Updated: 12/22/2021

Thyroid Physiology

0%
Topic
Review Topic
0
0
N/A
N/A
Questions
1
0
0
Topic
  • Introduction
    • The thyroid produces hormones that contain iodine
      • T4 is converted to active T3 and inactive reverse T3 (rT3) in peripheral tissue
      • T3 is more potent than T4
      • rT3 is inactive
      • the thyroid controls the body’s metabolic rate
  • Physiology
    • Functions of T3
      • Brain maturation
      • Bone growth
      • Beta-adrenergic
      • Basal metabolic rate
      • Blood glucose
      • Breakdown lipids (↑ lipolysis)
    • Synthesis
      • synthesized in thyroid gland and stored in follicles
      • thyroid peroxidase catalyzes oxidation, organification, and coupling
      • T4 is converted to rT3 via 5'-deiodinase, which removes an iodine from the inner ring of T4
      • T4 is converted to T3 in peripheral tissues via 5’-deiodinase, which removes an iodine from the outer ring of T4
        • inhibited by steroids, beta-blockers, and propylthiouracil
    • Regulation of thyroid hormones
      • production of thyroid hormones
        • thyrotropin-releasing hormone (TRH) release from the hypothalamus stimulates thyroid-stimulating hormone (TSH) release from the pituitary gland
        • TSH then stimulates thyroid follicular cells to produce T3/T4
        • In cases of papillary thyroid carcinoma, patients are often treated with levothyroxine after thyroidectomy such that TSH levels are suppressed, in order to prevent TSH stimulation of any remaining malignant cells
      • negative feedback loop
        • free T3/T4 causes ↓ TRH secretion and ↓ sensitivity of pituitary to TRH
      • bound T3/T4 are inactive
        • thyroxine-binding globulin (TBG) binds to T3/T4, making them inactive

Please rate this review topic.

You have never rated this topic.

Thank you. You can rate this topic again in 12 months.

Flashcards (0)
Cards
1 of 0
Questions (1)
Question locked
Sorry, this question is for
PEAK Premium Subscribers only
Upgrade to PEAK
VIDEOS & PODCASTS (1)
EXPERT COMMENTS (0)
Private Note