Pituitary Gland Flashcards
what regulates prolactin?
dopamine - inhibitory, the less dopamine, the more prolactin produced
what is the hypothalamic stimulus for TSH?
thyrotropin releasing hormone
what is the hypothalamic stimulus for FSH and LH?
gonadotropin releasing hormone
anterior pituitary produces which 5 types of hormone?
growth hormone prolactin thyrotrophin gonadotrophins corticotropins (LH & FSH)
Where are the receptors for these 5 anterior pituitary hormones? 1. growth hormone 2. prolactin 3. thyrotrophin 4. gonadotrophins 5. corticotropins (LH & FSH)
- muscle tissue, bone 2. mammary glands 3. thyroid gland (in neck) 4. gonads - ovaries and testes 5. adrenal glands above kidneys (like a chinese hat)
which scan do we use to look at pituitary gland? eg. in case of a tumour
What might happen if there was a tumour in the pituitary gland in terms of vision?
coronal scans using MRI
It would squash the optic chiasma, making one lose his peripheral vision which patients can be unaware of
large pituitary tumour which has risen up through sella turcica
what is it called when we lose our peripheral vision?
bitemporal hemianopia
which receptors does growth hormone bind to?
muscle, bone, liver –> intermediate which produces insulin-like growth factor (IGF-1)
too much growth hormone causes what exactly…
a) before puberty?
b) as an adult?
gigantism (height)
acromegaly (height doesn’t increase but everything else grows bigger)
Symptoms of acromegaly?
Why do adults get acromegaly when they have too much growth hormone instead of gigantism?
- coarsening of facial features
- macroglossia (large tongue), prominent nose
- large jaw - prognathism
- Increased hand and feet size
- sweatiness
- headache
Their epiphyseal plates have fused
name the two posterior pituitary hormones
arginine vasopressin (anti-diuretic hormone)
oxytocin
what is diuresis?
production of urine
what is the main physiological action of vasopressin?
How does it do this?
- anti-diuretic hormone
stimulation of water reabsorption in the collecting duct
concentrates urine –> less urine
- stimulates aquaporin (water channel) insertion into collecting duct membrane allowing water to be reabsorbed from tubular lumen of the collecting duct and back into the blood
oxytocin causes which physiological functions?
- milk ejection
- uterine contraction during delivery of baby
Fill the boxes:
- Growth hormone releasing hormone (+) , somatostatin (-)
- dopamine (-)
- thyrotropin releasing hormone (+)
- gonadotrophin releasing hormone (+)
- corticotrophin releasing hormone (+)
- arginine vasopressin (+)
What is the definition of a hormone?
chemical messengers that travel in the blood
Which hormones are synthesised in inactive form, travel free in the blood and bind to membrane receptors?
Which hormones are synthesised from cholesterol, travel bound to proteins in the blood and bind intracellular targets?
peptide hormones
steroid hormones
How is secretion of anterior pituitary hormones controlled?
by secretion of releasing hormones and inhibitory hormones released from hypothalamus
which system connects hypothalamus and anterior pituitary?
hypophysial portal system
what is a prohormone?
a hormone that requires further processing ie. cleavage to release active hormone
how are peptide hormones stored?
In vesicles ie. they are only released in response to signal - regulatory secretion
how are steroid hormones stored?
They are not - they are released immediately after they are made ie. constitutitive secretion
how do peptide hormones produce their effect?
bind receptors on cell membrane and transduce signal using 2nd messenger system
how do steroid hormones produce their effect?
bind to intracellular targets to change gene expression directly
Where is the pituitary gland in relation to the mammillary body, optic chiasm, hypothalamus and sella turcica?
bear in mind this is the inferior view of the brain
anterior and superior to mammillary body
inferior to optic chiasm
inferior to hypothalamus
superior to sella turcica
how are hypothalamic regulatory factors transported to the anterior pituitary gland?
what is the median eminence rich in and where is it located?
portal circulation
blood vessels, part of hypothalamus located immediately adjacent to pituitary stalk
what happens at the median eminence?
hypothalamic parvocellular neurons terminate on the median eminence and release hypothalamic releasing/ inhibitory factors to capillary plexus in median eminence, which are then carried by portal circulation to anterior pituitary
what are the five main types of endocrine cell in the anterior pituitary?
somatotrophs
lactotrophs
corticotrophs
thyrotrophs
gonadotrophs
what is special about the hypothalamo-pituitary portal system
fenustrations (leaky)
