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;
77 Cards in this Set
- Front
- Back
|
What are the hormones released by the thyroid gland?
|
T3/T4
calcitonin |
|
|
What am I:
amino acid residues of T3/T4 that is synthesized and stored in thyroid gland |
thyroglobulin
|
|
|
What is the active form of T3/T4?
|
L-isomers (T3)
|
|
|
What is the essential part of thyroid hormones?
|
iodine
|
|
|
What is more potent, T3 or T4?
|
T3
|
|
|
What do T3 and T4 do?
|
increase uptake of glucose and amino acids
T3 increase protein synthesis by binding to cytoplasmic binding protein |
|
|
What is the thyroid gland made up of?
|
follicles made up of thyroid follicular cells
|
|
|
Where is thyroglobulin located in the thyroid?
|
inside thyroid follicles
associated with inner surface of follicles |
|
|
What is thyroglubulin made up of?
|
throxine (T4) and triiodothyronine (T3) linked together by peptide bonds
|
|
|
Where is thyroglobulin synthesized?
|
colloid/cell interface of thyroid gland
|
|
|
What are the steps in thyroid hormone synthesis?
|
1. uptake of iodide
2. iodide organification 3. coupling of MIT adn DIT 4. secretion of thyroid hormones 5. conversion of T4 to T3 |
|
|
What step of the thyroid hormone synthesis are drug targets?
|
iodide organification
|
|
|
What stimulates the uptake of iodide into the thyroid follicular cell?
|
TSH
|
|
|
What inhibits the uptake of iodide into the thyroid follicular cell?
|
monvalent anions:
perchlorate, thiocyanate, pertechnetate |
|
|
Where does iodid organification occur?
|
in thyroid follicular cell
|
|
|
What enzyme oxidizes iodide into iodine?
|
thyroid peroxidase
|
|
|
What inhibits the oxidation of idodide into iodine?
|
thionamides
|
|
|
How is MIT and DIT formed?
|
iodine iodinates tyrosine redisue in thyroglobulin
|
|
|
What enzyme is involved in the coupling of MIT and DIT?
|
thyroid peroxidase
|
|
|
What am I:
coupling of MIT and DIT |
T3
|
|
|
What am I:
coupling of DIT and DIT |
T4
|
|
|
What is the ratio of T4 to T3 synthesized?
|
5 T4 to 1 T3
|
|
|
What structure is important in the coupling of MIT and DIT?
|
NH-CH-COOH
|
|
|
What inhibits the synthesis of T3/T4?
|
thionamides
|
|
|
How is T3/T4 released?
|
endocytosis of TG/colloid from follicular lumen
fusion of lysosomal granules containing proteolytic enzymes proteolysis of TG releases T4/T3 |
|
|
What proteins do T4/T3 bind to to protect against metabolism?
|
thyroxine binding globulin (mostly) and transthyretin (less affinity)
|
|
|
What are the abnormal stimulators of TSH?
|
graves disease
tumors |
|
|
What am I:
results in production of thyroid stimulating immunoglobuin mimics action of TSH but last longer |
Grave's disease
|
|
|
What am I:
cause excessive hormone production resulting in the abnormal stimulation of thryoid gland |
thyrotoxicosis
|
|
|
What am I:
deficiet in iodine failure of thyroid to develop dwarfism, mental retardation, pale skin, slow heart rate, low body temperature |
cretinism
|
|
|
What are the most sensitive tissues that are affected by thyroid hormone?
|
heart, skeletal muscle, liver, kidneys
|
|
|
This disease is characterized by thyrotoxicosis and opthalmopathy (exophtalmos)
|
grave's disease (diffuse toxic goiter)
|
|
|
This disease arises from long-standing non toxic goiter resulting in hyperexcretion of thyroid hormones
|
plummer's disease (toxic nodular goiter)
|
|
|
What is the treatment for thyroid storm?
|
propranolol
|
|
|
What is thyroid storm?
|
high excess of T3/T4 at one time
|
|
|
These are agents that decrease production of thyroid hormones
|
goitrogens
|
|
|
What drugs are thionamides?
|
methimazole
propylthiouracil carbimazole |
|
|
What is the MOA of thionamides?
|
inhibit thyroid peroxidase from catalyzing organification and MIT/DIT coupling
inhibits peripheral de-ionization of T4 to T3 |
|
|
What are Thionamides used for?
|
hyperthyroidism
|
|
|
What are the side effects of thionamides?
|
agranulocytosis
|
|
|
What are anti-thyroid hormone drugs used for?
|
diagnostic indicator
|
|
|
What am I:
resemble iodide reversible competitive inhibitor of iodide transport into thyroid |
monovalent anions:
perchlorate pertechnetate thiocyanate |
|
|
What am I:
oldest remedy for hyperthyroidism inhibits TH release and organification of iodide decrease size and vascularity of hyperplastic gland |
iodide
|
|
|
What am I:
emit beta radiation to destroy thyroid gland |
radioactive iodine (I 131)
|
|
|
What is the disadvanatage of I131?
|
delayed hypothryoidism
|
|
|
What am I:
inhibit coversion of T4 to T3 in liver, kidney, pituitary and brain used for diagnostic testing only |
ipodate
iopanoic acid |
|
|
What disease am I:
autoimmune destruciton of thyroid gland |
hashimoto's thyroiditis
|
|
|
What disease am I:
due to thyroid hormone deficiency can lead to myxedema |
gull's disease
|
|
|
What am I:
am made of T3 3-4X more potent than levothyroxine shorter half life (24 hours) |
liothyronine
|
|
|
What am I:
made of T4 that is converted into T3 by body |
levothyroxine
|
|
|
What am I:
due to extracellular calcium falling below normal - leads to progressively more excitable nervous system because of increase in sodium permeability |
hypercalcemic tetany
|
|
|
What regulates the secretion of hormones/neurotransmitter?
|
calcium
|
|
|
What is the precursor to PTH?
|
preproparathyroid hormone
|
|
|
Where is preproparathyroid hormone synthesized?
|
parathyroid gland chief cells
|
|
|
What serves as a secondary mechanism that feeds back to reduce PTH secretion?
|
Vit D
|
|
|
At what concentration of Calcium does maximun secretion of PTH occur?
|
< 3.5
|
|
|
At what concentration of Calcium is PTH secretion maximally inhibited?
|
> 5.5
|
|
|
What are the effects of PTH on the bone?
|
stimulates osteoblast
stimulates bone resorption |
|
|
what are the effects of PTH on the kidney
|
increase reabsorption of Ca
reduce reabsorption of Phosphorous activates Vit D activating enzyme |
|
|
What are the effects of PTH on the intestine?
|
indirectly increase Ca absorption via Vit D
|
|
|
Where does PTH increase calcium and mag reabsorption?
|
ascending loop
distal tubule |
|
|
where dose PTH increase Cl reabsorption?
|
proximal tubule
|
|
|
Where does PTH decrease phosphate, NA, and Bicar reabsorption?
|
proximal tubule
|
|
|
What enzyme is responsible for the activaton of Vit D
|
1 alpha-hydroxylase
|
|
|
What is the rapid phase of calcium absorption through the intestine?
|
1-6 hours by increasing Na/Ca exchange
|
|
|
What is the slow phase of calcium absorption in the small intestine?
|
48-96 hours by increasing synthesis of calcium binding proteins (calbindins)
|
|
|
What part of the bone have Vit D receptors?
|
osteoblast
|
|
|
How dose Vit D increase Ca resorption from the bone?
|
activates osteoblast to produce paracrine signal that activates osteoclast to resorb Ca
also stimulates osteocytic osteolysis |
|
|
What are the underlying causes of hypercalcemia?
|
vit D synthesis by lymphomas
local osteolytic hypercalcemia humoral hypercalcemia (over expression of PTH-related protein) |
|
|
What am I:
due to activating mutation of PTH receptor - activation of receptor in absence of hormone characterized by hypercalcemia, hypophosphatemia, short-limbed dwarfism |
jansen's metaphyseal chondrodysplasia
|
|
|
This condition is due to inadequate response of vitamin D-PTH axis to hypocalcemic stimuli
|
hypocalcemia
|
|
|
This disease is due to a defect in PTH receptor-adenylate cyclase complex (mutation of Galpha subunit). Mimics loss of PTH
|
pseudohypoparathyroidism
|
|
|
Patienst with pseudohypoparathyroidism is also resistant to what?
|
TSH, glucagon, gonadotropins
|
|
|
This drug activates the calcium sensing receptor.
|
cinacalcet
|
|
|
This drug inhibits sodium reabsorption and increase calcium reabsorption
|
thiazides
|
|
|
This drug is a vit D metabolite capable of raising serum calcium levels within 24-28 hours
|
calcitriol
|
|
|
These drugs can be used to treat secondary hyperparathyroidism of chronic kidney disease
|
doxercalciferol
paricalcitrol |
