Flashcards in Endocrine Physiology Deck (9)
Which of the following is true regarding thyroid hormones?
a. acts on nuclear receptors
b. utilizes G proteins as 2nd messengers
c. activates preformed enzymes
d. A and B
e. A and C
A. acts on nuclear receptors
Thyroid hormones are protein hormones which act like lipid hormones in terms of binding, mechanism of action, and effect on enzyme activation / synthesis.
They traverse the membrane to act on nuclear receptors and promote synthesize of new hormones.
Handout page 94
Enumerate 3 examples of positive feedback in endocrine organs.
oxytocin surge during delivery
oxytocin surge during lactation
LH and FSH surge during ovulation
True or False
Binding of GDP to the alpha subunit of the G protein complex inactivates the protein.
Binding to GTP activates the protein.
Recite the cascade of events in the cyclic AMP messenger system.
GTP binds to alpha subunit of G protein
G protein activates adenylate cyclase
AC converts ATP to cyclic AMP
cAMP activates protein kinase A
PKA activates target enzymes
Alpha > AC > ATP > cAMP > PKA
The IP3/DAG messenger system is used by all hypothalamic hormones EXCEPT:
The neurohypophysis produces which hormone/s?
e. A and B
f. C and D
The neurohypophysis / posterior pituitary does not produce any hormone. It just stores and secretes ADH and OXYTOCIN produces in the HYPOTHALAMUS.
Which enzyme promotes cell growth and division on the target tissues or organ?
Enumerate at least 3 protein products derived from POMC.