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Thyroid Gland and Thyroid Hormones
Jun 28, 2024
Thyroid Gland and Thyroid Hormones
Introduction
Discussing the thyroid gland and its hormones (T3 and T4).
T4
: More abundant.
T3
: More active.
Thyroid hormone increases metabolic rate.
Hormonal Hierarchy
Hypothalamus (CEO)
: Secretes TRH (Thyrotropin Releasing Hormone).
Pituitary (General Manager)
: Secretes TSH (Thyroid Stimulating Hormone) upon TRH stimulation.
Thyroid Gland (Employee)
: Secretes T3 and T4 in response to TSH.
Independent Contractors
: Parathyroid, adrenal medulla, and pancreas.
Negative Feedback Mechanism
High thyroid hormone levels inhibit TRH from the hypothalamus and TSH from the anterior pituitary.
Hypothyroidism
Symptoms
: Low metabolic rate, tiredness, laziness, depression, obesity, constipation.
Categories
:
Primary Hypothyroidism
: Problem in the thyroid gland.
Secondary Hypothyroidism
: Problem in the anterior pituitary.
Tertiary Hypothyroidism
: Problem in the hypothalamus.
Raw Materials for Thyroid Hormone
Tyrosine
: Derived from phenylalanine (obtained from foods).
Iodine
: Obtained from diet (e.g., iodized salt, sea food).
Thyroid Gland Anatomy
Located in the neck.
Near the arch of the aorta.
Secretes T4, T3, reverse T3, calcitonin.
Thyroid Follicles
: Produce thyroid hormone.
Para-follicular (C) Cells
: Produce calcitonin.
Thyroid Hormone Production
Iodide Trapping
: Iodide from the bloodstream enters the thyroid gland.
Oxidation
: Iodide converted to iodine.
Organification
: Iodine binds with thyroglobulin (contains tyrosine) to form MIT and DIT.
Coupling
: MIT + DIT = T3, DIT + DIT = T4.
Release
: T3 and T4 released into the bloodstream.
Enzyme
: Thyroperoxidase is essential for oxidation, organification, and coupling.
Effects of TSH
Stimulates thyroid hormone synthesis and enlarges thyroid gland (goiter).
Metabolism
Thyroid Hormone
: Increases basal metabolic rate, protein catabolic, glycogen catabolic, triglycerides catabolic.
Role in Brain Development
: Essential during embryology and childhood.
Catecholamines
: Increases beta-receptor sensitivity.
Reproductive Health
: Boosts ovarian cycle in females, spermatogenesis in males.
Gastrointestinal Motility
: Too much = diarrhea, too little = constipation.
Hyperthyroidism vs Hypothyroidism Symptoms
Hypothyroidism
: Bradycardia, cold intolerance, constipation, coarse hair, depression, dry skin, lethargy, weight gain.
Hyperthyroidism
: Tachycardia, nervousness, heat intolerance, diarrhea, silky hair, weight loss, goiter, exophthalmus.
Diagnosing hyperthyroidism: Old vs. current photos.
Practical Recommendations
Focus on symptoms first when learning about thyroid disorders.
Conclusion
Check out additional resources and courses for deeper understanding.
Support and subscribe for more content.
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