Thyroid Gland Introduction

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What is the molecular weight of thyroglobulin?

1320 kDa
990 kDa
660 kDa (correct)
330 kDa

What percentage of thyroglobulin is made up of carbohydrates by weight?

20%
10% (correct)
15%
5%

How many tyrosine residues are normally incorporated into thyroid hormones?

1-2
10-12
15-20
4-8 (correct)

What is the name of the enzyme that mediates the oxidation and reaction of iodide with thyroglobulin?

Thyroid peroxidase (B) Signup and view all the answers

What happens to the colloid when there is a need for thyroid hormone secretion?

It is internalized by the thyrocytes by endocytosis (B) Signup and view all the answers

What is the product formed when two DIT molecules undergo an oxidative condensation?

T4 (A) Signup and view all the answers

What is the approximate percentage of iodinated compounds in the normal human thyroid that is T3?

7% (D) Signup and view all the answers

What is the main difference between the two theories of thyroglobulin coupling?

One theory involves intramolecular coupling while the other involves intermolecular coupling. (A) Signup and view all the answers

What is the approximate amount of T4 secreted by the human thyroid per day?

80 μg (103 nmol) (A) Signup and view all the answers

What is the function of free thyroid hormones in plasma?

To inhibit pituitary secretion of TSH. (A) Signup and view all the answers

What is the name of the protein that binds to thyroid hormones in plasma and tissues?

All of the above (D) Signup and view all the answers

What is the approximate normal total plasma T4 level in adults?

8 μg/dL (103 nmol/L) (A) Signup and view all the answers

What is the primary function of thyroid hormones in the body?

To stimulate O2 consumption by most of the cells in the body (C) Signup and view all the answers

What is the consequence of thyroid gland dysfunction during fetal and neonatal life?

Mental retardation and dwarfism (B) Signup and view all the answers

What is the hormone that regulates circulating levels of calcium?

Calcitonin (A) Signup and view all the answers

What is the hormone that stimulates the thyroid gland to produce thyroid hormones?

Thyroid-stimulating hormone (TSH) (C) Signup and view all the answers

What is the consequence of hypothyroidism in adults?

Mental and physical slowing and poor resistance to cold (A) Signup and view all the answers

What is the negative feedback control mechanism that regulates thyroid hormone production?

High circulating levels of thyroid hormones acting on the hypothalamus and the anterior pituitary (A) Signup and view all the answers

Which protein has the largest capacity to bind T4?

Albumin (A) Signup and view all the answers

What percentage of circulating T4 is normally converted to T3 in adult humans?

45% (D) Signup and view all the answers

What is the half-life of transthyretin?

2 days (D) Signup and view all the answers

What is the role of deiodination reactions in the liver, kidneys, and other tissues?

To catabolize and provide a local supply of T3 (C) Signup and view all the answers

What is the primary mediator of the physiologic effects of thyroid secretion?

T3 (C) Signup and view all the answers

What inhibits TSH secretion in a negative feedback manner?

Circulating free T4 and T3 (A) Signup and view all the answers

What happens to iodide binding after the injection of TSH?

It increases within minutes (C) Signup and view all the answers

What is the effect of thyroid hormones on oxygen consumption?

It stimulates oxygen consumption (B) Signup and view all the answers

What is the result of prolonged TSH stimulation on the thyroid gland?

The gland becomes detectably enlarged (A) Signup and view all the answers

How do thyroid hormones regulate lipid metabolism?

By regulating lipid metabolism (C) Signup and view all the answers

What happens to the expression of genes when thyroid hormones bind to TR in the nuclei?

Gene expression is increased (B) Signup and view all the answers

What is the effect of thyroid hormones on the absorption of carbohydrates from the intestine?

They increase the absorption of carbohydrates (C) Signup and view all the answers

What is the approximate distribution of DIT in the normal human thyroid?

33% (C) Signup and view all the answers

Which of the following proteins has the smallest capacity to bind T4?

Albumin (B) Signup and view all the answers

What is the product formed when MIT condenses with DIT?

T3 (C) Signup and view all the answers

What is the primary mechanism by which TBG binds to T4?

High-affinity binding (C) Signup and view all the answers

What is the approximate amount of T3 secreted by the human thyroid per day?

4 μg (7 nmol) (A) Signup and view all the answers

What percentage of circulating T4 is converted to RT3?

45% (A) Signup and view all the answers

What is the primary function of free thyroid hormones in plasma?

To inhibit pituitary secretion of TSH (B) Signup and view all the answers

Which hormone inhibits TSH secretion in a negative feedback manner?

Free T4 and T3 (C) Signup and view all the answers

What is the result of the coupling of two DIT molecules?

Formation of T4 (B) Signup and view all the answers

What is the main purpose of deiodination reactions in the liver, kidneys, and other tissues?

To catabolize thyroid hormones and provide a local supply of T3 (C) Signup and view all the answers

What is the half-life of albumin?

13 days (A) Signup and view all the answers

What is the approximate weight percentage of carbohydrate in thyroglobulin?

10% (C) Signup and view all the answers

What is the percentage of circulating T3 that is secreted by the thyroid?

13% (D) Signup and view all the answers

How many tyrosine residues are normally incorporated into thyroid hormones?

4–8 (C) Signup and view all the answers

What is the function of thyroid peroxidase in thyroid hormone synthesis?

To generate reactive iodine species that can attack thyroglobulin (B) Signup and view all the answers

What happens to the colloid when there is a need for thyroid hormone secretion?

It is internalized by the thyrocytes and directed toward lysosomal degradation (A) Signup and view all the answers

What is the product formed when two DIT molecules undergo an oxidative condensation?

T4 (A) Signup and view all the answers

What is the molecular weight of thyroglobulin?

660 kDa (D) Signup and view all the answers

What is the primary function of thyroid hormones in maintaining optimal metabolism?

Influencing mentation and body mass (D) Signup and view all the answers

What is the consequence of thyroid gland dysfunction during fetal and neonatal life?

Mental retardation and dwarfism (D) Signup and view all the answers

What stimulates the thyroid gland to produce thyroid hormones?

Thyroid-stimulating hormone (TSH) (A) Signup and view all the answers

What is the effect of hypothyroidism in adults?

Mental slowing and physical slowing (A) Signup and view all the answers

What is the function of calcitonin?

Regulating circulating levels of calcium (C) Signup and view all the answers

What controls the secretion of thyroid-stimulating hormone (TSH)?

Thyroid hormones (C) Signup and view all the answers

What is the effect of TSH on thyroid function?

It increases iodide binding, synthesis of T3, T4, and iodotyrosines, and secretion of thyroglobulin into the colloid (A) Signup and view all the answers

What is the effect of thyroid hormones on lipid metabolism?

They increase lipid metabolism (C) Signup and view all the answers

What is the mechanism of action of thyroid hormones?

They enter cells and bind to receptors in the nuclei (B) Signup and view all the answers

What is the effect of thyroid hormones on oxygen consumption?

They increase oxygen consumption (A) Signup and view all the answers

What is the consequence of prolonged TSH stimulation on the thyroid gland?

The thyroid gland becomes detectably enlarged (A) Signup and view all the answers

What is the effect of thyroid hormones on the dissociation of oxygen from hemoglobin?

They increase the dissociation of oxygen from hemoglobin (B) Signup and view all the answers

Thyroid Gland Introduction

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Questions and Answers

What is the molecular weight of thyroglobulin?

What percentage of thyroglobulin is made up of carbohydrates by weight?

How many tyrosine residues are normally incorporated into thyroid hormones?

What is the name of the enzyme that mediates the oxidation and reaction of iodide with thyroglobulin?

What happens to the colloid when there is a need for thyroid hormone secretion?

What is the product formed when two DIT molecules undergo an oxidative condensation?

What is the approximate percentage of iodinated compounds in the normal human thyroid that is T3?

What is the main difference between the two theories of thyroglobulin coupling?

What is the approximate amount of T4 secreted by the human thyroid per day?

What is the function of free thyroid hormones in plasma?

What is the name of the protein that binds to thyroid hormones in plasma and tissues?

What is the approximate normal total plasma T4 level in adults?

What is the primary function of thyroid hormones in the body?

What is the consequence of thyroid gland dysfunction during fetal and neonatal life?

What is the hormone that regulates circulating levels of calcium?

What is the hormone that stimulates the thyroid gland to produce thyroid hormones?

What is the consequence of hypothyroidism in adults?

What is the negative feedback control mechanism that regulates thyroid hormone production?

Which protein has the largest capacity to bind T4?

What percentage of circulating T4 is normally converted to T3 in adult humans?

What is the half-life of transthyretin?

What is the role of deiodination reactions in the liver, kidneys, and other tissues?

What is the primary mediator of the physiologic effects of thyroid secretion?

What inhibits TSH secretion in a negative feedback manner?

What happens to iodide binding after the injection of TSH?

What is the effect of thyroid hormones on oxygen consumption?

What is the result of prolonged TSH stimulation on the thyroid gland?

How do thyroid hormones regulate lipid metabolism?

What happens to the expression of genes when thyroid hormones bind to TR in the nuclei?

What is the effect of thyroid hormones on the absorption of carbohydrates from the intestine?

What is the approximate distribution of DIT in the normal human thyroid?

Which of the following proteins has the smallest capacity to bind T4?

What is the product formed when MIT condenses with DIT?

What is the primary mechanism by which TBG binds to T4?

What is the approximate amount of T3 secreted by the human thyroid per day?

What percentage of circulating T4 is converted to RT3?

What is the primary function of free thyroid hormones in plasma?

Which hormone inhibits TSH secretion in a negative feedback manner?

What is the result of the coupling of two DIT molecules?

What is the main purpose of deiodination reactions in the liver, kidneys, and other tissues?

What is the half-life of albumin?

What is the approximate weight percentage of carbohydrate in thyroglobulin?

What is the percentage of circulating T3 that is secreted by the thyroid?

How many tyrosine residues are normally incorporated into thyroid hormones?

What is the function of thyroid peroxidase in thyroid hormone synthesis?

What happens to the colloid when there is a need for thyroid hormone secretion?

What is the product formed when two DIT molecules undergo an oxidative condensation?

What is the molecular weight of thyroglobulin?

What is the primary function of thyroid hormones in maintaining optimal metabolism?

What is the consequence of thyroid gland dysfunction during fetal and neonatal life?

What stimulates the thyroid gland to produce thyroid hormones?

What is the effect of hypothyroidism in adults?

What is the function of calcitonin?

What controls the secretion of thyroid-stimulating hormone (TSH)?

What is the effect of TSH on thyroid function?

What is the effect of thyroid hormones on lipid metabolism?

What is the mechanism of action of thyroid hormones?

What is the effect of thyroid hormones on oxygen consumption?

What is the consequence of prolonged TSH stimulation on the thyroid gland?

What is the effect of thyroid hormones on the dissociation of oxygen from hemoglobin?

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