Histology of the Thyroid Gland

Question 1

Thyroid

Answer 1

Shaped like an H
Consists of two lobes connected by an isthmus extending over the second and third cartilaginous rings of trachea in the neck
Only gland to store the hormone products untill needed
30 million indv follicles in the human thyroid gland

Question 2

Connective tissue septa

Answer 2

Divides the tissue into discrete lobules

Question 3

Follicular cells

Answer 3

Hormon producing cells that make up the lobules
Secrete throglobulin into the colloid, where it is stored until thyroid stimulating hormone from the pituitary prompts release of thyroid hormones into the bloodstream

Question 4

Colloid

Answer 4

Fluid like substance, that follicular cells enclose

Question 5

Monoiodothyronine and Diiodothronine

Answer 5

Contain one and two iodine mokescules and are physiologically inactive

Question 6

Triodothronine and Tetraiodothronine

Answer 6

Three or four iodine molecules, are secreted into the blood stream to exter their stimulatory actions on the metabolic rate

Question 7

Size of follicle cells

Answer 7

Directly relatd to their metabolic activity and rate of hormone of secretion

Question 8

Active follicles

Answer 8

Columnar follicular cells, with reduced volume of stored colloid material

Question 9

Less active (resting) follicles

Answer 9

Cuboidal to squamous follicular cells, surround an abundance of stored colloid

Question 10

Follicle cells

Answer 10

Surrounded by delicate reticular network that includes an extensive capillary bed and lymphatic plexu

Question 11

Parafollicular cells

Answer 11

small group of pales cells
responsible for the release of calcitonin into the bloodstream
Secreted in response to abnormally high blood calcium lvls and acts to increase excretion of excess calcium in the urine

Question 12

Parathyoid hormone

Answer 12

opposes this action, serving to raise blood calcium lvls by stimulating the release of calcium from the bones and inhibiting excretion of calcium in the urine