Pituitary Physiology Flashcards
How is the anterior pituitary controlled?
There is an indirect control through the release of regulatory hormones via a blood connection from the hypothalamus
How is the posterior pituitary controlled?
Through the direct release of hormones from the hypothalamus
There is a neuronal connection to the brain
What is the only pituitary hormone not under positive control from the hypothalamus?
Prolactin - it is under tonic inhibition by dopamine
What is the ‘paired hormone’ concept?e
The various types of hormones are paired with on pituitary/central hormone and one peripheral hormone
Name some paired hormones of the anterior pituitary…
ACTH - Cortisol
TSH - Thyroxine
LH/FSH - Testosterone/Oestradiol
GH - IGF-1
What does the usual pituitary blood test detect?
TSH fT4 LH FSH Testosterone GH IGF-1 PRL
What are the two hormones STORED in the posterior pituitary?
Vasopressin
Oxytocin
They are produced by the hypothalamus and delivered to the posterior pituitary to be stored
What are some examples of dynamic pituitary tests?
Synacthen (Synthetic ACTH test)
Insulin Stress Test
Prolonged Glucagon Test
Water Deprivation Test
Which hormone stimulates ACTH production?
Cortisol Releasing Hormone
What cranial nerve is most commonly affected by and enlarging pituitary gland?
CN II - Optic Nerve
What are the five major pituitary axes?
Gonadotropin axis Growth axis Prolactin Thyroid axis Adrenal axis
How are the hormones from the hypothalamus transported to the posterior pituitary?
Along axons
What stimulates the release of thyroxine?
TRH acts on the pituitary to stimulate the release of TSH which stimulates the release of Throxine from the thyroid
What stimulates the release of Oestrogen and Testosterone?
GnRH acts of the pituitary to stimulate the release of LH and FSH. These act on the ovaries and testes
What stimulates the release of growth hormone?
GHRH is released from the hypothalamus and acts on the pituitary to release GH
