IBSS Exam 1540 Exam 1 Part 2
2025/2026 Exam Questions and Verified
Answers | Already Graded A+
What are two aspects about the thyroid gland's anatomy that hint to you
that it is a very important organ? - 🧠ANSWER ✔✔-the gland is well
vascularized
-it is one of the largest endocrine glands
What makes up the colloid found within the follicles of the thyroid gland? -
🧠ANSWER ✔✔thyroglobulin
What is the function of the parafollicular cells in the thyroid? - 🧠ANSWER
✔✔they make calcitonin
,What two dietary components are required in order to synthesize thyroid
hormone? - 🧠ANSWER ✔✔tyrosine and iodine
What is the role of NIS in the synthesis of thyroid hormone? - 🧠ANSWER
✔✔it is a sodium iodide symptorter that binds both molecules in order to
bring them into thyroid cells
What is the role of TSH in regads to NIS in the synthesis of thyroid
hormone? - 🧠ANSWER ✔✔TSH activates the NIS symptorter, there by
helping import iodine into thyroid cells to synthesize hormone with
What happens to iodide once it enters the thyroid cells? - 🧠ANSWER ✔✔it
migrates towards the colloid and enters through a transporter
What reaction is catalyzed by thyroid peroxidase in the synthesis of thyroid
hormone? - 🧠ANSWER ✔✔it converts 2 I-, hydrogen peroxide, and two
protons into iodine and 2 molecules of water
Why is iodine so important in the synthesis of thyroid hormone? -
🧠ANSWER ✔✔it reacts with tyrosine residues found on the thyroglobulin in
the thyroid follicle's colloid
Which enzyme in the synthesis of thyroid hormone oxidizes iodide and
adds iodine to tyrosine? - 🧠ANSWER ✔✔thyroid peroxidase
,What is the role of TSH in the synthesis of thyroid hormone? - 🧠ANSWER
✔✔it stimulates thyroid peroxidase, an enzyme involved in synthesizing
iodine and adding it to tyrosine on thyroglobulin. It also causes megalin to
endocytose the thyroid hormone precursor into the thyroid cells
What component of the thyroid gland synthesizes thyroglobulin? -
🧠ANSWER ✔✔the thyroid cells
What is the difference between T3 and T4 in terms of their synthesis? -
🧠ANSWER ✔✔T3 is formed when a Di-iodo-thyrlobgulin is combined with
MIT
T4 is formed when two DITs combine
Which is the essential enzyme in the synthesis of thyroid hormone? -
🧠ANSWER ✔✔thyroid peroxidase
Which enzyme converts T4 to T3 in thyroid hormone synthesis? -
🧠ANSWER ✔✔5'deiodinase
Why might it be helpful for 5'-deiodinase to convert T4 to T3 in peripheral
tissues? - 🧠ANSWER ✔✔because T3 is a more powerful form of thyroid
hormone than T4 is
3
COPYRIGHT©JOSHCLAY 2025/2026. YEAR PUBLISHED 2025. COMPANY REGISTRATION NUMBER: 619652435. TERMS OF USE. PRIVACY
STATEMENT. ALL RIGHTS RESERVED
, How is T4 converted to T3? - 🧠ANSWER ✔✔5' deiodinase removes an
iodine from it
What happens if T4 reacts with 5-deidoniase instead of 5' deiodinase? -
🧠ANSWER ✔✔it forms a metabolically inactive reverse T3
Which form of thyroid hormone can only be formed in the thyroid, not
peripherally? - 🧠ANSWER ✔✔T4
Which thyroid hormone can be formed in the thyroid, but is mostly formed
peripherally? - 🧠ANSWER ✔✔T3
Between T3 and T4, which thyroid hormone is more potent? - 🧠ANSWER
✔✔T3
What are four conditions that inhibit 5' deiodinase and slow the peripheral
rate of conversion of T4 to T3? - 🧠ANSWER ✔✔fasting, severe illness, high
glucocorticoid levels, drugs, and in a fetus
What is the effect of an iodine deficiency on thyroid hormone? - 🧠ANSWER
✔✔there will be decreased synthesis of thyroid hormones, which increases
TSH secretion via negative feedback. MIT is produced more than DIT due
2025/2026 Exam Questions and Verified
Answers | Already Graded A+
What are two aspects about the thyroid gland's anatomy that hint to you
that it is a very important organ? - 🧠ANSWER ✔✔-the gland is well
vascularized
-it is one of the largest endocrine glands
What makes up the colloid found within the follicles of the thyroid gland? -
🧠ANSWER ✔✔thyroglobulin
What is the function of the parafollicular cells in the thyroid? - 🧠ANSWER
✔✔they make calcitonin
,What two dietary components are required in order to synthesize thyroid
hormone? - 🧠ANSWER ✔✔tyrosine and iodine
What is the role of NIS in the synthesis of thyroid hormone? - 🧠ANSWER
✔✔it is a sodium iodide symptorter that binds both molecules in order to
bring them into thyroid cells
What is the role of TSH in regads to NIS in the synthesis of thyroid
hormone? - 🧠ANSWER ✔✔TSH activates the NIS symptorter, there by
helping import iodine into thyroid cells to synthesize hormone with
What happens to iodide once it enters the thyroid cells? - 🧠ANSWER ✔✔it
migrates towards the colloid and enters through a transporter
What reaction is catalyzed by thyroid peroxidase in the synthesis of thyroid
hormone? - 🧠ANSWER ✔✔it converts 2 I-, hydrogen peroxide, and two
protons into iodine and 2 molecules of water
Why is iodine so important in the synthesis of thyroid hormone? -
🧠ANSWER ✔✔it reacts with tyrosine residues found on the thyroglobulin in
the thyroid follicle's colloid
Which enzyme in the synthesis of thyroid hormone oxidizes iodide and
adds iodine to tyrosine? - 🧠ANSWER ✔✔thyroid peroxidase
,What is the role of TSH in the synthesis of thyroid hormone? - 🧠ANSWER
✔✔it stimulates thyroid peroxidase, an enzyme involved in synthesizing
iodine and adding it to tyrosine on thyroglobulin. It also causes megalin to
endocytose the thyroid hormone precursor into the thyroid cells
What component of the thyroid gland synthesizes thyroglobulin? -
🧠ANSWER ✔✔the thyroid cells
What is the difference between T3 and T4 in terms of their synthesis? -
🧠ANSWER ✔✔T3 is formed when a Di-iodo-thyrlobgulin is combined with
MIT
T4 is formed when two DITs combine
Which is the essential enzyme in the synthesis of thyroid hormone? -
🧠ANSWER ✔✔thyroid peroxidase
Which enzyme converts T4 to T3 in thyroid hormone synthesis? -
🧠ANSWER ✔✔5'deiodinase
Why might it be helpful for 5'-deiodinase to convert T4 to T3 in peripheral
tissues? - 🧠ANSWER ✔✔because T3 is a more powerful form of thyroid
hormone than T4 is
3
COPYRIGHT©JOSHCLAY 2025/2026. YEAR PUBLISHED 2025. COMPANY REGISTRATION NUMBER: 619652435. TERMS OF USE. PRIVACY
STATEMENT. ALL RIGHTS RESERVED
, How is T4 converted to T3? - 🧠ANSWER ✔✔5' deiodinase removes an
iodine from it
What happens if T4 reacts with 5-deidoniase instead of 5' deiodinase? -
🧠ANSWER ✔✔it forms a metabolically inactive reverse T3
Which form of thyroid hormone can only be formed in the thyroid, not
peripherally? - 🧠ANSWER ✔✔T4
Which thyroid hormone can be formed in the thyroid, but is mostly formed
peripherally? - 🧠ANSWER ✔✔T3
Between T3 and T4, which thyroid hormone is more potent? - 🧠ANSWER
✔✔T3
What are four conditions that inhibit 5' deiodinase and slow the peripheral
rate of conversion of T4 to T3? - 🧠ANSWER ✔✔fasting, severe illness, high
glucocorticoid levels, drugs, and in a fetus
What is the effect of an iodine deficiency on thyroid hormone? - 🧠ANSWER
✔✔there will be decreased synthesis of thyroid hormones, which increases
TSH secretion via negative feedback. MIT is produced more than DIT due
