L4 (T1): Thyroid Hormone Physiology
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Questions and Answers

Which of the following is responsible for actively transporting thyroid hormones across the cell membrane?

  • G protein coupled receptor
  • Receptor tyrosine kinases
  • Transmembrane transporter (correct)
  • None of the above

    • What is the main function of hormone-receptor complexes formed by thyroid hormones and intracellular Thyroid Receptors (TRα/TRβ)?

  • Inhibit gene expression
  • Promote gene expression (correct)
  • Activate G protein signaling
  • Block transcription factors

    • Which of the following is a symptom of hyperthyroidism?

  • Tiredness
  • Protruding eyes (correct)
  • Decreased body temperature
  • Weight gain

    • Which of the following can lead to hypo- and hyper-thyroidism?

    <p>All of the above</p> Signup and view all the answers

    Which of the following is a long-term effect associated with hypothyroidism?

    <p>Cardiovascular disease</p> Signup and view all the answers

    Which hormone is Levothyroxine, a treatment for hypothyroidism, a synthetic analogue of?

    <p>T4</p> Signup and view all the answers

    Which gland secretes hormones that impact the health and disease of the thyroid?

    <p>Pituitary gland</p> Signup and view all the answers

    What is the main function of the thyroid gland?

    <p>Producing thyroid hormones</p> Signup and view all the answers

    Which part of the body is responsible for the synthesis of thyroid hormones T3 and T4?

    <p>Thyroid gland</p> Signup and view all the answers

    What is the role of the hypothalamic-pituitary-thyroid feedback loops in thyroid hormone physiology?

    <p>Maintaining hormone balance</p> Signup and view all the answers

    What is the purpose of the lecture on thyroid hormone physiology?

    <p>To study the impact of thyroid hormones on health and disease</p> Signup and view all the answers

    What is the function of the thyroid hormone circulation?

    <p>Transporting thyroid hormones in the body</p> Signup and view all the answers

    Which artery does the inferior thyroid artery branch from?

    <p>Subclavian</p> Signup and view all the answers

    Which vein does the superior thyroid vein drain to?

    <p>Internal jugular vein</p> Signup and view all the answers

    Which nerve innervates the larynx?

    <p>Recurrent laryngeal nerve</p> Signup and view all the answers

    Where does the initial lymphatic drainage of the thyroid go?

    <p>Prelaryngeal, pretracheal and paratracheal nodes</p> Signup and view all the answers

    Which cells are responsible for the uptake of iodide and secretion of thyroid hormones?

    <p>Follicular cells</p> Signup and view all the answers

    Which step in thyroid hormone synthesis involves iodotyrosil coupling?

    <p>Iodination</p> Signup and view all the answers

    Which chapter provides a more in-depth coverage of the material discussed in the lecture?

    <p>Chapter 7</p> Signup and view all the answers

    Which edition of the book is mentioned in the text?

    <p>Tenth Edition</p> Signup and view all the answers

    Which publisher published the book mentioned in the text?

    <p>McGraw-Hill Medical</p> Signup and view all the answers

    What is the ISBN of the book mentioned in the text?

    <p>978-0071622431</p> Signup and view all the answers

    Where can you find a feedback questionnaire for this lecture?

    <p>Follow the link below</p> Signup and view all the answers

    How long does it take to complete the feedback questionnaire?

    <p>2 minutes</p> Signup and view all the answers

    Which step of thyroid hormone synthesis involves the production of thyroglobulin?

    <p>Iodination</p> Signup and view all the answers

    Which step of thyroid hormone synthesis involves the coupling of iodotyrosil residues to form monoiodotyrosil (MIT) or di-iodotyrosil (DIT)?

    <p>Iodotyrosil Coupling to form T3 &amp; T4</p> Signup and view all the answers

    Which step of thyroid hormone synthesis involves the breakdown of thyroglobulin, releasing T3 and T4?

    <p>Colloidal Storage</p> Signup and view all the answers

    Which enzyme is responsible for the coupling of iodotyrosil residues during thyroid hormone synthesis?

    <p>Thyroid peroxidase (TPO)</p> Signup and view all the answers

    Which form of thyroid hormone is considered metabolically inactive?

    <p>T4</p> Signup and view all the answers

    Which step of thyroid hormone synthesis does thyroid peroxidase (TPO) NOT participate in?

    <p>Breakdown of TG, releasing T3 &amp; T4</p> Signup and view all the answers

    What is the primary focus of this section on thyroid hormones?

    <p>To understand the normal physiology of the thyroid axis</p> Signup and view all the answers

    What distinguishes thyroid hormones from other hormones?

    <p>They are synthesized differently from other hormones</p> Signup and view all the answers

    What will be covered in this section on thyroid hormones?

    <p>Thyroid physiology and hormone synthesis</p> Signup and view all the answers

    What is the learning outcome of this section on thyroid hormones?

    <p>To understand the normal physiology of the thyroid axis</p> Signup and view all the answers

    Which artery supplies blood to the superior part of the thyroid gland?

    <p>External carotid artery</p> Signup and view all the answers

    What is the main venous drainage pathway for the inferior thyroid gland?

    <p>Brachiocephalic vein</p> Signup and view all the answers

    Which nerve is responsible for innervating the thyroid gland?

    <p>Vagus nerve</p> Signup and view all the answers

    What is the function of the recurrent laryngeal nerve?

    <p>Controlling the larynx during speech</p> Signup and view all the answers

    Which nerve is potentially damaged during thyroid surgery?

    <p>Recurrent laryngeal nerve</p> Signup and view all the answers

    Why is it important to check the lymph nodes if thyroid cancer is suspected?

    <p>Thyroid cancer can metastasize to the lymph nodes</p> Signup and view all the answers

    Where does the lymphatic drainage from the thyroid primarily occur?

    <p>Pre laryngeal, pre tracheal, and para tracheal nodes</p> Signup and view all the answers

    What is the main function of the follicular cells in the thyroid?

    <p>Synthesis and secretion of thyroid hormones</p> Signup and view all the answers

    Which enzyme is responsible for the breakdown of thyroglobulin and the release of T3 and T4?

    <p>Thyroid peroxidase (TPO)</p> Signup and view all the answers

    What is the predominant form of thyroid hormone released into the blood?

    <p>T4</p> Signup and view all the answers

    Which enzyme is responsible for the conversion of T4 to T3?

    <p>13-diodinase</p> Signup and view all the answers

    What is the main reason for the conversion of T4 to T3 in the tissues?

    <p>To increase metabolic rate</p> Signup and view all the answers

    Which proteins act as carrier proteins for thyroid hormones?

    <p>Globulin, pre-albumin, and albumin</p> Signup and view all the answers

    How do bound thyroid hormones differ from free thyroid hormones?

    <p>Bound thyroid hormones are inactive, while free thyroid hormones are biologically active</p> Signup and view all the answers

    How do thyroid hormones move through the body?

    <p>They are actively transported across the cell membrane</p> Signup and view all the answers

    How are thyroid hormones different from steroid hormones in terms of membrane passage?

    <p>Steroid hormones pass freely through the membrane, while thyroid hormones require a carrier protein</p> Signup and view all the answers

    Which major artery does the inferior thyroid artery branch from?

    <p>Subclavian artery</p> Signup and view all the answers

    What is the name of the protein produced by the Golgi and pushed out into the colloid?

    <p>Thyroid globulin</p> Signup and view all the answers

    What is the function of thyroid peroxidase (TPO) in the synthesis of thyroid hormones?

    <p>Converts iodide into iodine and sticks iodine residues onto thyroid globulin</p> Signup and view all the answers

    What is the product of coupling of iodotyrosil residues by TPO during thyroid hormone synthesis?

    <p>Monoiodotyrosil (MIT) and di-iodotyrosil (DIT)</p> Signup and view all the answers

    Which of the following is true about thyroid hormones and steroid hormones?

    <p>Thyroid hormones cannot pass through the membrane on their own, while steroid hormones can.</p> Signup and view all the answers

    What is the role of a transmembrane transporter in the passage of thyroid hormones across the membrane?

    <p>It helps thyroid hormones get across the membrane.</p> Signup and view all the answers

    What happens to thyroid hormones once they are across the membrane?

    <p>They act like steroid hormones.</p> Signup and view all the answers

    Why can't thyroid hormones pass through the membrane on their own?

    <p>They have a negative charge.</p> Signup and view all the answers

    What is the difference between thyroid hormones and thyroid globulin in terms of membrane passage?

    <p>Thyroid hormones can pass through the membrane on their own, while thyroid globulin cannot.</p> Signup and view all the answers

    What is the main reason why thyroid hormones require a transmembrane transporter for membrane passage?

    <p>They have a negative charge.</p> Signup and view all the answers

    Study Notes

    Thyroid Hormone Transport and Function

    • Transmembrane transporters are crucial for actively transporting thyroid hormones across the cell membrane.
    • Hormone-receptor complexes formed by thyroid hormones and intracellular thyroid receptors (TRα/TRβ) regulate gene expression, influencing metabolism and development.
    • Hyperthyroidism symptoms include weight loss, increased heart rate, and anxiety.
    • Causes of hypo- and hyperthyroidism include autoimmune diseases, iodine deficiency, and medication side effects.
    • Long-term effects associated with hypothyroidism can lead to developmental delays and cognitive impairments in children.

    Hormone Treatments and Glands

    • Levothyroxine, a synthetic analogue of thyroxine (T4), is used to treat hypothyroidism.
    • The pituitary gland regulates thyroid function by secreting Thyroid Stimulating Hormone (TSH).

    Thyroid Gland Functions and Physiology

    • The main function of the thyroid gland is to synthesize and release thyroid hormones T3 (triiodothyronine) and T4 (thyroxine).
    • Synthesis of thyroid hormones occurs primarily in the follicular cells of the thyroid gland.

    Regulation and Feedback Mechanisms

    • Hypothalamic-pituitary-thyroid feedback loops regulate thyroid hormone levels, maintaining homeostasis.
    • Circirculation of thyroid hormones ensures their distribution and action throughout the body.

    Blood Supply and Innervation

    • The inferior thyroid artery typically branches from the thyrocervical trunk, supplying the thyroid gland.
    • The superior thyroid vein drains into the internal jugular vein.
    • The recurrent laryngeal nerve innervates the larynx, controlling vocal cord function; it is at risk during thyroid surgery.

    Lymphatic Drainage and Cancer Considerations

    • Initial lymphatic drainage from the thyroid goes to the deep cervical lymph nodes.
    • Checking lymph nodes is crucial when thyroid cancer is suspected to assess the spread of malignancy.

    Hormone Synthesis and Iodine Uptake

    • Follicular cells uptake iodide and are responsible for secreting thyroid hormones.
    • Thyroid hormone synthesis involves iodotyrosil coupling, where iodotyrosil residues couple to form MIT or DIT.
    • Breakdown of thyroglobulin releases T3 and T4, catalyzed by specific enzymes, primarily thyroid peroxidase (TPO).

    Metabolism and Conversion of Thyroid Hormones

    • T4 is the predominant form of thyroid hormone in the bloodstream but is metabolically inactive; it is converted to the active T3 form in tissues.
    • Conversion of T4 to T3 allows for proper metabolic functioning and regulation in target cells.

    Transport Proteins and Membrane Passage

    • Carrier proteins, such as thyroxine-binding globulin (TBG), transport thyroid hormones in the bloodstream.
    • Bound thyroid hormones remain inactive, while free hormones can actively exert biological effects.

    Differences in Hormone Transport

    • Thyroid hormones require transmembrane transporters due to their inability to pass through the lipid bilayer independently, differing from steroid hormones that can freely diffuse.
    • Thyroid hormones are generated and secreted in inactive forms, necessitating conversion and transport via specialized proteins for functionality.

    Feedback and Learning Outcomes

    • This section of study focuses on understanding thyroid hormone physiology, their synthesis, function, and the regulatory mechanisms involved.
    • Students are expected to grasp the significance of maintaining thyroid hormone levels within normal physiological ranges for overall health.

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    Related Documents

    Thyroid Hormone Physiology - Student Copy(1).pptx

    Description

    Test your knowledge on peripheral conversions, iodide uptake, follicular cells, and thyroglobulin with this quiz. Explore topics such as T4, T3, colloid, and iodination to enhance your understanding of thyroid function.

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