Regulatory effects of thyroid hormone

Question 1

what do follicular cells secrete?

Answer 1

thyroid hormone

Question 2

what hormones does the thyroid gland produce?

Answer 2

T3 and T4

Question 3

what is essential for the synthesis of T3 and T4

Answer 3

iodine

Question 4

what are sources of iodine?

Answer 4

seafish, shellfish, cereal, grains

Question 5

how many more times concentration is iodine in the follicular cells to plasma ?

Answer 5

20-50x

Question 6

what does the sodium iodine co transporter in the thyroid gland transport?

Answer 6

2 sodium for every iodine ion

Question 7

what does the sodium electrochemical gradient in thyroid provide?

Answer 7

energy for secondary active transport of iodine

Question 8

what is thyroglobulin?

Answer 8

glycoprotein synthesised by follicular cells and released into the colloid by exocytosis

Question 9

what happens to tyrosine residues on thyroglobulin?

Answer 9

they get iodinated by oxidised iodine giving monoiodotyrosine and diiodotyrosine

Question 10

what does thyroglobulin bound to T3 or T4 make up?

Answer 10

the colloid

Question 11

what happens when thyroglobulin is taken up into follicular cells?

Answer 11

the thyroid hormones are released

Question 12

how does synthesis of T3 and T4 occur?

Answer 12

hypothalamus releases thyrotropin- releasing hormone which acts on the anterior pituitary and releases thyroid stimulating hormone acting on the thyroid gland to produce the hormones

Question 13

how does negative feedback of T3 and T4 occur?

Answer 13

feedback to hypothalamus and the anterior pituitary to block release of TRH and TSH

Question 14

does T3 and T4 have good solubility?

Answer 14

No they have poor solubility in water

Question 15

what specific proteins are the thyroid hormones associated with in blood?

Answer 15

• thyroid hormone binding globulin
• transthyretin
• albumin

Question 16

how much more T4 is secreted than T3

Answer 16

x10more

Question 17

what thyroid hormone is more active,

Answer 17

T3

Question 18

what can monodeionisation in target cells convert?

Answer 18

T4 to T3

Question 19

how does deionise enzyme 3 regulate activity of thyroid hormone?

Answer 19

produces reverse T3 from T4 to protect cells from action of the thyroid hormones

Question 20

how do D1 and D2 enzymes regulate activity of thyroid hormone

Answer 20

converts T4 to active T3

Question 21

what is required to transport thyroid hormones across the plasma membrane?

Answer 21

transporter proteins

Question 22

what does the thyroid hormone act on in the nucleus?

Answer 22

nuclear thyroid receptors, a hormone-sensitive transcription factor

Question 23

what are the metabolic effect of thyroid hormones?

Answer 23

• increased BMR
• increased oxygen consumption
• increased thermogenesis

Question 24

how does the thyroid hormone effect cardiovascular?

Answer 24

• increased CO
• increased HR and SV

Question 25

what are the neurological effects of thyroid hormones?

Answer 25

- enhances wakefulness - enhances memory - enhances alertness - enhances reflexes

Question 26

how are thyroid hormones essential for growth and development?

Answer 26

- essential for foetal neural and bone development - essential for normal bone growth after birth - essential for normal tooth development

Question 27

what is hyperthyroidism?

Answer 27

promotes a hyper-metabolic state characterised by increased resting energy expenditure and weight loss, high HR and BP

Question 28

what is hypothyroidism?

Answer 28

reduced resting energy expenditure and weight gain, lethargy and weakness

Question 29

what is the treatment for hypothyroidism?

Answer 29

levothyroxine

Question 30

what is the primary source of energy expenditure in humans?

Answer 30

basal metabolic rate