thyroid

Question 1

what is the body’s largest wholly endocrine gland?

Answer 1

thyroid gland

Question 2

what is the most important function of the thyroid gland?

Answer 2

basal metabolism regulation

Question 3

is the thyroid gland normally palpable?

Answer 3

no!

Question 4

what is the term for palpable enlargement of the thyroid?

Answer 4

goiter

Question 5

what cells contain iodide?

Answer 5

follicular cells of the thyroid

Question 6

what cells secrete calcitonin?

Answer 6

parafollicular cells

Question 7

what cells synthesize and secrete thyroglobulin?

Answer 7

follicular cells

Question 8

what cells secrete T3 and T4?

Answer 8

follicular cells

Question 9

what is the role of calcitonin?

Answer 9

ca++ and phosphorus metabolism

• decrease blood [ca++]
• increase urinary loss of ca++

Question 10

what is the thyroid’s blood supply like?

Answer 10

it has the greatest blood flow per gram of tissue in the body

Question 11

regulation of the thyroid gland is _____ dependent.

Answer 11

pituitary dependent

Question 12

hormone regulation for the thyroid:

Answer 12

TRH (hypothalamus) -> TSH (pituitary) -> T3,T4 (thyroid)

Question 13

what do vacuoles in the colloid indicate>

Answer 13

that the follicle is active

Question 14

what is needed for the synthesis of thyroid hormone?

Answer 14

iodine

Question 15

what are the 3 steps to liberation of T3 + T4??

Answer 15

• endocytosis by thyroid epithelial cells (colloid contains thyroglobulin)
• lysosomes fuse with endocytotic vesicles (lytic enzymes free thyroid hormones)
• free thyroid hormones diffuse from lysosomes, out of cell and into blood

Question 16

how to thyroid hormones travel through the blood to target cells?

Answer 16

carrier proteins

Question 17

which thyroid hormone is a prohormone?

Answer 17

T4 ->T3

Question 18

is there more T3 or T4 in the blood?

Answer 18

there is 20X more T4 than T3 in the blood

Question 19

T3/T4 breadown are de-iodinated and decarboxylated to become what?

Answer 19

thyronine

Question 20

what is the parafollicular hormone?

Answer 20

calcitonin

Question 21

what type of hormone is calcitonin?

Answer 21

poly-peptide hormone

Question 22

what are the actions of calcitonin on osteoclasts and the kidneys?

Answer 22

• osteoclasts: blocks osteoclasts action (inhibits bone resorption)
• kidneys: blocks renal reabsorption of calcium and phosphorus

Question 23

what is calcitonin’s action on PTH?

Answer 23

antagonistic

Question 24

what causes goiter 90% of the time?

Answer 24

iodine deficiency

Question 25

goiter is a sign of?

Answer 25

hyperthyroidism

Question 26

what are other signs of hyperthyroidism?

Answer 26

- goiter - heat insensitivity - unkempt coat - eye sign - tachycardia - weight loss

Question 27

how can you test borderline hyperthyroid cases?

Answer 27

- differentiated by TSH stimulation test - tumors aren't stimulated by TSH - thyroid scan

Question 28

treatment for hyperthyroidism

Answer 28

- antithyroid drug - radioactive idodine - surgery

Question 29

what disease is a deficiency of thyroid follicular hormones?

Answer 29

hypothyroidism

Question 30

clinical signs for hypothyroidism

Answer 30

- elevated canine thyroglobulin auto-antibodies (detects autoimmune disease) - alopecia on tail - lethargy - cold intolerance - weight gain - hyperpigmentation of skin

Question 31

what is the treatment for hypothyroidism?

Answer 31

synthetic T4