSH
• Hyperthyroidism: Diagnosed by low TSH
• Aka a "negative feedback loop"

Functions of Thyroxine

1. Increase ATP Production: Enhances oxygen and glucose consumption, increases cellular activity
2. Cardiovascular Effects: Increases heart rate and blood pressure
3. Blood Production: Stimulates red blood cell production in bone marrow
4. Brain Activity: Enhances mood, energy, and clarity of thinking

Thyroid Dysfunctions

Hypothyroidism

• Causes: Imbalances post-pregnancy, autoimmune diseases (e.g., Hashimoto's)
• Symptoms:
  • Brain: Foggy thinking, depression, low energy
  • Heart: Low heart rate, low blood pressure
  • Red Blood Cells: Anemia, feeling cold, pallor, fatigue
  • Metabolism: Overweight, tiredness, low ATP production

Hyperthyroidism

• Causes: Autoimmune diseases (e.g., Graves' disease), thyroid cancer
• Symptoms:
  • Brain: Agitation, irritability
  • Heart: Rapid heart rate, high blood pressure, exophthalmos (eye protrusion)
  • Red Blood Cells: May cause polycythemia (though not typical term), feeling hot, flushed
  • Metabolism: Weight loss, restlessness

Diagnosis and Treatment

• Diagnosis: TSH Levels
  • Elevated TSH: Typically indicates hypothyroidism
  • Low TSH: Typically indicates hyperthyroidism
• Treatment: Radioactive Iodine
  • Used to kill thyroid cells in cancer or severe hyperthyroidism cases

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