Hypothalamic-Pituitary Axes Flashcards
Where do the hormones released from the pituitary gland act (generally)?
- Target organs
- Peripheral hormones
What hormones are released from the anterior pituitary gland?
- ACTH
- TSH
- LH
- FSH
- GH
- Prolactin (PRL)
What hormones are released from the posterior pituitary gland?
- ADH
- Oxytocin
The hormone released from the hypothalamus which acts on the pituitary gland is known as what?
Neurohormone
The hormone which is released from the pituitary gland which acts on the peripheral gland is known as what?
Trophic hormone
Which hormones released from the pituitary gland are active hormones?
GH and prolactin
Which hormones released from the pituitary gland stimulate the release of another hormone?
TSH
ACTH
LH
FSH
Which is the only hormone released from the pituitary gland to not have a direct stimulating hormone released from the hypothalamus?
Prolactin
What three things are measured to evaluate thyroid function?
fT3, fT4 and TSH
When may TSH not be a good marker of thyroid function?
Pituitary tumours or other causes of secondary thyroid problems
The hypothalamus releases what stimulating hormone in the thyroid axis?
Thyrotropin releasing hormone (TRH)
The anterior pituitary releases what hormone in the thyroid axis? What does this stimulate the release of?
TSH- releases thyroid hormones from the thyroid gland
What are the long and short negative feedback loops in the thyroid axis?
TSH from anterior pituitary inhibits further TRH from the hypothalamus
Thyroid hormones inhibit release of TRH from the hypothalamus and TSH from the anterior pituitary
What hormone does the hypothalamus produce in the adrenal axis?
Corticotrophin releasing hormone (CRH)
What hormone does the anterior pituitary produce in the adrenal axis? Where does this act?
ACTH- acts on the adrenal cortex to produce cortisol
How is cortisol secreted?
In a diurnal rhythm
What is cortisol deficiency?
Adrenal insufficiency
What is primary adrenal insufficiency?
Addison’s Disease
Where is the problem in primary adrenal insufficiency?
Adrenal glands
What is secondary adrenal insufficiency?
Pituitary disease
What is cortisol excess?
Cushing’s Syndrome
ACTH is high in a patient with Cushing’s syndrome. Give two possible causes?
- Pituitary origin
- Ectopic ACTH
ACTH is low in a patient with Cushing’s syndrome. Give the cause?
Adrenal origin