This is a series diagrams of the hypothalamic-pituitary-thyroid axis. Please modify each diagram to demonstrate the following conditions.Describe the normal feedback loops that regulate the activity of the thyroid gland. What are the physiological actions of thyroid hormones?Use the diagram to demonstrate how the physiological regulation of the system would be influenced by a ectopic tumor the secrets thyroid stimulating hormone. What would be the physiological effects?Diagram how the system would be affected by papillary thyroid cancer? What would be the effects on the person's physiology?Diagram how the system would be influenced by a thyroidectomy? What would be the symptoms of an inadequate hormone replacement therapy? What part of the systems could be used to test the effect of a replacement therapy?
Paraventricular Nucleus of the Hypothalamus
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Scenario 1: Describe the normal feedback loops that regulate the activity of the thyroid gland. What are the physiological actions of thyroid hormones?Thyroid hormones act on intracellular receptors. Hormone receptor complex binds to co-activator proteins that bind to hormone response elements in target cell/genes to trigger hormone response(s). Thyroid hormones determines metabolic rate: increase heart rate, cardiac output, and respiration; increases heat production; and are needed for normal growth and development.
Thyrotropin Releasing Hormone
Thyrotrope
Thyroid Stimulating Hormone
Thyroid gland
T3 & T4
Thyroid hormones act on intracellular receptors. Hormone receptor complex binds to co-activator proteins that bind to hormone response elements in target cell/genes to trigger hormone response(s). Thyroid hormones determines metabolic rate: increase heart rate, cardiac output, and respiration; increases heat production; and are needed for normal growth and development (Shahid et al., updated 2020).
Shahid MA, Ashraf MA, Sharma S. Physiology, Thyroid Hormone. [Updated 2020 May 18]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2020 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK500006/
Scenario 1
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This is a series diagrams of the hypothalamic-pituitary-thyroid axis. Please modify each diagram to demonstrate the following conditions.
Scenario 1. Diagram the normal feedback loops that regulate the activity of the thyroid gland. What are the physiological actions of thyroid hormones?
Scenario 2. Use the diagram to demonstrate how the physiological regulation of the system would be influenced by a ectopic tumor the secrets thyroid stimulating hormone. What would be the physiological effects?
Scenario 3. Diagram how the system would be affected by papillary thyroid cancer? What would be the effects on the person's physiology?
Scenario 4. Diagram how the system would be influenced by a thyroidectomy and hormone replacement therapy? What would the advantages of staging hormone replacement therapy based on circulating TSH versus the physiological actions of thyroid hormones? What be the advantages of staging the therapy on the physiological effects that the patent is having?
Scenario 2
Scenario 3
Scenario 4
Paraventricular nucleus of the Hypothalamus
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Scenario 4: Diagram how the system would be influenced by a thyroidectomy? What would be the symptoms of an inadequate hormone replacement therapy? What part of the systems could be used to test the effect of a replacement therapy?
Paraventricular Nucleus of the Hypothalamus
r
Scenario 3: Diagram how the system would be affected by papillary thyroid cancer? What would be the effects on the person's physiology?
Paraventricular Nucleus of the Hypothalamus
r
Scenario 2: Use the diagram to demonstrate how the physiological regulation of the system would be influenced by a ectopic tumor the secrets thyroid stimulating hormone. What would be the physiological effects?
Thyrotropin Releasing Hormone
Thyrotropin Releasing Hormone
Thyrotrope Tumor
Thyrotropes
Thyrotropes
Thyroid gland
Thyrotropin Releasing Hormone
Thyroid Stimulating Hormone
Thyroid gland Tumor
Swelling
Thyroid Stimulating Hormone
Thyroid Stimulating Hormone
T3 & T4
T3 & T4
Papillary thyroid carcinoma is an epithelial malignancy. T3 and T4 promotes the proliferation of cancerous cells, and the T3 and T4 levels are usually normal in patients with a untreated papillary thyroid cancer (Krashin et al., 2019).
Krashin, E., Piekiełko-Witkowska, A., Ellis, M., & Ashur-Fabian, O. (2019). Thyroid Hormones and Cancer: A Comprehensive Review of Preclinical and Clinical Studies. Frontiers in endocrinology, 10, 59. https://doi.org/10.3389/fendo.2019.00059
Exogenous T3 & T4
Thyroidectomy is the removal part or all of the thyroid gland. Once removed, the levels of endogenous T3 and T4 made by the thyroid gland decrease and patient needs exogenous T3 and T4 replacement to maintain body functions that otherwise would be compromised for the loss of thyroid hormones. Insufficient hormone replacement treatment can lead to symptoms of hypothyroidism: fatigue, hair loss, dry/rough skin, etc (Schaffler A., 2010) (Hannoush & Weiss, 2016). To test the effect of the hormone replace therapy, the blood of the patient can be tested. The blood can reveal the circulating concentration of TSH and thyroid hormones (according to Hopkinsmedicine.org).
1. Hannoush, Z. C., & Weiss, R. E. (2016). Thyroid Hormone Replacement in Patients Following Thyroidectomy for Thyroid Cancer. Rambam Maimonides medical journal, 7(1), e0002. https://doi.org/10.5041/RMMJ.10229 2. Schäffler A. (2010). Hormone replacement after thyroid and parathyroid surgery. Deutsches Arzteblatt international, 107(47), 827–834. https://doi.org/10.3238/arztebl.2010.0827
Hypertrophy/Goiter
Presence of a ectopic tumor will excessively secrete thyroid stimulating hormone (TSH). Excessive TSH leads to excessive stimulation of the thyroid gland, thus increased synthesis and release of T3 and T4. Physiological effects include increased basal metabolic rate, weight loss, increased appetite, sweating, tremors, heat sensitivity, irritability, diarrhea, and insomnia (Pirahanchi et al., 2020)
Pirahanchi Y, Toro F, Jialal I. Physiology, Thyroid Stimulating Hormone. [Updated 2020 Jun 28]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2020 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK499850/
