Section 39.4.1 (Exam 4) Hormones

Question 1

What are the 2 hormones the thyroid gland secretes?

Answer 1

Thyroxine and Calcitonin

Question 2

Where is thyroxine produced and what is its role?

Answer 2

It is produced in follicle epithelial cells and regulates metabolism

Question 3

Where is calcitonin produced and what is its role?

Answer 3

It is produced in cells between the follicles and regulates blood calcium levels

Question 4

What is thyroglobulin?

Answer 4

a polymer of tyrosine

Question 5

Where is thyroglobulin produced and secreted?

Answer 5

Produced in epithelial cells of the follicle and secreted into the lumen of the follicle

Question 6

What happens to thyroglobulin in the lumen of the follicle?

Answer 6

It is iodinated and stored until processed by the epithelial cells where it generates T_3 and T_4.

Question 7

Both T_3 and T_4 are generated by thyroglobulin. Describe which is more active and which is released more.

Answer 7

T_4 is release more and T_3 is a more active form.

Question 8

What is the function of deiodinases?

Answer 8

Convert T_4 to T_3

Question 9

What does the anterior pituitary secrete to produce thyroxine?

Answer 9

thyrotropin or thyroid-stimulating hormone (TSH), which activates the follicles to produce thyroxine

Question 10

Which side of the pituitary gland secretes TSH?

Answer 10

anterior pituitary

Question 11

What is the function of thyrotropin releasing hormone (TRH)?

Answer 11

Activates the TSH-producing pituitary cells

Question 12

How does thyroxine act based on its solubility?

Answer 12

Thyroxine is lipid-soluble

It binds to receptors in the nucleus to stimulate genes involved in metabolic pathways to increase metabolic rates

Question 13

What is the impact of insufficient thyroxine on a growing fetus or child?

Answer 13

can retard physical and mental development, resulting in a condition known as cretinism

Question 14

What is goiter?

Answer 14

An enlarged thyroid gland associated with hyperthyroidism (excess thyroxine) and hypothyroidism (lack of thyroxine)

Question 15

What is the most common cause of hyperthyroid goiter?

Answer 15

Graves’ disease – an autoimmune disease

Question 16

Describe what occurs in an individual with Graves’ disease and some of the symptoms they experience.

Answer 16

Body produces antibodies to bind to TSH receptors on follicle cells, continuously activating the thyroid gland to produce thyroxine – leading to uncontrolled production of thyroxine.

Symptoms – high metabolic rate, usually feel hot, buildup of fat behind eyeballs (causing them to bulge)

Question 17

What is the most common cause of hypothyroid goiter?

Answer 17

Iodine deficiency because without iodine the follicle cells are unable to produce thyroxine

Question 18

How does iodine deficiency cause hypothyroid goiter? What are some symptoms of hypothyroid goiter?

Answer 18

Follicle cells are unable to produce thyroxine.

Without thyroxine, thyrotropin (TSH) levels remain high, and the thyroid makes excess amounts thyroglobulin.

Symptoms – low metabolism, intolerance to cold, general physical and mental sluggishness