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Thyroid Anatomy
Aka: Thyroid Anatomy, Thyroid Physiology, Thyroid
- Images

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Embryology
- Develops from Tongue root (foramen cecum)
- Formed by 5th-6th week of development
- Anatomy
- Normal Adult Thyroid weighs 20-25g
- Components
- Two Lateral lobes
- Isthmus centrally connects the lobes
- Near structures
- Recurrent laryngeal nerve
- Parathyroid Glands
- Physiology
- Stressors stimulate increased Thyroid function
- Puberty
- Pregnancy
- Physiologic stress
- Hypothalamus
- Thyrotropin Releasing Hormone (TRH) released
- TRH passes down pituitary stalk to pituitary
- Anterior Pituitary
- Thyroid Stimulating Hormone (TSH) released
- TSH passes into circulation to Thyroid
- Thyroid
- Iodine is absorbed from circulation
- Thyroxine (T4) released into circulation
- Peripheral Tissues
- Triiodothyronine (T3) produced from T4 deiodination
- Circulation
- Thyroid Binding Globulin (TBG) binds T4 and T3
- T4 is 99.96% bound
- T3 is 99.7% bound
- T4 and T3 stimulate all metabolic processes
- T3 is several times more potent than T4
- Feedback Loop
- Increased T4 and T3 levels suppress TRH and TSH