Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
34 Cards in this Set
- Front
- Back
|
in the thyroid gland how are the cells arranged
|
cells form a ring (follicle)
|
|
|
tell me the first 2 steps in thyroid hormone synth
|
1. active transport of Iodine w/ Na into cell
2. iodone goes to lumen and thyroid peroxidase on membrane converts I- to I+ or IO- using peroxide |
|
|
overall goal of thyroid hormones
|
either (1) prevent excessive TH production or (2) supplement poor TH production
hypo or hyper |
|
|
TH build from ___ called ___
|
from tyrosine called thyronine
|
|
|
T4
|
I on 3,5, and the 3 and 5 primes
look at structure |
|
|
T3
|
remove 5 prime I group
|
|
|
if you remove 5 Iodine
|
reverse T3
|
|
|
reverse T3
|
inactive metabolite
|
|
|
compare amount and potentcy of T3 and T4
|
T3 ~4x more potent
T4 about 4x more in amount (80% T4) |
|
|
what is this?
|
t4
|
|
what is this?
|
t4
|
|
|
after I- gets converted to I+ or IO- via TPO and transported into lumen what happens?
|
the TPO adds hypoiodine to the thyroglobulin
|
|
|
where are thyroglobulin (Tg) molecules located?
|
in the lumen of the follicle
|
|
|
tell me about Tg (thyroglobulin)
|
v.v large molecule that can have ONE or TWO iodinated tyrosines...when 2+2 combine you get T4, when 1+2 combine you get T3
|
|
|
more T4 or T3?
|
4x more T4
|
|
|
how is T4/T3 released?
|
Tg renenters cells in lysosome and is broken down by proteases, freeing T3 and T4....which leaves and goes into circulation
|
|
|
iodine deficiency get a goiter. why?
|
when you have low TH the ant pit tries to stimulate the thyroid gland via TSH causing the thyroid cells to ENLARGE
|
|
|
iodothyronine deiodinase
|
final step in periphery where T4 gets converted to T3 by removal of 5 prime iodo group
|
|
|
T3 more potent that T4
|
yes
|
|
|
thyroid hormone binding globulin
|
most TH is bound up by this protein...acts as a buffer
.03% free T4 and 0.3% free T3 |
|
|
actions of thyroid hormone are intiated by __
|
T3 mostly
|
|
|
hyperthyroidism aka ___
|
thyrotoxicosis also when severe called thyroid storm
|
|
|
Sx of hyperthyroidism
|
excessive adrenergic stimulation
incr HR and CO decreased peripheral resistance |
|
|
Tx of hyperthyroidism
|
131 Iodine....it slowly destroys thyroid cells
|
|
|
what % of population has subacute form of HYPOthyroidism
|
7%??
|
|
|
HYPOthyroidism Tx
|
replace hormones (synthetic T3/T4)
though T4 mostly given b/c it has a 7 day half life...more stable...and event gets converted to T3 |
|
|
synthetic T3 and T4 half lives
|
T3 = 1 day
T4 = 7 days |
|
|
2 drugs for hyperthyroidism and how do they work?
|
propylthiouracil
methimazole work by inhibiting thyroid peroxidase (TPO) |
|
|
propylthiouracil
|
Tx severe cases of hyperthyroidism (storm) b/c it works fast
also inhibits the deiodinase NOT take by preggies |
|
|
methimazole
|
PREFERRED tx for hyperthyroism; blocks TPO
|
|
|
what drugs might you include w/ methimazole?
|
beta blockers
g-corts (dexamethasome) --> supresses production of Ab (grave's disease.....) |
|
|
T or F you use PTU and not methimazole in preggies
|
true (my mistake elswhere)
|
|
|
problems w/ PTU
|
liver failure....0.1% ppl
|
|
|
agranulocytosis
|
toxicity of hyperthyroid drugs
loss of production of granulocytes, fever, sore throat |
