EXAM 1 BIOS 255 2026 PRACTICE TEST WITH
STEP BY STEP SOLUTIONS
◉ synthesis of T3 and T4. Answer: endocytosis of colloid,
proteolysis=digestion, transport out of the cell
◉ iodine-131=radioactive isotope. Answer: concentrates in thyroid-
> thyroid cancer
◉ combate radioactive iodine-131 by. Answer: taking iodide pills->
saturate thyroid w normal iodide, then eliminated in urine
◉ T3 and T4 are. Answer: lipid-soluble
◉ TBG=thyroxine-binding globulin. Answer: main carrier, both T3
and T4
◉ Blood transport proteins. Answer: T3/T4, TBG, Transthyretin,
serum albumin
◉ <1%=. Answer: free T3 and T4
,◉ T3 is ___ times more active than T4.. Answer: 5X
◉ T4 converted to T3 in:. Answer: liver, kidneys, and other tissues
◉ T3 and T4 targets. Answer: almost all tissues ex) brain, liver, bone,
heart
◉ effects of T3/T4. Answer: increase basal metabolic rate
-BMR(awake, resting, fasting)
-More calories burned
-More heat=calorigenic effect
increase body heat
◉ T3/T4 increase basal metabolic rate by. Answer: increased
synthesis of
-Na+/K+ pumps
-aerobic respiration enzymes
increased # & activity of mitochondria
◉ during childhood, development of:. Answer: bone, nervous tissue
◉ hypothyroidism. Answer: low levels of T3 and T4
, in childhood it stunts bones & causes mental disabilities
◉ Thyroid stimulating hormone hormone(TSH)
aka thyrotropin. Answer: -released by anterior pituitary
-stimulates production and release of T3/T4
◉ thyrotropin-releasing hormone (TRH). Answer: -secreted by
hypothalamus into hypophyseal portal system
-stimulates release of TSH by anterior pituitary
◉ hormone cascade. Answer: -TRH->TSH->T3/T4
-low T3/T4 in blood
-hypothalamic-pituitary-thyroid axis
◉ negative feeback. Answer: increased T3/T4 reduces TRH and TSH
◉ effects of TSH on follicle cells. Answer: -increased production of:
--iodine transporter
--thyroglobulin
--thyroid peroxidase
-increased endocytosis & digestion of colloid
-increased cell proliferation
STEP BY STEP SOLUTIONS
◉ synthesis of T3 and T4. Answer: endocytosis of colloid,
proteolysis=digestion, transport out of the cell
◉ iodine-131=radioactive isotope. Answer: concentrates in thyroid-
> thyroid cancer
◉ combate radioactive iodine-131 by. Answer: taking iodide pills->
saturate thyroid w normal iodide, then eliminated in urine
◉ T3 and T4 are. Answer: lipid-soluble
◉ TBG=thyroxine-binding globulin. Answer: main carrier, both T3
and T4
◉ Blood transport proteins. Answer: T3/T4, TBG, Transthyretin,
serum albumin
◉ <1%=. Answer: free T3 and T4
,◉ T3 is ___ times more active than T4.. Answer: 5X
◉ T4 converted to T3 in:. Answer: liver, kidneys, and other tissues
◉ T3 and T4 targets. Answer: almost all tissues ex) brain, liver, bone,
heart
◉ effects of T3/T4. Answer: increase basal metabolic rate
-BMR(awake, resting, fasting)
-More calories burned
-More heat=calorigenic effect
increase body heat
◉ T3/T4 increase basal metabolic rate by. Answer: increased
synthesis of
-Na+/K+ pumps
-aerobic respiration enzymes
increased # & activity of mitochondria
◉ during childhood, development of:. Answer: bone, nervous tissue
◉ hypothyroidism. Answer: low levels of T3 and T4
, in childhood it stunts bones & causes mental disabilities
◉ Thyroid stimulating hormone hormone(TSH)
aka thyrotropin. Answer: -released by anterior pituitary
-stimulates production and release of T3/T4
◉ thyrotropin-releasing hormone (TRH). Answer: -secreted by
hypothalamus into hypophyseal portal system
-stimulates release of TSH by anterior pituitary
◉ hormone cascade. Answer: -TRH->TSH->T3/T4
-low T3/T4 in blood
-hypothalamic-pituitary-thyroid axis
◉ negative feeback. Answer: increased T3/T4 reduces TRH and TSH
◉ effects of TSH on follicle cells. Answer: -increased production of:
--iodine transporter
--thyroglobulin
--thyroid peroxidase
-increased endocytosis & digestion of colloid
-increased cell proliferation
