Thyroid 1 Flashcards
Thyroid hormones SYNTHESIS
-dependent on iodine
T/F
T
Thyroid hormones SYNTHESIS
DEPENDENT ON TYROSINE
T/F
T
THYROGLOBULIN is synthesized _____cellularly at ___ surface OF follicular cells and stored in _____
extra
luminal
FOLLICULAR LUMEN
Effects of Iodine
-during iodine deficiency, the hormone synthesis is impaired
T/F
T
Effects of Iodine
excess iodine inhibits synthesis
T/F
T
Thyroid hormone secretions
-with ____ stimulation ,____ brings the _____ back into the ____ to be degraded into ___ and ____
TSH
endocytosis
thyroglobulin
follicular cells
T3 and T4
Thyroid hormone binding
- __% of thyroid hormone in the blood is bound
- it could be to thyroxine-____
- thyroxine- ______ (——-)
- _____
99
binding globulin
binding prealbumin; transthyretin
albumin
about ____ times as much as is secreted and degraded in a single day(buffer)
three
T4 binds better than T3
T/F
T
Thyroid hormones effects
- ___eases bmr
- ___eases heat production and oxidative metabolism
- ___eases responsiveness of heart
incr
incr
incr
Thyroid hormone is parasympathomimetic
T/F
F
sympathomimetic
Thyroid hormone is essential for normal growth of skeletal system , CNS ,ANS
T/F
T
Thyroid hormone has a permissive effect on ____ hormone ,_____ factors etc
growth
Insulin-like growth
Thyroid hormone is not involved in development of nervous system and adult activity
T/F
F
Metabolic effects of thyroid hormones
(1) Calorogenic effect : influences _____ and availability of ____
(2) Carbohydrate metabolism: ___eased glucose absorption from gut , glycogenolysis,gluconeogenesis, glucose oxidation , etc
(3) Lipid metabolism: lipo____ in adipocytes in coordination with blood glucose levels
tolerance to cold
ATP
incr
genesis
THYROID HORMONES CONTROL FUEL METABOLISM
GLYCOGENESIS
- Glycogen is a (straight or branched?) polymer of ____ stored in the ____ and ___ cells
- highly regulated by _____
branched
glucose
muscle
liver
insulin
Glycogenesis synthesis is by a seperate pathway from glycogenolysis
T/F
T
GLYCOGENOLYSIS
- breakdown of glycogen stores into ______
- hormonally controlled by _____,____,____,and____
glucose
glucagon, epinephrine, norepinephrine, and glucocorticoids
Glycogenolysis regulates blood glucose between meals
T/F
T
Glycogenolysis is suppressed by thyroid hormone
T/F
F
GLUCONEOGENESIS
- precursors are __and ___ carbon compounds Through ______
- controlled by ____ and aided by ____ hormone
- main precursor includes alanine and other AA
3 and 4
fructose phosphate
glucagon
thyroid
PROTEIN DEGRADATION
- usually balanced by _____
- can be enhanced by ____ and ____ hormones leading to gluconeogenesis
protein synthesis
glucagon
thyroid
Mention 2 energy store in the form of protein
there’s no energy store in the form of protein
Effect of thyroid hormone on nitrogen metabolism
-enhances only synthesis of proteins
T/F
F
Enhances both synthesis and degradation
excess thyroid hormone promotes protein synthesis
T/F
F
Degradation
Effect of thyroid hormone on fat synthesis
- glucose to _____ cycle
- fatty acids are ____ constantly in ____ tissue
- they become ______ or become ____ depending on ______ from _____
- requires optimal amounts of thyroid hormone
fatty acid
produced
adipose
free fatty acids
triglycerides
glycerol phosphate
glucose oxidation
Thyroid and temperature regulation
- ___ is the dominant form involved in it
- exposure to cold causes ___ conversion to__
- promotes calorogenic effects (_______)
- short term effects due to ______ effects and the _____ response of muscles
T3
Cold
T4; T3
long term cold adaptation
sympathetic mimetic
shivering
EFFECTS OF TSH
- greatly ___eases endogenous synthesis and secretion of hormone
- ___eases blood flow
- ____ effect on Glandular Tissue, RNA AND DNA synthesis(Hyperplasia), phospholipid metabolism , ETC.
incr
incr
pleiotropic
ABNORMALITIES OF THYROID FUNCTION
Hypo secretion
- _____ bmr
- ____ tolerance of Cold
- ____ of Weight
- Fatigue
- ___ and ____ Pulse
- ____ reflexes And mentation
- myxedema
- goiter
- cretinism
reduced
poor
gain
slow and Weak
slow
hyper secretion
- _____ DISEASE:
- EXOPHTALMOS
- GOITER
grave’s
TSI stands for ??
THYROID STIMULATING IMMUNOGLOBULIN
In grave’s diseases ,___ MIMICS TSH
TSI
The structures of T3 and T4 differ only by ______
a single atom of iodine
almost all hormonal output of the thyroid gland is T_
4
Thyroglobulin (TG), a glycoprotein containing large quantities of ______, is synthesized on the ____ and ______ of the thyroid follicular cells.
TG is then incorporated into secretory vesicles and extruded across the ____ membrane into the ______.
Later, the tyrosine residues of TG will be ____ to form the precursors of thyroid hormones.
tyrosine
rough endoplasmic reticulum and the Golgi apparatus
apical; follicular lumen
iodinated
In thyroid hormone synthesis
Iodine is (passively or actively ?) transported from blood into the follicular epithelial cells against both chemical and electrical gradients.
Actively
In thyroid hormone synthesis
low levels of I− (inhibits or stimulate?) the iodine pump.
Why???
Stimulate
When there is a dietary deficiency of I−, the Na+-I− cotransport increases its activity, attempting to compensate for the deficiency.
In thyroid hormone synthesis
(competitive or non-competitive ?) inhibitors of Na+-I− cotransport includes the anions _______ and ______ , which block I− uptake into follicular
Competitive
In thyroid hormone synthesis
I− is oxidized to I2 by the enzyme thyroid _____.
peroxidase
In thyroid hormone synthesis
organification of I2 into TG is catalyzed by _____
Thyroid peroxidase
Thyroid peroxidase is inhibited by ______ (__), which blocks the synthesis of thyroid hormones by blocking all of the steps catalyzed by thyroid peroxidase. Thus administration of PTU is an effective treatment for _____
propylthiouracil
PTU
hyperthyroidism.
In thyroid hormone synthesis
At the ___ membrane, just inside the lumen of the follicle, I2 combines with the tyrosine moieties of TG, catalyzed by _____, to form ——— and ———
apical
thyroid peroxidase
monoiodotyrosine (MIT)
diiodotyrosine (DIT).
MIT and DIT remain attached to TG in the follicular lumen until the thyroid gland is stimulated to secrete its hormones.
T/F
T
High levels of I− (inhibit or stimulate?) organification and synthesis of thyroid hormones
Inhibit
Effect of high levels of iodine in thyroid hormone organification is known as the ______ effect
Wolff-Chaikoff effect.
two molecules of DIT combine to form _____ .
one molecule of DIT combines with one molecule of MIT to form _____.
T4
T3
Which is faster??
Coupling reaction to get T4 or to get T3
T4
All MIT and DIT undergoe the coupling reaction to form T3 and T4
T/F
F
Hydrolysis of T4 and T3 from TG by ____ enzymes like _____
lysosomal
Proteases
MIT and DIT are also hydrolyzed from the TG complex in follicular cells
T/F
T
MIT and DIT also leave the follicular cells with T3 and T4
T/F
F
Finally , in thyroid hormone synthesis
MIT and DIT are _____ inside the follicular cell by the enzyme thyroid _____
deiodinated
deiodinase.
A deficiency of thyroid deiodinase therefore mimics ______
dietary I− deficiency.
