Principles of Endocrinology

Question 1

What is the principle role of the endocrine system?

Answer 1

Maintenance of the constant internal environment despite changes in the external or internal environment (homeostasis)

Question 2

What are the three families of hormones based on their structure?

Answer 2

Peptide/ proteins; Steroids; and Amino Acid-derived

Question 3

What hormones have the longest half-lives?

Answer 3

T3 and T4

Question 4

Which hormones circulate bound to a protein?

Answer 4

Steroid and Thyroid hormones

Question 5

What is the first synthesized version of a hormone? Where is it converted to a prohormone?

Answer 5

Preprohormone is converted to prohormone in the endoplasmic reticulum

Question 6

What event mediates the fusion of secretory vesicles with the plasma membrane and release of hormones?

Answer 6

Calcium influx

Question 7

What are the different types of hormone signaling based on the site of action?

Answer 7

Endocrine- hormone enters circulation and targets an organ; paracrine- hormone acts on a nearby cell; autocrine- hormone acts on the same cell that released it

Question 8

How does a binding protein affect the half life of a hormone?

Answer 8

The proteins protect the hormone from rapid breakdown in the circulation and thus extend the half-life

Question 9

How can hormones be degraded?

Answer 9

Hormones can be internalized and degraded by the cell, processed by the liver and excreted through the bile, or excreted through urine

Question 10

What is the specificity and affinity of hormone receptors relative to other receptor types?

Answer 10

High affinity and specificity

Question 11

What is the effect of binding to a GPCR with an alpha i subunit?

Answer 11

Decreased adenylyl cyclase activity–> decreased cAMP levels

Question 12

What is the effect of binding to a GPCR with an alpha q subunit?

Answer 12

Increased phospholipase C- beta activity–> increased cleavage of PIP2 to DAG and IP3–> increased calcium–> increased phospholipase C

Question 13

What is the effect of binding to a GPCR with an alpha s subunit?

Answer 13

Increased adenylyl cyclase activity, increased cAMP

Question 14

Which hormones bind to receptor protein tyrosine kinases?

Answer 14

Insulin, GH, IGF-1

Question 15

What are the types of intracellular receptors? What structural category of hormones most typically binds to these receptors?

Answer 15

Cytosolic or nuclear; Steroid hormones

Question 16

Between membrane- and intracellular- hormone receptors, which result is elicited quicker?

Answer 16

Membrane receptors

Question 17

What are the different controls of hormone release?

Answer 17

Neural, hormonal and substrate

Question 18

From what samples can hormone measurements be taken from?

Answer 18

Tissues, Plasma, Urine, Saliva

Question 19

What is the maximal response of a hormone?

Answer 19

The effect produced by saturating does of a hormone

Question 20

How can the sensitivity to a hormone be assessed? What factors can affect this?

Answer 20

Analyzing the concentration of hormone at which there is a 50% response; The number of hormone receptors and the presence/absence of competitive or antagonistic compounds