Endocrinology: Hypothalamic Hormones Flashcards
Where is the paraventricular nucleus located?
- Adjacent to the 3rd ventricle, within blood-brain barrier
What two types of neurones does the paraventricular nucleus have?
- Magnocellular
- Parvocellular
What two hormones do magnocellular neurones produce?
Paraventricular nucleus
- Oxytocin (and supraoptic nucleus)
- ADH
What three hormones do parvocellular neurones produce?
Paracentricular nucleus
- CRH
- ADH (and supraoptic nucleus)
- TRH
What two hormones does the arcuate nucleus produce?
- Dopamine
- GHRH
What hormone does the pre-optic nucleus produce?
GRH
What hormone does the peri-ventricular nucleus produce?
- Somatostatin
What is the effect of dopamine on prolactin?
Dopamine inhibits prolactin
How many dopamine receptor types exist?
Five
Which three locations produce dopamine?
- Substantia nigra
- Arcuate nucleus
- Medulla of the adrenal glands
What are the 5 functions of dopamine?
- Role in behaviour, cognition and voluntary movements
- Inhibits prolactin
- Inotropic
- Chronotropic
- Induces vomiting via CTZ (metoclopramide is a dopamine antagonist)
What two enzymes metabolise dopamine?
- Catechol-0-methyl transferase (COMT)
- Monoamine oxidase (MAO)
True or false - Dopamine does not cross the blood-brain barrier
True or false - Dopamine does not cross the blood-brain barrier True.
What type of release is GnRH?
Pulsatile
What is the pulsatile release frequency of GnRH during follicular and luteal phases respectively?
- GnRH pulsatile frequency is high in follicular phase
- GnRH pulsatile frequency slows in the luteal phase
What is the pulsatile release frequency of GnRH during follicular and luteal phases respectively?
- GnRH pulsatile frequency is high in follicular phase
- GnRH pulsatile frequency slows in the luteal phase
What is the half life of GnRH?
2-4 mins
What chromosome is GnRH gene located on?
Chromosome 8
Is GnRH activity high or low in childhood?
Low
What is the effect of insulin on GnRH?
Insulin increases GnRH activity
What is the effect of prolactin on GnRH activity?
Prolactin decreases GnRH activity?
What is the effect of somatostatin on GnRH?
Somatostatin inhibits GnRH
Where is somatostatin secreted from?
Five locations
- Stomach
- Intestines
- Pancreatic D-cells
- Thyroid (para-follicular cells)
- Periventricular nucleus
What five inhibitory functions does somatostatin have?
- Inhibition of growth hromone
- Inhibition of TSH
- Supression of release of GI hormones (seven)
- Decreases gastric emptyng, blood flow and intestinal contractions
- Suppresses release of pancreatic hormones
