Patho Lecture 8 Thyroid Disorders

Thyroid structure

left/right lobes anterolateral to larynx/trachea, isthmus connect them, fibrous capsule surround

thyroid gland has bloodflow ___ times the weight of the gland every ____

5, minute

Thyroid follicles

walls of follicular cells (cuboidal epitheleal) that extend into the luminal space and secrete colloid to fill the lumen

Colloid

secreted by follicular cells in the thyroid, mainly compromised of thyroglobulin which contains T3 and T4, must be absorbed back through follicular epithelium into the blood before it can be used

two (TH) hormones produced by the thyroid

Thyroxine (T4) inactive/less potent, 93%, 4 atoms of iodine Triiodothyronine (T3) contains 3 atoms of iodine, active/potent, 7%

What is the difference between T4 and T3? (T3 has…)

T3 has 3 iodine atoms, is the active form, and 4x as potent as T4, only 7% of TH output

general thyroid hormone path

low T3/4 levels stim Thyrotropoin Releasing Hormone TRH (hypothalamus) > TSH (anterior pituitary) > TSH receptor on follicular cells > G proteins release cAMP > mediate transcription/translation > create T3/4 > peripheral cells > thyroid hormone receptors (TR) > hormone receptor complex > thyroid response elements (TRE) on genes > transcription altering gene expression > elevated TH levels inhibit process

After the TSH receptor on the thyroid gland is bound with TSH, which of the following mediates the processes that occur inside the thyroid cells?

cyclic AMP

What best describes the method that thyroid hormone uses to change function in ALL peripheral cells effected?

altering gene expression