Thyroid/Parathyroid Gland Flashcards
thyroid gland is located in ______
the front of the neck
thyroid gland is shaped like a _____
butterfly
the thyroid gland has two lobes connected by ______
a bridge of tissue
the thyroid gland has a high rate of _____ per gram of tissue
blood flow
the thyroid gland consists of multiple _____
follicles
each follicle in the thyroid gland is surrounded by a single layer of _____
polarized epithelial cells: thyrocytes
each follicle in the thyroid gland is filled with _____
colloid
colloid consists of ________
thyroglobulin
thyroglobulin is the precursor of ______
thyroid hormones
thyroglobulin provides _____ residues
tyrosine
thyroglobulin is synthesized in ______
thyrocytes
thyrocytes are enriched with _____
endoplasmic reticulum
thyrocytes respond to ___
TSH
thyrocytes secrete thyroglobulin into colloid for ____
T3/T4 synthesis
_____ residues in thyroglobulin are precursors of thyroid hormones
tyrosine
_____ is an essential raw material for thyroid hormone synthesis
iodine
__ is the primary/ most abundant hormone secreted by the thyroid (medical use)
t4
__ has greater biological activity than t4, but lesser amounts
t3
___ is not biologically active, and there are lesser amounts of it
RT3
_____ is the enzyme that removes iodine group
deiodinase
_____ is the enzyme that converts tyrosine to thyroxine (T4) or triiodothyronine (T3)
thyroid peroxidase (TPO)
dietary iodide is absorbed by ____ and enters the circulation
intestine
the principal organ that takes up the circulating I is the _____
thyroid; uses it to make thyroid hormones
circulating T3 and T4 are metabolized in _____
the liver and other tissues
excretion of thyroid hormones is predominantly in _____
urine; a small amount in stool
the thyroid secretes ____ in the form of T4>T3
80 ug/d
____ exchanges I to colloid area for Cl
pendrin
___ transports I and Na to thyrocytes
NIS (Na+/I- symporter)
a transporter called ___ releases thyroid hormones into the bloodstream to hit the target
MCT (monocarboxylate transporter)
thyroid hormone receptors are ____ receptors
nuclear
which cells in the body are targets for thyroid hormones
all
thyroid hormones stimulate ________, leading to increased concentrations of fatty acids in plasma
fat mobilization
thyroid hormones enhance ____ of fatty acids in many tissues
oxidation
thyroid hormones decrease plasma concentrations of _______
cholesterol and triglycerides
thyroid hormones stimulate almost all aspects of ______ metabolism
carbohydrate
thyroid hormones enhance _________ into cells
insulin-dependent entry of glucose
thyroid hormones increase _____ and _____ to generate free glucose
gluconeogenesis, glycogenolysis
T3 and T4 are usually bound to _______
thyroxine binding globulin (TBG)
which deiodinase is highly concentrated in the liver, kidneys, thyroid, and pituitary
D1
which deiodinase is highly concentrated in the brain, pituitary, and brown fat
D2
which deiodinase is highly concentrated in the brain and reproductive tissues
D3
thyroid function is regulated primarily by the circulating level of ___
TSH
TSH is produced in _____
pituitary
TSH production is inhibited by ____
negative feedback of free T4 and T3
TSH secretion is regulated by ______
thyrotropin-releasing hormone (TrH)
TrH is produced in ______ dependent on whole body status
hypothalamus
TSH increases _____ flow on the thyroid
blood
TSH increases ____ uptake by regulating NIS
iodide
TSH increases secretion of _____ into the colloid
thyroglobulin
TSH increases synthesis of _____
T3/T4 (thyroid peroxidase, TPO)
TSH increases ______ of colloid
endocytosis; increases releasing of T3 and T4
whenever TSH stimulation is prolonged, the thyroid becomes ____
enlarged
______ is inadequate production of thyroid hormones
hypothyroidism
_______ is overproduction of thyroid hormones
hyperthyroidism
the most common cause of hypothyroidism is ______
iodine deficiency
6 causes of hypothyroidism
iodine deficiency, thyroid dysgenesis, inborn errors of synthesis, thyroiditis, thyroidectomy/radiation, hypopituitary
_____ is inflammation of the thyroid gland
thyroiditis
over 90% of goiter cases are caused by ______
iodine deficiency
when insufficient T4 and T3 are produced due to no iodine, there is no inhibition on the hypothalamus-> anterior pituitary-> thyroid, causing the thyroid to grow forming _____
goiter
_____ treats iodine deficiency
iodized salt
goiter, fatigue, weakness, mental slowing, poor memory and concentration, depression, weight gain, feeling cold, hair loss, reproductive failure, plasma cholesterol increase, and growth/developmental issues are symptoms of _____
hypothyroidism
______ is surgical removal of all or part of the thyroid gland
thyroidectomy
thyroidectomy leading to hypothyroidism is treated by ______
hormone replacement: oral administration of synthetic thyroid hormone (T4) which mimics the physiological condition
5 causes of hyperthyroidism
graves disease, thyroid adenoma, hyperpituitary, excess iodine consumption, taking too much T4 or thyroid tissue
_____ is the most common cause of hyperthyroidism
grave’s disease
grave’s disease is more common in _____
females
increased appetite, weight loss, muscle weakness, insomnia, fast heartbeat, poor tolerance of heat, excessive sweating, diarrhea, bulging eyes, goiter, hand tremor, and hair loss are symptoms of ____
hyperthyroidism
the mechanism of graves disease is caused by high levels of _____ and a low ___ level
high levels of circulating thyroid hormones and a low TSH level
graves disease causes the thyroid to be ___
enlarged
graves disease causes _____ of the thyroid gland
hyperplasia
3 ways to treat graves disease
antithyroid drugs, radioiodine, surgery
antithyroid drugs suppress synthesis of T3/T4 by inhibiting ______
thyroid peroxidase (TPO)
two antithyroid drugs are ____ and _____
propylthiouracil (PTU), methimazole (MMI)
radioiodine is highly selective because of pickup by ___
NIS
methimazole targets ___
TPO (thyroid peroxidase)
propylthiouracil targets ____
deiodinase
____ can disturb the homeostasis of thyroid hormones
drugs
there are ___ parathyroid glands
four
each parathyroid gland is a ______
richly vascularized disk
the two types of cells in parathyroid gland are ____ and ____
chief cells, oxyphil cells
chief cells contain a dominant ______ plus endoplasmic reticulum and secretory granules
golgi apparatus
chief cells synthesize and secrete ______
parathyroid hormone (PTH)
_____ cells are less abundant, larger, and have an unknown function
oxyphil
parathyroid hormone (PTH) is a linear _______
polypeptide
PTH increases plasma ___
Ca2+
PTH decreases plasma _____
phosphate
PTH increases _______ and mobilizes Ca2+, therefore increasing plasma Ca2+
bone resorption
PTH increases reabsorption of Ca2+ in the _____
kidney
PTH increases the formation of __________ which increases Ca2+ absorption from the intestine
1,25-dihydroxycholecalciferol (1,25-OH2 D3)
PTH increases ____ excretion in the kidney (decrease reabsorption)
phosphate
calcitonin is a ___ lowering hormone (decreases plasma conc)
Ca2+
calcitonin is produced by ______ cells of the thyroid gland
parafollicular cells (C cells)
parathyroidectomy is an accident in thyroid surgery that causes _______
hypoparathyroidism; severe consequences)
parathyroidectomy causes a decline in ______ because of low PTH
plasma Ca2+ level
parathyroidectomy usually causes plasma phosphate levels to ____
rise
symptoms of low plasma Ca2+ are _______
neuromuscular hyperexcitability
four treatments for parathyroidectomy
calcium supplementation, vitamin D analogs, synthetic PTH, synthetic T4