Thyroid Flashcards
nervous connection
hypo to posterior pituitary gland
humoral connection
hypo to anterior pituitary
anatomic connection
pituitary stalk
aka “infundibulum”
arcuate nucleus
Thyroid
collection of cells in the hypothalamus
anterior pituitary
contains thyotropes
posterior pituitary
secretes ADH and oxytocin
thyrotropes
cells in A.P that have 1 on 1 connection with the thyroid
HP thyroid axis
arcuate nucleus-> source of signal-> TRH
TRH
thyrotropin releasing hormone
gets released into PS and through blood vessels to AP and interacts with receptors on thyrotropes
hypothalamo hypophyse portal system
efferent blood one system (hypothalamus) becomes afferent blood in another system (AP)
unidirectional, maybe bidirectional
TSH
thyroid stimulating hormone
polypeptide excreted by exocytosis
iodine
essential for production of TH
TSH binds to receptor
- increase sodium iodide symporter
- increase pendrin
- thyroperoxidase (TPO) upregulation (generates H2O2)
- organification
- conjugation of DIT and MIT
- pinocytosis
- secretion
T3 more lipophilic than T4
true
transthyretin
chaperone
doesn’t bind with covalent bonds
tronbthyrectin
T-binding globulin
affinity for T4
south of neck=
long negative feedback
if cannot regulate negative feedback
hypothyroidism
long loop negative feeback
T3/T4 in bloodstream inhibits TRH at hypothalamus
TRH stimulates
thyrotropes in anterior pituitary in order to make T3/T4
ultra short negative feedback
TRH will go from ap to hypothalamus to regulate its own secretion
colloid
TSH bind to receptor
cAMP will stimulate adenylate cyclase
TRH bind to receptor
stimulates GPCR
phospholipase produces DAG and IP3
DAG makes protein kinase C, IP3 enters SR to release calcium and cause exocytosis
