Endocrine - Hormones I

Question 1

What is optimal pH for most human hormones? Temp?

Answer 1

pH - 7.35-7.45

Temp - 37 C

Question 2

What is the master of the endocrine system that connects neural inputs to hormonal outputs?

Answer 2

Hypothalmus

Question 3

What secretes tropic hormones?

Answer 3

Pituitary

Question 4

What is endocrine? Paracrine? Autocrine?

Answer 4

Endocrine - sent through blood stream to have distant effect
Paracrine - works on adjacent cells
Autocrine - works on cells in which it was synthesized

Question 5

Do organs or tissues without receptors for specific hormones respond to stimulating effects from hormones?

Answer 5

No

Question 6

What hormone is a tripeptide?

Answer 6

TRH

Question 7

What hormones are derived from cholesterol? (5)

Answer 7

Mineralcorticoids
Glucocorticoids
Androgens
Estrogens
Vit D

Question 8

Where are receptors for protein hormones? Steroid hormones? Why?

Answer 8

Protein hormones - hydrophillic - receptor on membrane of target cell
Steroid hormones - hydrophobic - receptors located inside cell

Question 9

What is it called when binding of a hormone to a specific receptor causes a cascade of reactions?

Answer 9

Signal transduction

Question 10

What receptor type does insulin utilize? How?

Answer 10

Tyrosine kinase receptor
Autophosphorylation of Y residues intracellularly
This catalyzes phosphorylation of IRS 1-4
Stimulate kinases

Question 11

What 4 hormones follow the Jak-Stat pathway?

Answer 11

GH, Prolactin, erythropoiten, cytokines

Question 12

In the JAK-STAT pathway, what happens after a ligand binds?

Answer 12

Receptors dimerize
Intracellular JAKs autophosphorylize
The phosphorylate intracellular Y domains of receptor
STATs then phosphorlyze
2nd dimerization of STATs causes nuclear translocation

Question 13

Describe the G-protein-coupled receptor pathway??

Answer 13

Receptor has alpha, beta, and gamma bound intracellularly Hormone binds to receptor, displacing GDP bound to alpha subunit by GTP
The subunit abgamma is displaced from receptor (alpha and betagamma) Intermediates are produced by alpha subunit binding to another receptor
Alpha uses intrinsic GTPase property to convert GTP back to GDP
All subunits reassemble with original receptor

Question 14

What are 5 common 2nd messengers of GPCR?

Answer 14

cAMP
cGMP
Ca+2
DAG
Phosphatidylinositides

Question 15

How does cAMP work inside a cell?

Answer 15

Binds to R2C2 and displaces R2 (regulator subunit) Catalytic subunit now free, so PKA is active
Phosphorylation of proteins can occur

Question 16

What are the two forms of gunaylyl cyclase? What stimulates each? What is activated? What does this do?

Answer 16

Membrane bound - stimulated by hormone
Soluble - stimulated by NO
Activates PKG
Phosphorylates SM proteins cause SM relaxation and vasodilation

Question 17

How is Gq receptor tied into Ca, IP3, and DAG?

Answer 17

Hormone binds Gq
alpha subunit stimulates Phosphlipase C
This cleaves PIP2 into DAG and IP3
IP3 interacts with receptor on ER causing increase Ca concentration
This increases protein phosphorylation

Question 18

What are the two types of receptors for lipophilic hormones? Name examples of each

Answer 18

Cytosolic (subclass I) - sex steroids
Nuclear (Subclass-II) - thyroid hormone, Vit. A, Vit D

Question 19

What are home secretions usually tightly regulated by?

Answer 19

Negative feedback system