Hypothalamic Pituitary Relationships and Biofeedback Pt. 1

Question 1

Describe the parts and structure of the pituitary gland

Answer 1

Anterior (epithelial/adenohypophysis)
Posterior (neural/neurohypophysis)
Hypophyseal stalk connects it to hypothalamus

Question 2

What is the first structure affected by a pituitary tumor? Why?

Answer 2

Vision as it puts pressure on the optic nerves

Question 3

What are the features of the posterior pituitary?

Answer 3

Neural. Axons extending into the gland and releases hormones (ADH and oxytocin)

Question 4

What nuclei control the posterior pituitary?

Answer 4

SON (supraoptic) and PVN (paraventricular)

Question 5

What are the features of the anterior pituitary?

Answer 5

• Neural and hormonal connections (connected to hypothalamus via the hypothalamic-hypophyseal blood vessels)
• release FLAT PG

Question 6

Describe how the anterior pituitary communicate via hypothalamic-hypophyseal portal system

Answer 6

Hormones are released in high concentrations to tropic cells in AP > AP releases hormones in circulation
-Rapid response = prevents buildup of hormones in the circulation

Question 7

3 families of hormones of the AP
Corticotrophs
Gonadotrophs
Somatotrophs/lactotrophs

Answer 7

• ACTH (stimulated by CRH)
• TSH/FSH/LH (stimulated by GnRH)
• GH/Pro (stimulated by GHRH, TRH)

Question 8

Which hormones have inhibitory mechanisms of action?

Answer 8

GHIH (somatostatin) - prevents GH release by somatotrophs

PIF (dopamine) - prevents prolactin release by lactotrophs

Question 9

What does primary, secondary and tertiary disorder mean?

Answer 9

Primary - problem level of the peripheral gland
Secondary - problem level of the pituitary gland
Tertiary - problem level of the hypothalamus

Question 10

Draw the HPG (hypothalamus-pituitary-gonad axis)

Answer 10

Ok

Question 11

Regulation and action of the FSH and LH hormones

Answer 11

Regulated by the pulsatile release of GnRH (fueled by enough body energy). They promote spermatogenesis and estrogen/progesterone/testosterone release

Question 12

Acromegaly
Cause
Clinical

Answer 12

• Increased exposure to growth hormone due to pituitary adenoma after puberty after the epiphyseal plates have closed
• growth of extra bone/soft tissue/cartilage growth

Question 13

Draw the growth hormone axis

Answer 13

Ok

Question 14

What type of signaling does the GH receptor use?

Answer 14

JAK-STAT

Question 15

At what physiological state is the growth hormone usually secreted?

Answer 15

Times of hunger/hypoglycemia

Question 16

What are the actions of GH as it binds directly to MSK?

Answer 16

Hypertrophy of cells
Hyperplasia (make more cells)
Increase metabolism

Question 17

How does GH indirectly cause growth?

Answer 17

Stimulates the liver to produce IGF-1 which encourages growth of everythingmajority of its effects are done indirectly

Question 18

What happens if there is insensitivity of receptors to growth hormone (primary)?

Answer 18

-High GH in circulation and low IGF-1 production in liver

Question 19

What happens when there is secondary (pituitary level deficiency?)
How would you treat this?

Answer 19

Pituitary isn't making the GH and liver isn't making IGF-1. High GHRH
GH replacement (Somatropin, Somatrem, Mecasermin)

Question 20

What happens in tertiary (hypothalamic level) deficiency?

How would you treat this?

Answer 20

No release of GHRH from the hypothalamus. Low everything.

Semorelin

Question 21

Gigantism
Cause
Clinical

Answer 21

Exposure to excess GH due to pituitary adenoma before epiphyseal plates close (before puberty)
-giant

Question 22

How is the HPG axis working during the fed state (favrable)

Answer 22

Adequate insulin and amino acid availability. Liver produces IGF-1 > trigger growth processes

Question 23

How is the HPG axis altered in unbalanced fed state (high carbs low protein)

Answer 23

High insulin but low AA availability. Can’t make GH, can’t make IGF-1

Question 24

How is HPG axis altered in unbalanced fed state (low carbs high protein)?

Answer 24

IGF-1 produced and triggers growth. Inadequate sugar = use fat as energy and result in lipolysis.
Since sugar is low - stimulate gluconeogenesis and increase blood sugar levels

Question 25

How do you diagnoses someone with excess GH (gigantism/acromegaly?

Answer 25

Serum has elevated GH and IGF-1 and fail the oral glucose test (no decrease of GH after oral glucose)
Also pituitary enlargement (adenoma)

Question 26

Describe the fluctuation of GH secretion throughout the day

Answer 26

Spike during sleep. During waking hours highest while exercising.

Question 27

What causes stimulation of prolactin secretion?

Answer 27

Pregnancy (via estrogen)
Breast feeding (suckling)
Sleep 
Stress
TRH

Question 28

What are pituitary adenomas?

Answer 28

Adenomas release extra hormone and release into bloodstream

Result in hyperpituitarism (prolactinoma)

Question 29

What does the posterior pituitary release?

Answer 29

Oxytocin and ADH (neuropeptides)

Question 30

In the posterior pituitary, what nuclei controls ADH and Oxytocin?

Answer 30

ADH = supraoptic nuclei
Oxytocin = paraventricular nuclei

Question 31

Draw the oxytocin axis

Answer 31

Ok

Question 32

How does Oxytocin stimulate milk ejection?

Answer 32

Contracts the myoepithelial cells lining milk ducts (stimulated by suckling mostly)

Question 33

How does oxytocin stimulate uterine contraction?

Answer 33

Dilation stimulates oxytocin release which stimulates contractions and further dilations. Pitocin induces labor.