Thyroid Gland and Hormones

Overview

• Continuation of the biology playlist.
• Focus on thyroid gland and hormones (T3 and T4).
• T4 is more abundant; T3 is more active.
• Thyroid hormones boost metabolic rate.

Endocrine System Hierarchy

• CEO: Hypothalamus
• General Manager: Pituitary Gland
• Employees: Thyroid, Adrenal Cortex, Gonads
• Independent Contractors: Parathyroid, Adrenal Medulla, Pancreas

Hormonal Pathway

• Hypothalamus: Secretes TRH (Thyrotropin Releasing Hormone)
• Anterior Pituitary: Secretes TSH (Thyroid Stimulating Hormone)
• Thyroid Gland: Secretes T3 and T4

Regulation

• Negative feedback prevents excessive thyroid hormone production.
• Excess thyroid hormone inhibits TRH and TSH.

Hypothyroidism

• Causes:
  • Primary: Thyroid gland issue
  • Secondary: Anterior pituitary issue
  • Tertiary: Hypothalamus issue
• Symptoms: Low metabolic rate, tiredness, depression, obesity, constipation

Thyroid Hormone Synthesis

• Raw Materials: Tyrosine and Iodine
• Processes:
  • Oxidation
  • Organification
  • Coupling
• Key Enzyme: Thyroperoxidase

Sources

• Tyrosine: Synthesized from phenylalanine, obtained from protein-rich foods.
• Iodine: Sourced from seafood or iodized salt.

Thyroid Gland Anatomy

• Located in the neck.
• Contains follicles and parafollicular cells.
• Follicles: Produce thyroid hormones (A cells).
• Parafollicular Cells (C cells): Produce calcitonin.

Functions of Thyroid Hormone

• Increases metabolic rate and body temperature.
• Supports brain development and growth.
• Enhances catecholamines activity.
• Increases gastrointestinal motility.

Comparison of Hypothyroidism and Hyperthyroidism

• Hypothyroidism:
  • Bradycardia, cold intolerance, constipation, weight gain, depression
• Hyperthyroidism:
  • Tachycardia, heat intolerance, diarrhea, weight loss, anxiety

Diagnosis

• Visual comparison can indicate changes due to thyroid issues.

Additional Information

• Thyroid hormone participates in the glucagon world (catabolic activity).
• Issues can affect fertility and menstrual regularities.

Study Resources

• Check out related courses on renal physiology and endocrine pharmacology for further learning.

• Remember to subscribe for more educational content.