Physical Sciences 21

Question 1

how much iodine is required by body?

Answer 1

50 mg

we are good at recycling iodide

Question 2

where do we absorb it from?

Answer 2

absorbed from gut track in same manner as chlorides

Question 3

sodium iodide symporter

Answer 3

on basal membrane of thyroid cell (faces outward)

carries sodium and iodide INTO cells

energy via Na/K ATPase (2-transport)

Question 4

Pendrin

Answer 4

Chloride-iodide counter-transporter

apical end of cell

pumps iodide into the follicle

Question 5

peroxidase

Answer 5

converts iodide into iodine

Question 6

organification of iodide

Answer 6

combining iodine with tyrosine on thyroglobulin

catalyzed by peroxidase

Question 7

result of organification

Answer 7

monoiodotyrosine (MIT) (1 iodine) and diodetyrosine (DIT) (2 iodine)

Question 8

T4

Answer 8

thyroxine

DIT + DIT

formed more than T3

Question 9

what synthesizes thyroglobulin

Answer 9

thyroid cells

inserted in thyroid follicle so that it can bind to thyroglobulin

Question 10

how many iodine can we bind with a tyrosine molecule?

Answer 10

4

Question 11

T3

Answer 11

DIT + MIT

more active form

Question 12

where is thyroglobulin stored

Answer 12

stored in colloid with MIT, DIT, T3, T4 attached until needed

Question 13

thryoglobulin

Answer 13

secreted by thyroid cells

70 tyrosine AA that bind iodine (I2 o I3)

Question 14

hyperthyroidism is caused by

Answer 14

grave’s disease

adenoma

Question 15

symptoms of hyperthyroidism

Answer 15

high excitability 
intolerance to heat 
increased sweating 
mild to extreme weight loss 
varying decrees of diarrhea 
muscle weakness