Thyroid + ETC Flashcards
State which hormones correspond to hypothalamic-pituitary-thyroid axis
TRH (hypothalamus)
TSH (anterior pituitary)
T4/T3 (thyroid)
What is initial test to look for hyperthyroid or hypothyroid?
TSH
*need to interpret in context
How are T3 and T4 transported through blood? Why?
bound to TBG since they are hydrophobic
TSH effects
activates G-protein coupled receptor on follicular cell membranes
Gs makes cAMP which activates thyroid hormone synthesis
Thyroid hormone receptors
located on nuclear receptors on the nucleus
What increases BMR? What increases sympathetic nervous system? (both increased by thyroid hormone)
more Na/K+ ATPase (BMR)
more B1-adrenergic receptors
Colloid
a stored form of iodinzed thyroglobin
stored in the follicles
How does colloid get transported for use?
needs to be endocytosed back into the follicular endothilieal cell
Hypothyroidism lab values
high TSH w/ low free T4
*TSH is signaling for more thyroid hormone, but it is not working
Hyperthyroidism lab values
despite low TSH, free T4 remains high
Hypopituitary lab values
low TSH and low T4
*pituitary gland is not appropriately responding to thyroid hormone conditions
Pregnancy lab values
low TSH and high T4
Critical illness / starvation lab values
low TSH with mildly abnormal T4
*function returns to normal after illness is over
Carboxyhemoglobin
when CO binds heme instead of O2
Cytochrome C
also known as complex IV
has both Fe3+ and Fe 2+
when Fe3+ is reduced to Fe 2+, it then donates some protons to O2 to form H2O
Where does anaerobic fermentation always occur?
RBCs since they have no mitochondria
Typical path of aerobic energy production (broad strokes)
glucose goes through glycolysis to form pyruvate
pyruvate becomes NADH and FADH2
goes through ETC to make ATP
Typical path of anaerobic energy production
glucose goes through glycolysis to form pyruvate
pyruvate cannot go to ETC
Pyruvate is reduced to lactate instead
When pyruvate is reduced, what gets oxidized?
both lactate and NADH
ATP synthase
highly conserved complex to harvest chemoelectric potential of protons
protons go from intermembrane space to mitochondrial matrix
What can inhibit ATP synthase?
oligomycin
Where does CO bind?
to Fe2+ in both Hbg and ETC
has great affinity for heme
blocks ETC which causes more lactate fermentation
Brown adipose tissue
uncoupling agent of ETC
uncouples movement of protons from ATP synthase (now everything goes to heat)
What causes weight loss ?
conversion of calories into heat
How does thyroid hormone activate brown adipose?
increases mitogenesis
increases UCP1
UCP1
uncoupling protein 1 that works with brown adipose tissue
What subunit rotates in ATP synthase?
the F1 subunit
When does prolactin increase?
prolactin is produced with TSH
therefore, in hypothyroidism when TSH increases, so does prolactin
Why does glucose increase with hyperthyroidism?
need more blood glucose to fuel the excess energy production associated with hyperthyroidism
