Pituitary hormone regulation and presentation of pituitary disease Flashcards
describe the blood supply of the anterior pituitary
unusual as it receives no artery blood supply, but instead receives blood through a portal venous circulation from the hypothalamus
describe the pituitary- thyroid axis
Hypothalamus —-> TRH—–> Pituitary—> TSH——–> Thyroid
what does the thyroid produce ?
T3 + T4
describe the GH/ IGF-I axis
- The growth hormone/ IGF-I (insulin-like growth factor) axis begins at the hypothalamus which produces Growth Hormone Releasing Hormone (GHRH) or somatostatin (SMS), also known as growth hormone inhibiting hormone (GHIH).
- GHRH increases the amount of growth hormone produced by the pituitary, which then goes to the liver.
- GHIH decreases GH production from the pituitary so that less goes to the liver.
4.The liver produces IGF-I which reduces the production of GHRH.
summarise the GH/IGF-I axis ( increasing)
Hypothalamus -> GHRH -> pituitary -> Inc GH -> liver -> IGF-I -> hypothalamus -> dec GHRH
summarise the GH/IGF-I axis ( decreasing)
Hypothalamus -> SMS/GHIH -> pituitary -> dec GH -> liver -> dec IGF-I -> hypothalamus
what hormones does the hypothalamus regulate/secrete?
- GHRH&SMS * GnRH
- CRH
- TRH
- Dopamine
what hormones does the pituitary regulate/secrete?
- GH
- LH&FSH * ACTH
- TSH
- Prolactin
name 5 diseases of the pituitary
- Benign pituitary adenoma
- Craniopharygioma
- Trauma
- Apoplexy / Sheehans
- Sarcoid / TB
what are the three vital signs of presentation for diagnosing tumours?
- pressure on local structure. e.g optic nerves
- pressure on normal pituitary
- functioning tumour\
what disease could it be if there Is pressure on local structure. e.g optic nerves?
bitemporal hemianopia
what disease could it be if there Is pressure on normal pituitary?
hypopituitarism
what disease could it be if there Is a functioning tumour?
Prolactinoma
Acromegaly
Cushing’s disease
who is more likely to have prolcatinomas?
women
what does prolactinomas cause ?
loss of libido
visual field defect
