Endo: Hypoth Control of Pit

Question 1

Name the origin of anterior and posterior pituitary

Answer 1

• Anterior = oral ectoderm (Rathke’s pouch)
• Posterior = neuroectoderm

Question 2

Compare the role of neurons in anterior v posterior pituitary

Answer 2

• Posterior: hypothalamus neurons release ADH and oxytocin directly into posterior pituitary
• Anterior: hypothalamus neurons in median eminence release releasing factors into hypothalamo-hypophyseal portal system

Question 3

Hormones released by the hypothalamus are predominantly ______ hormones

Answer 3

Hormones released by the hypothalamus are predominantly peptide hormones

Question 4

What hormones are released by hypothalamus into the portal system? (6)

Answer 4

• GnRH (stimulates FSH, LH)
• CRH (stimulates ACTH)
• TRH (stimulates TSH and PRL)
• DA (inhibits TSH and PRL)
• GHRH (stimulates GH)
• Somatostatin (inhibits GH and TSH)

*PRL also suppresses GnRH release

Question 5

Name the cells that produce each type of anterior pituitary hormone

Answer 5

Within the anterior pituitary,

• Gonadotrophs make FSH, LH
• Corticotrophs make ACTH
• Thyrotrophs make TSH
• Lactotrophs make PRL
• Somatotrophs make GH

Question 6

All hormones released by anterior pituitary are _______ hormones

Answer 6

All hormones released by anterior pituitary are protein hormones

Question 7

How does prolactin cause a change in the target cell? (cell signaling)

Answer 7

• Prolactin binds to a cytokine receptor, which activates JAK/STAT pathway
• Jack and the beanstalk and his PIGGLET
  
  • PRL, Interleukins, GH, G-CSF, EPO, TPO all use non-receptor tyrosine kinases

Question 8

Describe the action of prolactin (3)

Answer 8

• Prolactin stimulates mammary gland development and milk production
• Prolactin inhibits GnRH release

Question 9

What inhibits and what stimulates prolactin release?

Which is the predominant control?

Answer 9

• Prolactin release is inhibited by dopamine from tuberoinfundibular pathway
• Prolactin release is stimulated by TRH
• INHIBITION is predominant

Question 10

Why does haloperidol cause hyperprolactinemia?

Answer 10

• Haloperidol blocks D2 receptors
• Dopamine normally inhibits Prolactin release
• Without D2 activation, get increased prolactin release

Question 11

Symptoms of hyperprolactinemia (3)

Why does each occur?

Answer 11

• Galactorrhea (milk production)
  
  • Direct effect of increased prolactin
• Amenorrhea
  
  • Excess prolactin inhibits GnRH production in hypothalamus (negative feedback)
• Decreased libido

Question 12

What is Sheehan’s Syndrome?

Answer 12

Loss of pituitary function after child birth due to hemorrhage

First symptom is failure to lactate

Question 13

Which hormones use receptor tyrosine kinases?

Answer 13

• Insulin
• Growth factors (IGF-1, FGF, PDGF, EGF)

Question 14

What hormones use IP3/DAG signaling? (Gq)

Answer 14

Gnome GOATs are Qute!

• GnRH
• Oxytocin
• ADH (V1)
• TRH

Also,

• Gastrin
• Angiotensin II
• Histamine (H1)

Question 15

What type of receptor is used by the hypothalamic hormones? (5)

Answer 15

• GnRH uses Gq
• CRH uses Gs
• TRH uses Gq
• GHRH uses Gs
• SST uses Gi