Physiology - Thyroid Flashcards
the thyroid gland is composed of lobules of ………… follicles filled with colloid
a.hexagonal
b.spherical
c.square
b.spherical
colloid centre inside round follicle many follicles make up lobule
what are the 2 components required for thyroid hormone synthesis
a.tyrosine and calcium
b.tyrosine and iodine
c.adenosine and iodine
d.adenosine and magnesium
b.tyrosine and iodine
tyrosine + iodine —> monoiodotyrosine (MIT)
how does iodide leave the interstitial fluid and enter the follicle cell of the thyroid gland?
a.diffusion
b.active transport
c.cotransport with sodium
c.cotransport with sodium
how does iodide travel from the follicle cell into the lumen of the follicle (colloid)
a.diffusion
b.active transport
c.co transport with sodium
d.I/Cl transporter
d.I/Cl transporter
Pedrin
what happens to iodide in the colloid
iodide oxidised and attached to rings of tyrosines in the thyroglobulin
iodinated ring of one MIT is added to a DIT
what happens after iodinated tyrosine ring is added to another ring
a.endocytosis of thyroglobulin containing t3 and t4 molecules
b.lysosomal enzymes release t3 and t4 from thyroglobulin
c.thyroglobulin protein synthesised in follicle cell then sent to colloid
d.t3 and t4 released into interstitial fluid
a.endocytosis of thyroglobulin containing t3 and t4 molecules
correct sequence of events above^
in order to exert full biological activity T….. needs to be converted to T…
a.3 -> 4
b. 4 -> 3
b. 4 -> 3
which enzyme is produced in the liver, kidney, thyroid, pituitary and heart and is responsible for local synthesis of t3 and 4 in thyroid, and peripheral synthesis of t3
a.type 1 deiodinase
b.type 2 deiodinase
c.type 3 deiodinase
a.type 1 deiodinase
which enzyme is produced in the pituitary, brain, skeletal muscle and brown adipose tissue and is responsible for regulating local t3 production and adding to systemic t3 production
a.type 1 deiodinase
b.type 2 deiodinase
c.type 3 deiodinase
b.type 2 deiodinase
which enzyme is produced in the placenta, uterus, brain, fatal tissue, thyroid, kidney and adult liver and is responsible for inactivation of t3 and t4-> rt3
a.type 1 deiodinase
b.type 2 deiodinase
c.type 3 deiodinase
c.type 3 deiodinase
what type of intracellular receptor do thyroid hormones bind to?
a.cytoplasmic
b.mitochondrion joined cytoplasmic receptor and nuclear receptor
c.nuclear receptor
b.mitochondrion joined cytoplasmic receptor and nuclear receptor
binding causes increased ATP
and change in gene activity
altering structural proteins/ enzyme activity
leading to target cell response
thyroid hormones affect ALL cells in the body
what effect do t3 and t4 have on oxygen consumption
a. increase
b.decrease
a. increase
what effect do t3 and t4 have on Basal metabolic rate
a. increase
b.decrease
a. increase
what effect do t3 and t4 have on carbohydrate metabolism
a. increase
b.decrease
a. increase
increase absorption of glucose
increase glycogenolysis
increased gluconeogenesis
what effect do t3 and t4 have on lipid metabolism
a. decreased lipolysis
b.increased lipolysis
b.increased lipolysis
more circulating FFAs, increased FFA oxidation , decreases cholesterol and increases LDL receptor number
what effect do thyroid hormones have on the heart
a.increase HR,CO, increase blood flow to skin
b.decrease HR,CO, decrease blood flow to skin
a.increase HR,CO, increase blood flow to skin
what effect do thyroid hormones have on the heart
a.increase HR,CO, increase blood flow to skin
b.decrease HR,CO, decrease blood flow to skin
a.increase HR,CO, increase blood flow to skin
what effect do thyroid hormones have on the nervous system
a. increases synaptic activity , enhances effects of sympathetic NS
b.decreases synaptic activity , reduces the effects of the sympathetic nervous system
a. increases synaptic activity , enhances effects of sympathetic NS