endocrinology 2 Flashcards
What is the role of the hypothalamus?
integration centre for endocrine systems
What connects the hypothalamus and pituitary gland?
infundibulum
What is the true endocrine tissue of the pituitary gland?
anterior
How is the ant. pituitary connected to the hypothalamus?
2 connected capillary beds (portal system)
What is the tissue origin of the ant. pituitary?
epithelial
What portion of the gland doe the ant. make up?
2/3
What part of the pituitary is neuroendocrine tissue?
post
What is the tissue origin of the post pituitary?
neural
How does the post. pituitary connect to hypothalamus?
neural connection
What does the post. pituitary secrete?
neurohormones made in hypothalamus
What is the ant. pituitary also called?
adenohypophysis
What is the post. pituitary also called?
neurohypophysis
What peptide hormones does post. pituitary release?
vasopressin (anti-diuretic hormone; ADH)
oxytocin
Where are ADH and oxytocin synthesised?
magnocellular neurones in the hypothalamus
- different subsets (neurones) make either oxytocin or ADH
do the hypothalamus axons projecting down the infundibulum synapse with other neurones?
no, terminals end directly in capillaries
how are the mature neuronal hormones stored n the post. pituitary?
hormones stored in vesicles in the post. pituitary
What do the ADH and oxytocin behave like?
peptide hormones
What connects the cys in the ADH and oxytocin backbone?
disulphide bonds
Name the amino acids different in the ADH and oxytocin?
Phe –> lle
Arg –> leu
What is the main function of vasopressin (ADH)?
regulated water balance
What is the main function of oxytocin?
milk ejection and uterine contraction
What triggers the vasopressin (ADH release)?
increase plasma osmolarity (dehydration)
decrease volume/BP
What triggers the release of oxytocin?
suckling
labour (babies head against cervix)
What is the site/mode of action of vasopressin (ADH)?
KIDNEY COLLECTING DUCTS
- increase water reabsorption
VASCULAR SMOOTH MUSLCE
- increase BP
What is the site/mode of action of oxytocin?
MILK DUCT SMOOTH MUSCLE
- contracts muscle, ejecting
UTERINE SMOOTH MUSCLE
- child birth
What do you call hormone which control the release of other hormones (anterior pituitary to other endocrine targets)?
trophic hormones
What are the 2 pathways of the ant. pit?
direct on peripheral targets
indirect: trophic hormones to other endocrine targets and then to peripheral targets
What are the hormones from the ant. pit which act directly on peripheral targets?
prolactin, growth hormone
What happens of there is lack of or too much trophic hormone input?
lack of… atrophy
too much… hypertrophy
Why does the ant. pit use the portal system?
allows only a small vol of blood for these hormones to move around
we only need small amount of hormone to elicit effects
short distance, very rapid and dynamic
only need a small number or neurosecretory neurones for sufficient control
What 2 categories of hormones does the hypothalamus release to the ant. pit?
stimulatory or inhibitory
What is the only non-peptide hormones released by the hypothalamus?
dopamine (catecholamine)
steroid hormone
What is the role of dopamine on ant. pit?
prolactin-inhibiting hormone
What are all the hormones released by the ant. pit?
peptide hormones
What are the 6 peptiode hromones released ffrom the ant. pituitary?
prolactin
thyroid stimulating hormone
adrenocorticotropic hormone (ACTH)
growth hormone
follicle-stimulating hormone (FSH)
luteinising hormone (LH)
Does prolactin act directly on the breast?
yes, direct
What does TSH act on (AP)?
thyroid - thyroid hormone release
What does ACTH act on? (AP)
adrenal cortex - cortisol release
What does GH act upon? (AP)
liver - trophic
IGF release
or direct on growth tissues
What does FSH and LH act upon? (AP)
endocrine cells of gonads
What is the direct effect of FSH and LH? (AP)
regulation of reproductive function
What is the trophic effect of FSH and LH? (AP)
sex hormone release
What are the 2 types of hormone-specific cell types in the AP?
ACIDOPHIL CELLS
BASOPHIL CELLS
Name the 2 types of acidophil cells in the AP?
SOMATOTROPHS AND LACTOTROPHS
What does the somatotroph cell release in the AP?
GH
What does the lactotrophs release in the AP?
PL
wHAT DO THE THYROTROPHS RELEASE?
TSH
What do the gonadotrophs release?
LH/FSH
What do the corticotrophs release?
ACTH
What do the AP hormone-specific cell types allow?
the receptor profiles of these cells allow selectivity to incoming hypothalamic hormones
How is the AP controlled?
AP feedback control
What does the AP feedback control involve?
3 integration centres
- hypothalamus
- AP
- target endocrine cell
Do hormones act as a positive or negative feedback signal?
negative
What do you call the feedback from the endocrine target?
long loop feedback
What do you call the feedback from anterior pituitary to hypothalamus?
short loop feedback
