Endocrine - Hormones II (Anterior Pituitary and Thyroid) Flashcards
What is the master control center of the endocrine system?
Hypothalmus
What is the target organ of the hypothalamus?
Pituitary
What stimulates TSH production? Where is it produced?
TRH - thyrotropin releasing hormone
Hypothalmus
What stimulates PRL (prolactin) production? Inhibits it?
PRF - prolactin releasing factor
PIH - prolactin release-inhibiting hormone
What stimulates ACTH production?
CRH - corticotropin releasing hormone
What stimulates both LH and FSH?
GnRH - gonagotropin releasing hormone
What stimulates GH? Inhibits GH?
GHRH - stimualtes
SS - inhibts
What portion of the hypothalamic releasing hormones prevents degredation and lengthens half-life?
Cyclic N-terminal
Are hormones of the anterior pituitary made on demand or made and stored? How are they released
Made and Stored in pre-existing vesicles
Vesicles exocytosed after stimulated by hormones from hypothalamus
What three tissues does GH directly affect? Which tissue does it act on primarily to release IGF1?
Bone, Muscle, Adipose
Liver - primary source of LGF1
What hormones act through the JAK/STAT (nonreceptor tyrosine kinase) pathway? PIGG(L)ET
Prolactin Immunomodulators GH G-CSF Erythropoietin Thrombopoietin
How does the Jak/STAT kinase cascade begin?
Ligand binds to receptor
Receptor dimerizes upon hormone binding
Jaks phosphorylate as a result of dimerization
Jaks phosphorylate intracellular domains
STAT phoshphorylated by intracellular domain
Dimerization of stat and nuclear translocation
What does it mean the TSH, FSH, and LH are all glycoproteins?
All are glycosylated
Which subunit of g-protein receptors are the same? Which subunit is different? What does this allow?
Alpha - same subunit across receptors
Beta - different
Beta confers biologic activity of receptor
Is the Beta subunit active in the absence of the alpha-subunit?
No
What hormones are considered Gs, adenylyl cyclase stimulated cAMP pathway? FLAT ChAMP
FSH LH ACTH TSH CRH hCG ADH MSH PTH
How does the Gs protein coupled receptor pathway tranduce a signal?
Binding of hormone to g-coupled receptor activates adenylyl cyclase
Adenylyl cyclase uses ATP to corm cAMP
cAMP acts on R2C2 (inactive PKA) and binds to R2, releasing it from PKA
C2 (PKA) now active and can phosphorylate proteins
What is secreted from the intermediate lobe of the pituitary?
Pro-opiomelanocortin (POMC)
What hormones are derived from POMC?
ACTH
MSH
Lipotropin
Endorphins
How is POMC processed?
Processed at tissue level to generate hormones
ACTH - anterior pituitary
MSH - stimulates melanin synthesis at skin, produced in intermediate lobe of anterior pituitary
How do hormones of the posterior pituitary differ from those of the anterior pituitary?
Hormones only stored in posterior pituitary. They are made in hypothalmus
What two hormones are released by the posterior pituitary?
Oxytocin
ADH (vasopressin)
What are neurophysins? What are they associated with?
Carrier proteins
Associated with oxytocin and vasopressin
What concentrates iodide in thyroid cells?
Na/K ATPase pump
What oxidizes Iodide to iodine?
Thyroperoxidase
What catalyzes the addition of iodine to thyroglobulin? What does this produce?
Thyroperoxidase Produces MIT (monoiodotyrosyl) and DIT (diiodotyrosyl) residues
How are T3 and T4 formed?
Combining MIT and PIT residues on thyroglbulin
After iodinated thyroglobulin is formed, where is it taken to?
Taken up in vesicles by thyrocytes and fuses with lysosomes
What degrade thyroglobulin, releasing AA, T3, and T4? Where are T3 and T4 secreted?
Lysosomal proteases degrade thyroglobulin
T3 and T4 released into circulation
Are thyroid hormones hydrophilic or hydrophobic?
Hydrophobic
What are TBG and TBPA?
Carrier proteins for thyroxin
What are T3Rs? Where are they found? What do they do?
T3 receptors
Found in nucleus
Unbound receptors bind silencer elements
Liganded receptors fuction as activators
What is the biologically inactive form of T3?
rT3
