Endocrinology Flashcards
endocrine system
endocrine cells release hormones that are conveyed by blood stream and act on distant cells
synergistic
2 hormones greater than 1 alone
permissive
presence of one hormone necessary for another to have an effect
antagonistic
2 hormones oppose each others effects
competitive
2 hormones similar in structure compete
3 classes of hormones
steroids - synthesised from cholesterol
peptides - synthesised from amino acids
amino acids - synthesised from tyrosine
steroid hormones
small hydrophobic molecules
released immediately after synthesis
circulate in bound form
slow long lasting effects
peptide hormones
synthesised as preprohormones and stored prior to release
act on cell surface receptors via 2nd messenger systems
amino acids
stored for instant release
pulsatile
hormone released in short bursts
circadian
hormone released in 24 hour schedule e.g. melatonin
posterior pit. gland
neurohypophysis
consists of axons and nerve endings
anterior pit. gland
adenohypophysis
originates from Rathke’s ppouch
consists of endocrine tissue
oxytocin
released from post. pit.
breast contraction
uterine contraction
ADH
post. pit.
water regulation in kidney
hypothalamic hormones
majority stimulate release of other hormone
e.g. GHRH stimulates GH
TRH stimulates TSH
anterior pit. hormones
stimulate release of other hormones
e.g. corticotrophs = ACTH
somatotrophs
stimulate release of growth hormone
acute actions
release fatty acids from adipose tissue
gonadotrophs
stimulate release of sex hormones