Hypothalamic and Pituitary relations part 1 Flashcards
What connects the hypothalamus to the pituitary gland?
Hypophysial stalk (infundibulum)
What type of connection does the hypothalamus have to the posterior pituitary gland?
Neural signal
What type of connection does the hypothalamus have to the anterior pituitary gland?
Neural and hormonal (endocrine) signals
Another name for the pituitary gland
Hypophysis
What are the initial signs of a pituitary gland tumor?
Dizziness and visual problems because it compresses the optic nerves
What are the nuclei in the hypothalamus that send axons to the posterior pituitary?
Supraoptic and paraventricular nuclei
What do the supraoptic and paraventricular nuclei in the hypothalamus send down their axons to the posterior pituitary for it to release?
ADH and Oxytocin
What do the hypothalamic neurons use to send releasing-hormones or release-inhibiting hormones to the anterior pituitary?
Hypothalamic-hypophysial portal vessels (blood)
Once the releasing hormones or release-inhibiting hormones reach the anterior pituitary, what do they do?
They either stimulate or inhibit the release of anterior pituitary hormones
Corticotrophs
ACTH
Thyrotrophs
TSH
Gonadotrophs
FSH and LH
Somatotrophs
GH
Lactotrophs
Prolactin
Primary endocrine disorders affect?
Peripheral gland
Secondary endocrine disorders affect?
Pituitary gland
Tertiary endocrine disorders affect?
Hypothalamus
HPG axis
Hypothalamic-pituitary-Gonadal axis
What does the hypothalamus release to the anterior pituitary for the HPG axis?
GnRH
What does the anterior pituitary release to the testes for the HPG axis?
LH and FSH
For the HPG axis for Testes, LH stimulates _____ to release _____
Leydig cells to release Testosterone
For the HPG axis for Testes, FSH stimulates ______ to perform _________
Sertoli cells to perform spermatogenesis
What can sertoli cells produce to inhibit FSH release from the anterior pituitary?
Inhibin
Testosterone has a negative feedback loop at what locations?
Anterior pituitary (LH) and Hypothalamus (GnRH)
For the HPG axis for Ovaries, LH stimulates ____ to release _____
Theca cells to release Androgens
For the HPG axis for Ovaries, FSH stimulates ______ to release ______
Granulosa cells to release progestins and estrogens
What can granulosa cells produce to inhibit FSH release from the anterior pituitary?
Inhibin
For the negative feedback pathway in the Ovaries, what can have a negative feedback loop at what locations?
Progestins and Estrogens can have a negative feedback loop at the Anterior pituitary and at the Hypothalamus levels
Leydig cells and Theca cells activate or release androgens that do what?
Stimulate the roles of the Sertoli cells and the Granulosa cells
For the GH axis, what does the Hypothalamus release?
Either GHRH (growth hormone releasing hormone) OR GHIH (growth hormone inhibiting hormone)
Once the hypothalamus releases GHRH to the anterior pituitary it releases GH to where?
Either directly to the bones and soft tissue or to the liver
What does the liver release in response to GH?
IGF-1
What does IGF-1 do?
Stimulates growth of bone and soft tissue
What types of feedback does IGF-1 contain?
(+) stimulates GHIH which then inhibits GH release
(-) inhibits GH release directly at anterior pituitary
GH has negative feedback where?
At the hypothalamus to inhibit GHRH
GH secretion fluctuates throughout the day, when is it at its highest?
During sleep and during exercise
GH secretion fluctuates throughout a lifetime, describe it.
GH secretion increases until it reaches a peak during puberty and then slowly declines with old age
What can excessive GH lead to?
Gigantism or acromegaly
Excessive GH BEFORE closure of bone epiphyses
Gigantism
Excessive GH AFTER closure of bone epiphyses
Acromegaly
What is acromegaly?
Excessive growth of soft tissue - large hand, large feet, large head – cartilagenous tissues
INCREASED GH released from anterior pituitary due to decreased or lost IGF-1 feedback
Primary GH deficiency because it affects the liver
DECREASED GH released from anterior pituitary
Secondary GH deficiency
DECREASED GHRH released from hypothalamus
Tertiary GH deficiency
Increased carb intake and increased protein intake does what to the GH axis?
Liver produces IGF-1 for growth
Increased carb intake and decreased protein intake does what to the GH axis?
Inhibits GH and Liver will NOT produce IGF-1 and this results in weight gain
Decreased carb intake and increased protein intake does what to the GH axis?
Produces lots of GH and promotes lipolysis yet, insulin insensitivity
When the hypothalamus releases dopamine to the anterior pituitary what does it do?
It inhibits the anterior pituitary and allows release of Prolactin
Prolactin is increased with pregnancy and can negatively inhibit what?
GnRH in order to stop menstrual cycles
How is oxytocin packaged?
Prepro-oxyphysin is put into vesicles as pro-oxyphysin in the hypothalamus and is then sent to the posterior pituitary to be released as Oxytocin
What are the main actions of oxytocin?
Milk letdown for breast feeding and Uterine contraction during childbirth