30 Questions
What is the main storage of the thyroid hormones within the thyroid gland?
Colloid
Where are the thyroid glands located in most mammals?
Caudal to the trachea at the level of the first or second tracheal ring
Which of the following is NOT a function of the thyroid hormones?
Regulating body temperature
What is the half-life of thyroxine?
7-10 days
Which type of cells in the thyroid gland synthesize the thyroid hormones?
Follicular cells
Which of the following is NOT a type of amine hormone?
Insulin
Which of the following is NOT a physiological action of thyroid hormones?
Increase blood flow and cardiac output
What is the minimal rate of energy expenditure per unit time at rest called?
Basal metabolic rate
Which of the following is NOT a metabolic effect of thyroid hormones?
Increase cellular uptake and degradation of LDL
What is the main cause of hyperthyroidism in cats?
Tumors of the thyroid gland
What is the main symptom of hypothyroidism in dogs?
Lethargy and obesity
What is the primary cause of hypothyroidism in dogs?
Lymphocytic thyroiditis
What is the major substrate that combines with iodine to form thyroid hormones?
Tyrosine
Where does iodine come from in the thyroid hormone synthesis process?
It is converted from iodide in the intestinal tract
Which cells secrete calcitonin?
Parafollicular cells
How do thyroid follicle cells trap iodide?
Active transport process
What is the intracellular concentration of iodide compared to the extracellular concentration in the thyroid follicle cells?
Higher
What enzyme is responsible for the synthesis of thyroid hormones in the thyroid follicle lumen?
Thyroid peroxidase
Which of the following is the correct sequence of events in the production of thyroid hormones?
Organification, tyrosine iodination, coupling
What is the result of the fusion of two iodinated tyrosines?
T4 or Thyroxine
What is the major hormone produced by the follicular cells?
T4
Where are T3 and T4 stored before secretion?
In the colloid
How are thyroid hormones transported in the blood?
Attached to thyroxine-binding globulin (TBG) and albumin
What is the primary function of thyroid hormones?
Control of metabolism
Which gland typically enlarges due to iodine deficiency?
Thyroid gland
What are the compounds that interfere with iodine uptake by the thyroid gland or with normal synthesis of thyroid hormones called?
Goitrogens
Which tests can be used for the diagnosis of endocrine disorders?
All of the above
Which hormone suppression test is used to evaluate thyroid function?
T3 suppression test
Which of the following is NOT a factor that can lead to iodine deficiency?
Excessive iodine intake
What is the role of goitrogens in the development of goiter?
They inhibit iodine uptake by the thyroid gland
Test your knowledge on the process of organification and tyrosine iodination in the thyroid gland. Learn about the formation of monoiodotyrosine (MIT) and diiodotyrosine (DIT), as well as the coupling of iodinated tyrosines.
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