Term
Which of the following is not associated with a tumor and what clinical syndromes are associated with each?
GH, 2) ACTH, 3) FSH/LH, 4) Prl, 5) TSH |
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Definition
| Answer: FSH/LH released by gonadotropes….acromegaly, cushing’s syndrome, None, prolactinoma, hyperthyroidism |
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Term
Which of the following is false:
ACTH feeds back directly from the pituitary to the hypothalamus
ACTH feeds back directly from the end organ to the hypothal
Cortisol feeds back directly from the end organ to the pituitary and the hypothalamus
CRH, a trophic hormone and releasing factor, acts to promote ACTH from both the hypothalamus and pituitary |
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Definition
It's cortisol that feeds back from the end organ to the hypothal and pituitary
#2 is wrong |
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Term
Which of the following is true about a 44 AA long hormone commonly found in pancreatic tumors?
1. It feeds back negatively to the pituitary
2. It promotes the release of a hormone from the pituitary
3. It feeds back negatively to the hypothalamus
4. It’s direct stimulation of its target causes IGF-1 to feedback to the pituitary and hypothal
5. Its direct stimulation of its target causes SRIF to feedback negatively to the hypothalamus |
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Definition
2 is true,
SRIF/IGF-1 feed back negatively to the hypothal (IGF-1 also feedsback to the pit)
4, 5 are true |
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Term
| This substance that octreotide is derived from has what functions on which target? |
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Definition
| Somatostatin SRIF – inhibits secretion of GH/TSH and inhibits GI hormones and functions |
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Term
| What two hormones activate the prolactin receptor? |
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Definition
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Term
| Prl is inhibited by _______ which is released from where and acts where? |
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Definition
| Dopamine released from the hypothal counteracts PRF to inhibit Prl release from the pituitary. |
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Term
| How can there be direct hypothalamic stimulation of milk production? |
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Definition
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Term
Bromocriptine is a medicine that does what?
Tricyclic antidepressant
Binds GABA to reduce prolactin secretion
Inhibits TRH to inhibit prolactin
Binds dopamine to inhibit prolactin |
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Definition
4
Prolactin-inhibiting factors (PIFs)
Dopamine, Dopamine, Dopamine, maybe GABA
Bromocriptine is a dopamine agonist
Block multiple aspects of lactotrope function
Prolactin-releasing factors (PRFs)
TRH - but probably not physiologically important
Other candidates: AVP, VIP, Oxytocin, PHI-27 |
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Term
| T/F: TRH/Thyrotropin, a part of the glycoprotein hormone family stimulates the synthesis of T3 more than T4. |
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Definition
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Term
| T/F: TSH, an example of a glycoprotein hormone, has alpha and beta subunits that are glycosylated and confer biologic and immunologic specificity. |
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Definition
| F: only beta subunits conf specificity although both are glycosylated |
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Term
| What are the contributions of pulsatile and constant secretion of GnRH and how can this be used clinically? Does pulse frequency matter? |
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Definition
Pulsatility and pulse frequency are critical
Pulsatile infusion stimulates LH and FSH secretion
Constant infusion inhibits LH and FSH secretion
GnRH can be used to induce fertility and suppress gonadal function |
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Term
Where does estrogen exert negative feedback after its conversion from LH?
How about inhibin after it's conversion from ____? |
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Definition
inhibin at the pituitary
estrogen at the pit and at the hypothal however it also exerts POSITIVE FEEDBACK HERE DURING OVULATION!, MORE SO AT THE PITUITARY! |
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Term
Circadian rhythms
VS
Ultradian |
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Definition
Circadian rhythms
Occur over the course of a day, and repeat daily
Characteristic of most endocrine functions
Examples: Cortisol secretion
Ultradian rhythms
Bursts (spikes) of hormone secretion
Can be superimposed on circadian rhythms
Physiologically important, particularly in reproduction |
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Term
| How can we regulate the infusion of GnRH to either 1) suppress LH/FSH to prepare for IVF, or 2) induce ovulation in women with hypothal disease? |
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Definition
GnRH
Pulsatile infusion at 90 minute intervals can induce ovulation in women with hypothalamic disease
Continuous infusion is used to suppress LH/FSH in preparation for in vitro fertilization
LH and FSH
Puberty is associated with pulses of greater frequency and amplitude |
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Term
| How do pulses of LH/FSH change in puberty? |
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Definition
LH and FSH
Puberty is associated with pulses of greater frequency and amplitude |
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Term
| Similarly if we use these infusion approaches for parathyroid hormone, what happens? |
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Definition
| Chronic or continuous exposure to parathyroid hormone leads to bone resorption and hypercalcemia whereas intermittent exposure stimulates bone formation. |
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Term
| 3 Groups of Pituitary Hormones? |
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Definition
Pituitary hormones fall into three groups
Glycoprotein hormones (TSH, LH, and FSH)
ACTH
Growth hormone and prolactin |
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