thyroid gland

Question 1

what does thyroid gland tissue secrete

Answer 1

thyroxine (T4)
Tri-iodothronine (T3)
calcitonin

Question 2

what arteries supply the thyroid with blood

Answer 2

superior and inferior thyroid arteries

Question 3

which veins drain the arteries

Answer 3

superior and middle thyroid vein

inferior thyroid vein

Question 4

what is the negative feedback loop in the thyroid gland

Answer 4

when T4 and T3 are released into peripheral tissues, they can loop back to the pituitary gland and the hypothalamus to switch the loop off

Question 5

what are the 6 steps of thyroid hormone synthesis

Answer 5

• thyroglobulin synthesis
• uptake and concentration of iodide
• oxidation of iodide to iodine
• iodination of thyroglobulin
• formation of MIT and DIT
• secretion

Question 6

what do you get when there’s and MIT and DIT coupled together

Answer 6

triiodothyronine

Question 7

what do you get when there’s two DIT’s coupled together

Answer 7

thyroxine

Question 8

where is triiodothyronine and thyroxine stored until requires

Answer 8

in colloid thyroglobulin

Question 9

what is T4 converted to and what by?

Answer 9

converted to T3 by liver and kidney

Question 10

which is the major biologically active thyroid hormone

Answer 10

T3

Question 11

how is thyroid hormone transported

Answer 11

bound to serum proteins

Question 12

what hormones are available to tissues

Answer 12

free/unbound ones

Question 13

what are T3 and T4 bound by

Answer 13

plasma proteins

Question 14

effects of thyroid hormone

Answer 14

• increased metabolic rate
• increased glucose uptake
• increased glycogenolysis and gluconeogensis
• decreased glycogenesis
• increased lipolysis
• decreased lipogenesis
• increased breathing rate
• increased HR and force of contraction

Question 15

what does thyroid hormones do to basal metabolic rate

Answer 15

increases it

Question 16

how do thyroid hormones increase basal rate

Answer 16

• increase number and size of mitochondria
• increase oxygen use and rates of ATP hydrolysis
• increase synthesis of resp chain enzymes

Question 17

what do thyroid hormones do to thermogenesis

Answer 17

increase it

Question 18

what do thyroid hormones do to carbohydrate metabolism

Answer 18

• increase blood glucose

- increase insulin dependent glucose uptake into cells

Question 19

thyroid hormone effects on lipid metabolism

Answer 19

• mobilise fats from adipose tissue

- increase fatty acid oxidation in tissues

Question 20

thyroid hormone effect on protein synthesis

Answer 20

increase it

Question 21

how do thyroid hormones have an effect on growth

Answer 21

• growth hormone releasing hormone production and secretion requires thyroid hormones
• glucocorticoid-induced GHRH release is dependent on thyroid hormones

Question 22

hypothyroidism affect on CNS

Answer 22

slow intellectual functions

Question 23

hyperthyroidism affects on CNS

Answer 23

• nervousness
• hyperkinesis
• emotional lability

Question 24

what is thyroid hormones permissive sympathomimetic action

Answer 24

thyroid hormones increase responsiveness to adrenaline and sympathetic NS neurotransmitter, noradrenaline by increasing number of receptors

Question 25

where is D1 found

Answer 25

liver and kidney

Question 26

where is D2

Answer 26

heart and skeletal, CNS, fat, thyroid and pituitary

Question 27

where is D3

Answer 27

fetal tissue and placenta and brain