hormones, vadrenal/thyroid Flashcards
where are chemical messengers synthesised/released
endocrine glands
some facts about hormones
hormones diffuse into bloodstream, travels to tissue to give an effect, target tissues have receptors that bind to hormone, receptors can be on membrane or intracellular, slow acting, longer more sustained effects, most hormones metabolised by enzymes in liver, kidney, blood, excreted in urine/faeces
where are hormones metabolised
liver, kidney, blood
two categories of the endocrine system
primary endocrine organs, secondary endocrine organs
main function of primary endocrine organs
secrete hormones
name organs part of the secondary endocrine organs
heart, liver, kidney, skin, intestine
what does the neuroendocrine system do
balancing/adjusting hormone levels to control normal functions in the body
name the 3 hypothalamic pituitary axis (master regulators)
thyroid, adrenal cortex, gonads
name 3 types of functional hormones and describe them
releasing hormone- produced by hypothalamus to act on pituitary
tropic/stimulating hormone- produced by pituitary to act on other endocrine glands
non-tropic hormones- produced by endocrine glands to act on target tissue
what are endocrine glands and name 3
ductless glands, secrete hormones into interstitial fluid, diffuse into nearby blood vessels
pituitary, adrenal, thyroid glands
what do exocrine glands do and name 2
secrete product into associated duct
sweat and salivary gland
name different molecular types of hormones
peptide, steroid, amine, eicosanoid
what is autocrine signalling
bind receptors on the same cell
what is paracrine signalling
targets neighbouring cells
what is endocrine signalling
targets distant cells via bloodstream
what is neuroendocrine signalling
neuron targets distant cells via bloodstream
what are agonists
ligands that bind to a receptor and induce a response, full or partial activity, often conformational changes
what is an antagonist
ligands that bind to a receptor but dont induce a response, can compete with agonist to block or reduce activation
what are inverse agonists
binds to receptors and induce opposite response
properties of hormones
lipophilic- diffuse across membrane to bind to intracellular receptor, eg steroid and thyroid hormones
lipophobic- binds to receptors on cell surface, eg peptides, catecholamines, eicosanoids
how are peptide hormones transported in blood
hydrophilic, free/unbound in circulation, half life in serum is minutes
how are steroid and thyroid hormones transported in blood
hydrophobic, mostly bound to carrier proteins in blood plasma, protected by carriers, half life is hours/days
synthesis/storage/release of peptide hormones
preprohormone–> prohormone–> active hormone–> storage granules–> exocytosis in response to a signal (eg. ca+)
name 2 rhythmic hormones
cortisol and melatonin
what can cause hormone levels in blood to fluctuate
food, light, activity, circadian rhythms
signals that show endocrine failure/disorder
hormone excess- hypersecretion, hyperfunction
hormone deficit- hyposecretion, hypofunction
hormone resistant- target cells dont respond to hormone
what is a primary endocrine disorder and give example
problem in secreting gland
peripheral endocrine glands
what is a secondary endocrine disorder and give example
under/over stimulation by tropic hormones
pituitary abnormalities
etiology/causes of endocrine disorders (hyposecretions/underactivity)
congenital absence or malformation of endocrine tissue, failure of endocrine tissue due to injury/disease, tissue resistant in target cells, loss/faulty receptors, surgical removal of endocrine tissue/other iatrogenic effects
what are iatrogenic effects caused by
medical/therapeutic/diagnostic interventions eg. radiation, chemotherapy, surgery, ischaemia, prescription medicines