BLD 402 EXAM 3 QUESTIONS AND ANSWERS WITH COMPLETE
SOLUTIONS GRADED A++ LATEST UPDATE
common lab test results and oberservation in uncontrolled DM both type I and II
regulation mechanism of thyroid hormone
hypothalamus-(TRH)->pituitary-(TSH)-> thyroid-(T3, T4)->Target cells
negative feedback from T3 and T4 to pituitary and hypothalamus
Explain the thyroid hormone synthesis process
There is enough dietary iodide (I-) in blood flow
Follicular cells take I- in, and then move it into colloids
Follicular cells take amino acids into cells to make thyroglobulin which is a tyrosine rich
protein. Thyroglobulin is moved out to colloid by exocytosis.
Thyroperoxidase catalyzes production of H2O2, which will be sent to colloid
Thyroidperoxide oxidizes iodide (I-) to iodine (I2). the iodine reacts with tyrosine to
thyroglobulin
Now there are mixture of monoiodotyrosine (MIT) and diiodotyrosine (DIT) within
thyroglobulin
One phenol group of MIT or DIT is added to another phenol group of DIT within
thyroglobulin (coupling)
T3 and T4 within thyroglobulin (with unused MIT, DIT) will be stored in colloid
T3 and T4 within thyroglobulin (with unused MIT, DIT) will come back in the follicular
,cell by endocytosis when thyroid hormone is needed.
Lysosomal proteases hydrolyze thyroglobulin into T3, T4, iodide and other amino acids.
Iodide and other amino acids will be recycled
T3, T4 are secreted from follicular cells
What is the difference between free and bound thyroid hormone
free: active forms; has a biological effect
bound: bound to protein, prevents them from reacting with other enzymes or renal
excretion. typical binding protein: thyroxine binding globulin (TBG)- about 80% is bound
to this
T3
three iodines on structure
only 5% of production; more stimulating effect
genomic action: thyroid hormone binds to to a receptor and the complex binds to DNA.
the complex on the DNA will lead to transcription (T3 is more potent)
T3 is 10 times more potent than T4 so free T3 is most potent
T4
Four Iodines on structure
95% of production in thyroid, "precursor"
, nongenomic action: receptor is on the cell membrane. this mechanism supports
trafficking transcription related material to nucleus. (T4 is more potent)
explain the process of conversion of T4 to T3
in the target tissue (liver, kidney, brain, muscle, etc) T4 is converted to T3 or rT3 by
deiodinase. some T3 will be used right away; some T3 will go to blood flow. the reverse
T3 is inactive.
Graves' disease
Hyperthyroidism
T3/T4 are increased so TSH decreases by feedback
cause: anti-TSH receptor antibody binds to receptor and stimulates thyroid all the time
Hashimoto's disease
acquired hypothyroidism: T3/T4 low
(lymphocytic thyroiditis)
cause: anti-thyroid peroxidase: (+) in most case
anti-thyroglobulin: (+) in 20-50% of cases
accumulation of lymphocyte-> complication- B cell lymphoma is some cases
diagnostic tests after T3/T4 decrease, TSH increases result
SOLUTIONS GRADED A++ LATEST UPDATE
common lab test results and oberservation in uncontrolled DM both type I and II
regulation mechanism of thyroid hormone
hypothalamus-(TRH)->pituitary-(TSH)-> thyroid-(T3, T4)->Target cells
negative feedback from T3 and T4 to pituitary and hypothalamus
Explain the thyroid hormone synthesis process
There is enough dietary iodide (I-) in blood flow
Follicular cells take I- in, and then move it into colloids
Follicular cells take amino acids into cells to make thyroglobulin which is a tyrosine rich
protein. Thyroglobulin is moved out to colloid by exocytosis.
Thyroperoxidase catalyzes production of H2O2, which will be sent to colloid
Thyroidperoxide oxidizes iodide (I-) to iodine (I2). the iodine reacts with tyrosine to
thyroglobulin
Now there are mixture of monoiodotyrosine (MIT) and diiodotyrosine (DIT) within
thyroglobulin
One phenol group of MIT or DIT is added to another phenol group of DIT within
thyroglobulin (coupling)
T3 and T4 within thyroglobulin (with unused MIT, DIT) will be stored in colloid
T3 and T4 within thyroglobulin (with unused MIT, DIT) will come back in the follicular
,cell by endocytosis when thyroid hormone is needed.
Lysosomal proteases hydrolyze thyroglobulin into T3, T4, iodide and other amino acids.
Iodide and other amino acids will be recycled
T3, T4 are secreted from follicular cells
What is the difference between free and bound thyroid hormone
free: active forms; has a biological effect
bound: bound to protein, prevents them from reacting with other enzymes or renal
excretion. typical binding protein: thyroxine binding globulin (TBG)- about 80% is bound
to this
T3
three iodines on structure
only 5% of production; more stimulating effect
genomic action: thyroid hormone binds to to a receptor and the complex binds to DNA.
the complex on the DNA will lead to transcription (T3 is more potent)
T3 is 10 times more potent than T4 so free T3 is most potent
T4
Four Iodines on structure
95% of production in thyroid, "precursor"
, nongenomic action: receptor is on the cell membrane. this mechanism supports
trafficking transcription related material to nucleus. (T4 is more potent)
explain the process of conversion of T4 to T3
in the target tissue (liver, kidney, brain, muscle, etc) T4 is converted to T3 or rT3 by
deiodinase. some T3 will be used right away; some T3 will go to blood flow. the reverse
T3 is inactive.
Graves' disease
Hyperthyroidism
T3/T4 are increased so TSH decreases by feedback
cause: anti-TSH receptor antibody binds to receptor and stimulates thyroid all the time
Hashimoto's disease
acquired hypothyroidism: T3/T4 low
(lymphocytic thyroiditis)
cause: anti-thyroid peroxidase: (+) in most case
anti-thyroglobulin: (+) in 20-50% of cases
accumulation of lymphocyte-> complication- B cell lymphoma is some cases
diagnostic tests after T3/T4 decrease, TSH increases result
