Thyroid Gland Physiology MCQs
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- 1. Question
What is the embryological origin of the thyroid gland?CorrectIncorrect
It originates from an outgrowth during the fourth week of pregnancy.
- 2. Question
Which part of the thyroglossal duct is normally lost during development?CorrectIncorrect
The part that is lost can be identified as the foramen caecum.
- 3. Question
What is the main characteristic structure of thyroid tissue?CorrectIncorrect
These structures consist of single-cell layers of follicular cells surrounding a central region filled with colloid.
- 4. Question
What is the primary function of parafollicular cells in the thyroid gland?CorrectIncorrect
These cells produce a hormone involved in blood calcium regulation.
- 5. Question
Which type of innervation of the thyroid gland is most prominent?CorrectIncorrect
This type of innervation comes mainly from the superior cervical ganglion.
- 6. Question
What is the main blood supply to the upper parts of each thyroid lobe?CorrectIncorrect
These arteries branch off the external carotid arteries.
- 7. Question
In which vein does the blood from the inferior thyroid vein drain?CorrectIncorrect
This vein also receives blood from the left subclavian vein and left internal jugular vein.
- 8. Question
What type of cells are found in the thyroid gland that produce iodothyronines?CorrectIncorrect
These cells are also occasionally called thyrocytes.
- 9. Question
How does the activity of thyroid follicles affect the appearance of follicular cells?CorrectIncorrect
The appearance of these cells changes depending on their degree of stimulation.
- 10. Question
What are the two main physiologically active thyroid hormones?CorrectIncorrect
These hormones are iodinated molecules.
- 11. Question
How does iodide enter the follicular cells against an electrochemical gradient?CorrectIncorrect
This symporter transports two sodium and one iodide ions into the cell.
- 12. Question
Which hormone stimulates the synthesis of thyroglobulin and controls the sodium–iodide symporter?CorrectIncorrect
This hormone is produced by the anterior pituitary gland.
- 13. Question
Which transporter is involved in transporting iodide out of the follicular cell at the apical membrane and into the follicular lumen?CorrectIncorrect
This transporter's process is also stimulated by thyrotrophin.
- 14. Question
What is the function of thyroglobulin in thyroid hormone synthesis?CorrectIncorrect
- 15. Question
Which enzyme provides the energy necessary to drive the sodium–iodide symporter (NIS)?CorrectIncorrect
This enzyme pumps three sodium ions out of the cell in exchange for two potassium ions.
- 16. Question
Which membrane glycoprotein is found on the basolateral membranes of salivary glands, gastric mucosa, and mammary glands during lactation, allowing them to take up iodide?CorrectIncorrect
This glycoprotein is also found in thyroid follicular cells.
- 17. Question
What is the role of deiodinases in the synthesis and function of iodothyronines?CorrectIncorrect
Deiodinases are involved in the conversion of thyroid hormones in peripheral cells.
- 18. Question
What is the primary function of the parafollicular cells found interspersed between the follicles in the thyroid gland?CorrectIncorrect
These cells operate independently of the main thyroidal tissue.
- 19. Question
A 30-year-old woman presents with fatigue and weight gain during pregnancy. Laboratory tests reveal an increase in total thyroid hormone levels. What is the primary cause of this increase in circulating iodothyronine concentrations during pregnancy?CorrectIncorrect
The change in circulating hormone levels is related to a pregnancy-induced increase in a specific plasma protein.
- 20. Question
A patient is found to have elevated levels of reverse T3 (rT3). Which deiodinase is responsible for the conversion of T4 to rT3?CorrectIncorrect
This deiodinase removes the iodine atom at the 5' position of T4.
- 21. Question
Which enzyme is responsible for oxidizing inorganic iodide to reactive iodine in the apical membrane–colloid border?CorrectIncorrect
This enzyme is involved in the iodination and organification reactions.
- 22. Question
In the thyroid follicle, what is the main reservoir of iodothyronines?CorrectIncorrect
This substance is located in the follicle
- 23. Question
Which transporter mechanism is responsible for secreting T3 and T4 through the basolateral membranes of follicular cells into the general circulation?CorrectIncorrect
This transporter is located on the basolateral membrane of follicular cells.
- 24. Question
Which thyroid hormone has a shorter biological half-life?CorrectIncorrect
Compare the half-life of the more potent thyroid hormone with the less potent one.
- 25. Question
What is the result of linkage between two tyrosyls in the coupling reaction in the thyroid follicle?CorrectIncorrect
This product is formed by linking specific di-iodotyrosyls with mono- or di-iodotyrosyls.
- 26. Question
What type of thyroid hormone is primarily stored in the thyroid gland's follicular colloid?CorrectIncorrect
This hormone is stored in larger quantities than the more potent thyroid hormone.
- 27. Question
Which specific transporters are involved in the transport of free, unbound iodothyronines across peripheral cell membranes?CorrectIncorrect
These transporters are responsible for the movement of iodothyronines into their target cells.
- 28. Question
Which TR is restricted to the hypothalamus and pituitary and is associated with the negative feedback actions of the iodothyronines?CorrectIncorrect
This specific TR is involved in the feedback mechanism of thyroid hormones.
- 29. Question
Which enzyme primarily converts T4 to the more active T3 molecule within target cells?CorrectIncorrect
This enzyme plays a crucial role in the intracellular activation of thyroid hormones.
- 30. Question
What is the suggested action of iodothyronines on mitochondrial metabolism once they are bound to high-affinity binding sites in mitochondrial membranes?CorrectIncorrect
This action is related to energy production and heat synthesis in the mitochondria.
- 31. Question
What type of action can account for the effects of iodothyronines that have a much shorter latency than those normally associated with T3 and T4?CorrectIncorrect
These actions do not involve the activation or inhibition of specific gene transcription processes.
- 32. Question
What is the main action of deiodinase D3 in peripheral tissues?CorrectIncorrect
This enzyme is involved in the inactivation of thyroid hormones.
- 33. Question
What is the primary role of iodothyronines in the regulation of basal metabolic rate?CorrectIncorrect
This action involves the utilization of energy in the form of ATP.
- 34. Question
What are the two other potential mechanisms of action for iodothyronines, in addition to the nuclear genomic mechanism?CorrectIncorrect
These actions involve either mitochondrial DNA or direct effects on mitochondrial metabolism.
- 35. Question
What is the primary effect of T3 on energy provision in the cell?CorrectIncorrect
T3 plays a crucial role in regulating the metabolism and energy utilization within cells.
- 36. Question
Which type of receptors do iodothyronines bind to after crossing the nuclear membrane in target cells?CorrectIncorrect
These receptors are also known as thyroid hormone receptors.
- 37. Question
Which receptor has a far greater affinity for T3 than for T4?CorrectIncorrect
These receptors are involved in the cellular response to thyroid hormones.
- 38. Question
Which process is influenced by iodothyronines when they act on mitochondrial DNA?CorrectIncorrect
This action occurs when iodothyronines bind to high-affinity binding sites in mitochondrial membranes.
- 39. Question
A 30-year-old woman presents with increased sensitivity to cold, a decrease in her body temperature, and weight gain. What could be the possible underlying cause of her symptoms?CorrectIncorrect
Hypothyroidism is characterized by decreased heat production and the patient feels the cold.
- 40. Question
A 45-year-old man presents with weight loss, muscle weakness, and intolerance to heat. What condition could be causing these symptoms?CorrectIncorrect
Hyperthyroidism is associated with increased heat production, and the patient becomes heat intolerant.
- 41. Question
In a child with hyperthyroidism, what effect does the condition have on their linear growth and bone development?CorrectIncorrect
T3 affects specific TRs in bone end-plate chondrocytes, bone marrow stromal cells, and osteoblasts, resulting in overall stimulation of bone synthesis.
- 42. Question
A patient with hyperthyroidism exhibits symptoms of moderate hyperglycemia. What is the likely cause of this condition?CorrectIncorrect
The balance between glycogenesis and glycogenolysis depends on the overall thyroid hormone level in the circulation.
- 43. Question
Which of the following effects can hyperthyroidism have on children's growth and bone development?CorrectIncorrect
Hyperthyroidism affects bone age and growth in children.
- 44. Question
Which hormones primarily control thyroid iodothyronine synthesis, storage, and release?CorrectIncorrect
These hormones come from the anterior pituitary and hypothalamus.
- 45. Question
How do high concentrations of glucocorticoids affect biologically active thyroid hormone levels?CorrectIncorrect
Glucocorticoids affect the conversion of T4 to T3 in target tissues.
- 46. Question
What is the main cause of primary hypothyroidism?CorrectIncorrect
Primary hypothyroidism is often due to the body attacking its own thyroid gland.