Section 3

Question 1

What is the thyroid gland? Describe its location and function.

Answer 1

-in the neck
-anterior to the trachea and inferior to the larynx
-important structure in maintaining metabolic homeostasis

Question 2

What are the lobes of the thyroid gland?

Answer 2

-right lobe
-left lobe
-isthmus (sits between and connects the two lobes)

Question 3

What is the histology of the thyroid gland?

Answer 3

-composed of many structures called follicles
-each follicle is lined with simple cuboidal follicular cells that surround a central lumen filled with material called colloid
-dispersed between the follicles are the parafollicular or ‘C’ cells

*think of the gland being a bag of tennis balls, where the gland is the bag, and follicles are the tennis balls

Question 4

What is colloid?

Answer 4

a protein rich fluid secreted by the follicular cells of the thyroid gland

Question 5

what do each of the cells of the thyroid gland secrete?

Answer 5

specific hormones

Question 6

What are follicular cells?

Answer 6

-one of the cells of the thyroid gland
-simple cuboidal cells surrounding each follicle
-cells produce two hormones: T3 and T4
-T3: triiodothyronine
-T4: thyroxine
-they both act to increase the rate of metabolism and oxygen consumption

Question 7

What are C cells?

Answer 7

-one of the cells of the thyroid gland
-important in calcium homeostasis
-produce calcitonin: which is a hormone which lowers the blood calcium concentration

Question 8

Which pituitary gland hormone, when present in excess, results in higher levels of T3 and T4 which causing goitre?

Answer 8

TSH

Question 9

What is goitre?

Answer 9

a physiological condition where the thyroid gland expands in size, causing a large lump in the neck. This can be caused by an excess or a lack of thyroid hormones T3 and T4