Neuroendocrine/Pituitary Flashcards
What are the 2 hormones secreted by the posterior pituitary?
Vasopressin
Oxytocin
Where are vasopressin and oxytocin synthesized?
Magnocellular neurons in the supraoptic and paraventricular nuclei.
What does Vasopressin do?
Increases water resorption and vasoconstriction
What stimulates the release of vasopressin from the posterior pituitary?
- increased blood osmolality
- hypovolemia- low BV
- Hypotension- low BP
What is the role of oxytocin?
Milk ejection
Uterine contraction
What stimulates oxytocin?
Nursing
Uterine stimulation (stretching)
Compared to posterior pituitary, what does the anterior pituitary do?
It secretes FAMILIES of hormones as opposed to just vasopressin and oxytocin.
What are the two somatomammotropins?
GH
Prolactin
What is GH stimulated by and what does it do?
- STRESS
- Exercise
- Sleep (80% released during slow wave sleep)
Growth
Metabolism of proteins, carbs and fat
What is prolactin (PRL) stimulated by and what does it do?
- Stress
- Suckling
Lactation
Development of mamillary tissue
**It is inhibited by DA until miik is needed
What are the three glycoproteins and what do they do?
- TSH- stimulated by a decrease in temperature, leads to release of TSH which increases metabolism and therefore heat!
- FSH- regulated by GnRH (hypothalamic peptide), effects spermatogenesis and ovarian follicle development
- LH- regulated by GnRh, required for spermatogenesis, stimulates testosterone, initiates ovulation and stimulates progesterone
What are the two (3) Opiomelanocortin peptides and how is POMC related?
POMC is hte common preursor.
- ACTH: stimulated by stress > stimulates adrenal cortex to release steroids (cortisol)
- B-ED: stimulated by stress > analgesic effect (acts on u opiod receptor)
melanocortin is also made form POMC and decreases food intake/controls appetite.
What test can be done to assess pituitary function?
STRESS test
Give insulin to lower blood glucose. This leads to insulin induced hypoglycemia. You should see an increase in GH, PRL, ACTH and B-ED.
What controls the release of anterior pituitary hormones?
Hypothalamic releasing hormones
- Sythesized in the parvocellular neurons
- transported via axons to median eminence
- Released from nerve terminarls into hypophyseal portal vein (primary capillaries)
- Travel down to the secondary capilalries where they act on anterior pituitary cells to stimulate or inhibit the release of hormones.
What are the 4 excitator hormones released from the anterior pituitary lobe?
TRH–> TSH
GnRH–> FSH, LH
CRH–> ACTH, B-ED
GNRH–> GH
What are the two inhibitory hormones released by the hypothalamus?
Somatostatin–> GH
DA–> PRL
If a pituitary stalk was sectioned, what hormonal changes would occur?
Increased prolactin (lose inhibitory DA)
DECREASED vasopressin and oxytocin
DECREASED GH, TSH, FSH, LH, ACTH, B-ED
What are the two disorders associated iwth abnormal hypothalamic pituitary function?
- Diabetes insipidus
- Galactorhhea amenorrhea
What is diabetes insipidus? Cause? Sx? Tx?
d/t a lack of vasopressin secretion
Caused by :
Head trauma (severing pituitary stalk) or autoimmune (destruction of the mangocellular neurons that produce vasopressin)
Sx: polyuria, polydypsia
Tx: vasopressin analogue
What is galactorhhea amenorrhea?
Sx?
Cause?
Tx?
Inappropriate lactiation and no periods!
Usually caused by a pituitary tumor that increases the production of prolactin which decreases the production of FSH/LH.
Tx: Surgery, dopamine receptor agonist (bromocyrptine)
Both decrease prolactin!
