Hypothalamic-Pituitary relationships

Question 1

where do cancers of pituitary expand?

Answer 1

into the brain & against the optic nerves
– increase in pituitary size often associated with dizziness &
vision problems, or both

Question 2

what neuropeptide does SON secrete?

Answer 2

ADH

Question 3

what neuropeptide does PVN secrete?

Answer 3

oxytocin

Question 4

what hormones does ant. pituitary secrete?

Answer 4

– ACTH
– TSH
– FSH
– LH
– GH
– Prolactin

Question 5

how is the ant pituitary connected to hypothalamus?

Answer 5

• Connected to the hypothalamus
by hypothalamic-hypophysial
portal vessels

Question 6

what does thehypothalamic-hypophysial

portal vessels allows?

Answer 6

– Hypothalamic hormones
can be delivered to the
anterior pituitary
directly & in high
concentration
– The hypothalamic
hormones do not appear
in the systemic
circulation in high
concentration`

Question 7

1 endocrine disorder:

Answer 7

low or high levels of
hormone due to defect in the peripheral endocrine
gland

Question 8

2 endocrine disorder:

Answer 8

low or high levels of

hormone due to defect in the pituitary gland

Question 9

3 endocrine disorder:

Answer 9

low or high levels of

hormone due to defect in the hypothalamus

Question 10

Acromegaly

Answer 10

Caused by prolonged,
excessive secretion of
growth hormone (GH) in
adult life

• Characterized by excessive
growth of soft tissue,
cartilage, & bone in the
face, hands, & feet
• Develops very gradually;
may not be recognized until
it has been present for
many years

Question 11

how do you diagnose acromegaly?

Answer 11

measure IGF-1

• levels constant throughout day
• should show increase IGF-1 and failure to suppress GH following oral glucose tolerance test

Question 12

what are medications for acromegaly?

Answer 12

– Octreotide or lanreotide: Somatostatin analog
– Pegvisomant: GH receptor antagonist
– Bromocriptine or cabergoline: Dopamine receptor
agonists

Question 13

in what manner is GH released?

Answer 13

secreted from

somatotrophs in a pulsatile manner

Question 14

what are effects of GH

Answer 14

1) increase blood gluocse
(increases blood insulin)
2) increase protein syntheiss and organ growth (mediated by somatomedins)
3) increase linear growth (increase chondrocytes proliferation)
(mediated by somatomedins)

Question 15

what does prolactin inhibit?

Answer 15

GnRH-> FSH and LH

Question 16

what inhbits prolactin?

Answer 16

dopamine

Question 17

what does somatostatin inhibit?

Answer 17

GH

Question 18

what does TRH increase?

Answer 18

TSH and prolactin

Question 19

what are non functioning pituitary adenomas associated with?

Answer 19

FSH and LH

Question 20

causes of hypopituitarism

Answer 20

1) brain damage
2) pituitary tumors
3)non-pitutiary tumors
4)infections
5) infarction (sheehan syndrome)
– Autoimmune disorders
– Pituitary hypoplasia or aplasia
– Genetic causes

Question 21

Sheehan syndrome

Answer 21

Postpartum
hypopituitarism due to
necrosis of the pituitary
gland
• Most patients present
with agalactorrhea &/or
difficulties in lactation
• Amenorrhea commonly
presented
• Some patients present
with hypothyroidism

Question 22

posterior lobe hormones

Answer 22

– ADH & oxytocin

Question 23

what triggers ADH secretion?

Answer 23

1) decrease BP
2) decrease arterial stretch due to low blood volume
3) increase osmolarity

Question 24

actions of ADH

Answer 24

1) V1 blood vessel receptors to vasoconstrict
2) V2 kidney receptors to reabsorb H20

overall goal= increase blood pressure and volume

Question 25

what is secretion of ADH most sensitive to

Answer 25

plasma osmolarity | changes!

Question 26

how does ADH increase H20- reabsorption

Answer 26

-V2 receptor= Gprotein increase adenylate cyclase and camp -aquoporin 2 channels inserted in membrane

Question 27

Diabetes insipidus (DI)

Answer 27

* Lack of an effect of ADH on the renal collecting duct * Causes frequent urination * The large volume of urine is diluted

Question 28

Central DI

Answer 28

``` • Lack of ADH (ê plasma ADH) • Could result from: - Damage to the pituitary - Destruction of the hypothalamus ```

Question 29

treatment for central DI

Answer 29

• Treatment: desmopressin (drug | that prevents water excretion)

Question 30

Nephrogenic DI

Answer 30

``` • Kidneys unable to respond to ADH (é plasma ADH) • Causes: - Drugs like lithium - Chronic disorders (e.g. polycystic kidney disease, sickle cell anemia) ```

Question 31

what type of DI responds to desmopressin

Answer 31

central DI

Question 32

Syndrome of inappropriate ADH secretion (SIADH)

Answer 32

* Excessive secretion of ADH * Excessive water retention * Hypoosmolarity fails to inhibit ADH release