T4,T3and TSH - kentictac

[ArchivalUser]

which one create Negative feedback to hypothalamus and anterior pituitary?
1_ T4
2_ T3
3_TSH

[ArchivalUser]

11

[ArchivalUser]

anyone exaplains

[ArchivalUser]

my ans is T4 but I am not sure , Kaplan Phys said thhe ratio T3 and T4 1:50 and main circulating is T4 but when T4 is taken by the thyrotroph it must be converted to T3 before creating negative feedback
If anyone know more and clear please explain , small point but good point to know
Thanks

[ArchivalUser]

In general, both elevated levels of T3 and T4 suppress the production of TSH via a classic negative feedback mechanism. Recent evidence also indicates that somatostatin and dopamine exert inhibitory control over TSH release, suggesting that the hypothalamus may provide both inhibitory and stimulatory influence on pituitary TSH production.