PBIO LECT 20

• underactive thyroid

• caused by autoimmune disorder

• high TSH but low T3 & T4

• possible goiter

Hashimoto thyroiditis (hypothyroidism)

• overactive thyroid

• caused by autoimmune disorder

• low TSH

• Possible goiter

Graves disease (hyperthyroidism)

__ which is normally quite low, goes up in both hypo & hyperthyroidism & can be tested for

plasma thyroglobulin

both __ & __ are acquired from diet

iodine & tyrosine

__ provides tyrosine for the conjugation

thyroglobulin

__ both iodinates & couples the tyrosine→ makes T3 & T4

thyroid peroxidase (TPO)

allows I- to enter the colloid (inner most cell)

pendrin

(thyroid hormones)

• made at hypothalamus

TRH

(thyroid hormones)

• secreted by anterior pituitary

TSH

(thyroid hormones)

• secreted by thyroid gland

T3 & T4

the “active” for of thyroid hormones

T3

Like the steriod hormones, thyroid hormones use __ to turn on gene transcription

nuclear receptors

applies to individuals born and living in areas of severe iodine deficiency and endemic goiter exhibiting irreversible anomalies of intellectual and physical development not explained by other causes than the environmental factors responsible for goiter

endemic cretinism

• defects in thyroid hormone synthesis are responsible for most cases now; problems with hypothalamus or pituitary (central)

• Rapid T4 administration within 7-14 days of birth can rescue these cases

congenital hypothyroidism

this feedback loop is for __

hyperthyroidism

this feedback loop is for __

hypothyroidism

What is the protein that serves as the backbone for Thyroid hormone synthesis?

thyroglobulin

how does thyroglobulin get into the follicular lumen?

exocytosis