M&n Week 5: Ch. 3 Endocrine Physiology

Front 1

Which pituitary hormones are more vulnerable to mechanical damage?

Where are they located?

Back 1

1. Somatotrophs
2. Gonadotrophs

*Posterolateral region of the anterior pituitary

Front 2

Which pituitary hormones are less vulnerable to mechanical damage?

Back 2

1. Corticotrophs (anteromedial region)
2. Thyrotrophs (anteromedial region)
3. Lactotrophs (dispersed throughout)

Front 3

Nerve fibers in the posterior pituitary have cell bodies located where?

Back 3

Supraoptic and Paraventricular nuclei of the hypothalamus

Front 4

Describe the nature of the release pattern of the anterior pituitary hormones

Back 4

Cyclic in nature

Front 5

Most rhythms of anterior pituitary hormone secretion are driven by what?

Back 5

Internal biological clock located in the hypothalamic suprachiasmatic nucleus

Front 6

What factors synchronize the hypothalamus suprachiasmatic nucleus?

Back 6

External signals such as light and dark periods

Front 7

List 3 examples of hormones that depend on a 24-hour circadian clock for rhythmic release?

Back 7

1. ACTH
2. Cortisol
3. Melatonin

Front 8

List 3 examples of hormones whose rhythmic release is sleep related.

Back 8

1. Prolactin
2. GH
3. TSH

Front 9

Which hormones are released during superficial phases of sleep?

Back 9

1. TSH
2. Cortisol

Front 10

Which hormone is secreted during the first slow-wave sleep episode at the beginning of the night?

Back 10

GH

Front 11

Hormones of the anterior pituitary gland can be classified into which 3 families?

Back 11

1. Glycoproteins
2. Derivatives of POMC
3. GH and prolactin

Front 12

Which hormones are among the largest hormones known to date?

Back 12

Glycoproteins

Front 13

List 4 glycoprotein hormones.

Back 13

1. TSH
2. FSH
3. LH
4. hCG

Front 14

Describe the subunits that are common and unique to the glycoprotein hormones

Back 14

(Heterodimeric)
1. Alpha subunits = common among all glycoprotein hormones
2. Beta subunits = unique; confers specificity to each hormone

Front 15

Where exactly is TSH produced?

Back 15

Parvocellular neurons in the paraventricular nuclei of the hypothalamus.

Front 16

What kind of receptor does TRH bind to and what intracellular signaling pathway is activated?

Back 16

G-protein coupled receptor
Phospholipase C pathway is activated
(phosphorylation cascade begun by adenylate cylase and cAMP)

Front 17

What kind of receptor does TSH bind to and what intracellular signaling pathway is activated?

Back 17

G-protein coupled receptor
Protein kinase A pathway
(phosphorylation cascade begun by adenylate cyclase and cAMP)

Front 18

Which thyroid hormone is particularly active in negative feedback inhibition of TSH release?

Back 18

T3

Front 19

What kind of receptor does GnRH bind to and which intracellular signaling pathway is activated?

Back 19

G-protein coupled receptor
*Phospholipase C signaling pathway

Front 20

List the 4 target cells of gonadotropins.

Back 20

1. Ovarian granulosa cells
2. Theca interna cells
3. Testicular Sertoli cells
4. Leydig cells

Front 21

List the 4 physiologic responses produced by the gonadotropins.

Back 21

1. Steroidogenesis
2. Folliculogenesis
3. Spermatogenesis
4. Ovulation

Front 22

What is the effect of estradiol on LH and FSH?

Back 22

Enhances LH
Inhibits FSH

Front 23

Stimulation of POMC synthesis and peptide release is mediated through which receptor?

This receptor is located in which regions of the body?

Back 23

CRH-1 receptor (G-protein coupled; cAMP second messenger system)

1. Brain
2. Pituitary
3. Gonads
4. Skin

Front 24

CRH hypothalamic neurons also produce which neuropeptide?

Back 24

Vasopressin

*Also stimulates release of POMC-derived peptides from the anterior pituitary

Front 25

POMC is post-translationally cleaved to form which 3 hormones?

Back 25

1. ACTH
2. Beta-endorphin
3. a,B, and y-Melanocyte-stimulating hormones (MSHs)

Front 26

The biologic effects of POMC-derived peptides are largely mediated through which receptors?

Back 26

Melanocortin receptors (MCRs)
MC1R, MC2R, MC4R, MC5R

Front 27

Describe where the 5 MCRs act in the body.

Back 27

MC1R => skin
MC2R => adrenal steroid hormone production
MC3R => ?
MC4R => brain (feeding behavior, appetite)
MC5R => thermoregulation

Front 28

How is the release of ACTH stimulated?

Back 28

Psychological and physical stress

Front 29

Describe the releasing pattern of ACTH and what time of the day it is released in the highest concentration and lowest concentration.

Back 29

Pulsatile release

Highest --> 4:00AM
Lowest --> afternoon

Front 30

Although all 5 MCRs can bind ACTH to some extent, which one binds ACTH with the highest affinity?

Where is this receptor almost exclusively located?

Back 30

MC2R

*Adrenal cortex

Front 31

Which melanocortin receptor is considered the physiologic ACTH receptor?

Back 31

MC2R

Front 32

The release of cortisol follows the same diurnal rhythm as that of which hormone?

Back 32

ACTH

Front 33

Which melanocortin receptor is located in melanocytes?

Back 33

MC1R

Front 34

What is the most abundant endogenous opiod peptide?

Back 34

beta-endorphin

Front 35

What are some of the physiologic actions of endorphins?

Back 35

1. Analgesia
2. Behavioral effects
3. Neuromodulatory functions

Front 36

What are the functions of Pit-1?

Back 36

1. Activates transcription of the GH gene
2. Stimulates transcription of the GHRH receptor gene

*Pit-1 = pituitary-specific transcription factor. It's transcription is enhanced by GHRH.

Front 37

During which part of the day are prolactin levels the highest?

Back 37

During sleep
(lowest during the waking hours)

Front 38

What is the most important environment stimuli that activates prolactin?

Back 38

Suckling

Front 39

How is the surge in prolactin release in response to a suckling stimulus mediated?

Back 39

It is mediated by a decrease in the amount of dopamine released at the median eminence, relieving the lactotroph from tonic inhibition.

Front 40

What is the effect of estrogen on lactotrophs during pregnancy?

Back 40

Stimuluates growth of the lactotrophs as well as prolactin gene expression and release

Front 41

How does prolactin inhibit its own release?

Back 41

By stimulating dopamine release from the hypothalamus

Front 42

List 4 neuropeptides that have been identified as prolactin-releasing factors.

Back 42

1. TRH
2. Oxytocin
3. Vasoactive intestinal peptide (VIP)
4. Neurotensin

Front 43

T or F

Even in the presence of dopamine, TRH is a potent stimulus for the release of prolactin

Back 43

TRUE

Front 44

List 3 locations of prolactin receptors in the body.

Back 44

1. Ovary
2. Mammary gland
3. Brain

Front 45

What are the main physiologic effects of prolactin?

Back 45

1. Stimulation of growth and development of the mammary gland
2. Synthesis of milk
3. Maintenance of milk secretion

Front 46

How does prolactin stimulate the synthesis of milk?

Back 46

Stimulates glucose and amino acid uptake ---> synthesis of
1. milk proteins (beta-casein, alpha-lactalbumin)
2. milk sugar (lactose)
3. Milk fats

Front 47

How is the production of milk prevented during pregnancy?

Back 47

High progesterone levels

Front 48

Besides mammary development and milk synthesis, what are some other effects of prolactin?

Back 48

1. Inhibition of GnRH release
2. Progesterone biosynthesis
3. Luteal cell hypertrophy during pregnancy
4. Reproductive and parental behavior
5. Modulates immune cell function

Front 49

What is the most common cause of excess production of pituitary hormones?

Back 49

Hormone-producing pituitary tumor
(Prolactinomas most common)

Front 50

What is the most frequent cause of pituitary insufficiency?

Back 50

Trauma
(surgery, penetrating injury, car accidents)

Front 51

Which hormonal deficiency is most common in hypopituitarism?

Back 51

Isolated GH or gonadotropin deficiencies

Front 52

Ischemic damage to the pituitary gland or hypothalamic-pituitary stalk during the peripartum period leads to what condition?

Back 52

Sheehan's syndrome

Front 53

Which syndrome is characterized by deletions or mutations in the GH receptor gene, resulting in failure to generate IGF-1 and IGFBP-3?

Back 53

Laron syndrome
(GH insensitivity)