General Endocrine

Question 1

What are the functions of the endocrine system?

Answer 1

regulate: energy breakdown and storage, reproduction sexual and gamete development and behavior, growth-proliferation, differentiation, and skeletal, and internal milieu- composition of body fluids, electrolytes, acid-base, and glucose

Question 2

What are the multifactorial aspects of regulation in the endocrine system?

Answer 2

a hormone can regulate multiple functions and each function can be controlled by several hormones

Question 3

What are the four major classes of hormone precursor molecules?

Answer 3

protein, cholesterol, AA and FA

Question 4

What can protein precursors become when deriving hormones? examples of each.

Answer 4

protein- GH, FSH, LH (LH and FSH are 2 polypeptides); Cleave or processed peptide- ACTH, ADH, PTH, and oxytocin; AA cleavage for thyroid hormones T3 and T4

Question 5

What can AA precursors become when deriving hormones? examples of each.

Answer 5

tripeptide-TRH and modified AA- NE and Epi

Question 6

What can Cholesterol precursors become when deriving hormones? examples.

Answer 6

steroid- cortisol, androgens, and estrogens

Question 7

What can FA precursors become when deriving hormones? examples

Answer 7

retinoids, Vit D3, Eicosanoids - 1-25OH Vit D3 and Prostagandins

Question 8

What is a endocrine gland?

Answer 8

conglomeration of source cells that produce a specific hormone

Question 9

How are hormones effects limited to target cells?

Answer 9

target cells respond because they have the receptor for the hormone, cells without the receptor are unaffected directly, hormone must come in direct physical contact with target cell receptor

Question 10

Where are receptors located for hormones?

Answer 10

polypeptide hormone receptors on cell surface; steroid hormone receptors either cytoplasm or in nucleus

Question 11

How are hormones transported?

Answer 11

through the blood; steroids are bound to a protein

Question 12

What are the salient features of hormones and their target cells?

Answer 12

binding is saturable and reversible, use second messengers, response elicited determined by target cell and not type of second messenger, can only slow or speed up an existing process not create a new process, rarely process sensitive to only one hormone, hormones usually have multiple actions in multiple sites

Question 13

Why have input from multiple hormones?

Answer 13

redundancy of function, safety net, ensures maintenance of internal environment under diverse conditions (homeostasis)

Question 14

The same precursor can be used for different hormones. How is this achieved?

Answer 14

the enzymes in the different glands break the precursor molecule up differently

Question 15

What is the function of hormone binding globulins?

Answer 15

bind while circulating in plasma; increase half life and assure uninterrupted delivery, no function while bound free hormone (active form) binds to receptor and is in equilibrium with hormones bound to globulins so they are released upon demand; synthesized mostly in the liver

Question 16

What happens to a hormone after binding to a receptor and eliciting response?

Answer 16

action terminated, metabolized to give additional precusors to produce more hormones for local or systemic actions, selectively degraded to prevent local action or metabolized to inactive forms that are eliminated

Question 17

In breakdown of hormones, what is the difference between peptide and steroid?

Answer 17

peptide- bind to receptor, endocytosed and degraded in a lysosome; steroid- metabolized to inactive analogs or converted to water soluble forms for secretion

Question 18

What is the difference between steroids/thyroids and peptides and catecholamines in storage capability?

Answer 18

S/T-minimal except thyroids; P/C-Yes

Question 19

What is the difference between steroids/thyroids and peptides and catecholamines in binding proteins?

Answer 19

S/T- always; P/C- uncommon

Question 20

What is the difference between steroids/thyroids and peptides and catecholamines in half life?

Answer 20

S/T- Long hours to days; P/C- short minutes

Question 21

What is the difference between steroids/thyroids and peptides and catecholamines in action mechanism?

Answer 21

S/T- direct, no second messenger, transcriptional; P/C- indirect, second messengers, transcriptional and translational

Question 22

What are the classes of polypeptide receptors?

Answer 22

GPCR and enzyme-linked (dimerization; activates intrinsic kinase or recruits and activates associated kinase)

Question 23

What is the function of the alpha subunit in Gs? Gi? Gq?

Answer 23

Gs- activates andenylate cyclase; Gi- inhibits cyclase, Gq- activates phospholipase Cbeta

Question 24

After being activated by alpha subunit of the Gq GPCR what does phospholipase C do?

Answer 24

cleave PIP2 to DAG and IP3; then DAG and Ca activate PKCwhich is recruited to plasma membrane

Question 25

What do GKR and arrestin do?

Answer 25

GRK phosphorylates only activated GPCR because it is activated by GPCR; arrestin binds to phosphorylated GPCR and prevents its binding to G protein and induces endocytosis

Question 26

What are the three distinct domains of polypeptide intracellular receptors? function?

Answer 26

AF-1 (activation function) domain at amino terminus and AF2 at carboxy terminus which activate transcription; DBD (DNA binding domain) bind specific DNA motifs; LBD (ligand binding domain) binds the hormone, CoA and CoR- coactivators and suppressors that modify transcription rate

Question 27

What are two important domains in intracellular receptors other than the distinct domains?

Answer 27

NLS- nuclear localization sequence, targets protein to the nucleus; DMD- dimerization domain, links two receptors together for DNA binding

Question 28

What are the differences between heterodimeric and homodimeric intracellular receptors?

Answer 28

homo- binds hormone in the cytoplasm, idle receptor kept in inactive state by inhibitors bound to hormone binding site which are dissociated by the hormone, use NLS to translocate to nucleus; hetero- are in the nucleus, not understood how they are kept idle

Question 29

What are examples of homodimeric receptors?

Answer 29

estrogen, progesterone, androgen, glucocorticoid, and mineralocorticoid

Question 30

What are examples of heterodimeric receptors?

Answer 30

thyroid, retinoic acid and Vitamin D

Question 31

In the example of estrogen receptors how does the co-repressor keep it in an inactivated state?

Answer 31

CoR recruits HDAC (histone deacetylases) which maintain histones in a deacetylated state which favors chromatin condensation

Question 32

How does estrogen binding cause activation of the receptor and transcription?

Answer 32

results in a conformational change in AF2 that facilitates interaction with CoA which bind HAT (histone acetyltranferase); acetylation of histones leads to chromatin decondensation facilitating transcriptional activation; AF1 and AF2 activate transcription independently or synergistically

Question 33

What are three ways or places affected that cause hormone resistance can occur?

Answer 33

abnormal hormone, receptor defect, post receptor mechanism

Question 34

What hormones receptors are known to have genetic defects that destroy either receptor specificity or receptor binding?

Answer 34

glucocorticoids, T3 and T4, DHT, Vitamin D3, ADH, GH and TSH

Question 35

What are the different places/mechanisms that can cause hypofunction of a hormone?

Answer 35

destruction or block at the gland, block from prohormone to hormone, stimulation of degradation process (decreasing 1/2 life), antibodies and antagonists affecting receptors, defect in receptor, effector system or response, or tissue damage effecting the response

Question 36

What are the different places/mechanisms that can cause hyperfunction of a hormone?

Answer 36

tumor or hyperplasia at the gland, ectopic production or Iatrogenic of prohormone or hormone, block of degradation (increasing half life), antibodies/agonists stimulating receptors, stimulation of receptor, effector or response element, and tissue damage like precursor of response in excess

Question 37

What are examples of conditions of caused by hypofunction due to destruction of endocrine glands?

Answer 37

autoimmune disease; type I diabetes, hypothyroidism, adrenal insufficiency, gonadal failure

Question 38

What are examples of conditions of caused by hypofunction due to extra-glandular disorders?

Answer 38

effecting absorption and metabolism of hormone; defective conversion of 25D3 to 1,25 D3; deficiency of 5alpha-reductase resulting in impaired DHT from T

Question 39

What are examples of conditions of caused by hypofunction due to specific defects in hormone biosynthesis and transport?

Answer 39

21-hydroxylase deficiency syndrome causing defective cortisol production, dietary iodine deficiency results in deficient thyroid hormone biosynhtesis

Question 40

What are examples of conditions of caused by hyperfunction due to endocrine tumors?

Answer 40

pituitary causing overproduction of ACTH, GH, PRL, TSH, LF, FSH

Question 41

What are examples of conditions of caused by hyperfunction due to ectopic tumor?

Answer 41

tumors produce hormones (ACTH, ADH and calcitonin)

Question 42

What are examples of conditions of caused by hyperfunction due to anti-receptor antibodies?

Answer 42

autoimmune stimulation results in production of antibodies that stimulate TSH receptor causing hyperthyroidism

Question 43

What is TRH?

Answer 43

thyrotopin releasing hormone

Question 44

What is CRH?

Answer 44

corticotropin releasing hormone

Question 45

What is GHRH?

Answer 45

growth hormone releasing hormone

Question 46

What is GnRH?

Answer 46

gonadotropin releasing hormone

Question 47

What is SS?

Answer 47

somatostatin

Question 48

What is TSH?

Answer 48

thyroid stimulating hormone

Question 49

What is ACTH?

Answer 49

adrenocorticotropic hormone

Question 50

What is PRL?

Answer 50

Prolactin

Question 51

What is GH?

Answer 51

growth hormone

Question 52

What is FSH?

Answer 52

follicle stimulating hormone

Question 53

What is LH?

Answer 53

luteininzing hormone

Question 54

What is DHT

Answer 54

dihydro-testosterone

Question 55

What is ER?

Answer 55

estrogen

Question 56

What is T?

Answer 56

testosterone

Question 57

What is T3 and T4?

Answer 57

thyroid hormones

Question 58

What types of control are endocrine glands under?

Answer 58

most neuroendocrine, some metabolic (by metabolite)

Question 59

What effect does CNS play with endocrine system?

Answer 59

endocrine can affect CNS (mood, anxiety, or behavior); CNS controls release of master hormones (releasing hormones) from hypothalamus these can be stimulatory or inhibitory

Question 60

What do releasing hormones do?

Answer 60

stimulate or inhibit the secretion of tropic hormones from the pituitary which cause the release of organ/target hormones or ultimate hormones

Question 61

What do target hormones do?

Answer 61

act on target cells throughout the body; exert feedback control on hypothalamus and pituitary (usually negative) or metabolite from target cells feeds back on the gland itself