intro to endo 1 W6 Flashcards
what do hormones control the rate of
enzymatic reactions
transport of ions/molecules across cell membranes
gene expression and protein synthesis
hormones and half life?
half life = time required to reduce hormone by half
how is action of hormones terminated
hormones bound to membrane receptors are degraded by plasma enzymes, endocytosis, intracellular enzymes metabolize hormones in cell
3 classifications of hormones
peptide (or protein) hormones
steroid hormones
amine hormones
peptide hormones structure
3 amino acids, large proteins, glycoproteins
what are steroid hormones derived from
cholesterol
what are amine hormones derived from
tryptophan or tyrosine
peptide hormones - precursors?
preprohormone (large, inactive)
prohormone (post-translational modification)
peptide hormone synthesis?
amino acids bind into peptide chain (preprohormone)
directed to ER lumen by signal sequence of amino acids
ER enzymes remove signal sequence (creating prohormone)
ER -> golgi complex
secretory vesicles bud off golgi
enzymes chop prohormone into active peptides and peptide fragments
exocytosis releases hormone into circulation
features of peptide hormones
water soluble
short half life (minutes)
bind to membrane receptors
signal transduction through cAMP production
insulin-tyrosine kinase
other signal transduction mechanisms
features of steroid hormones
made in adrenal cortex, gonads, adrenal medulla
steroid-producing cells have large amounts of smooth ER
steroid hormones only synthesised when needed (not stored in vesicles)
leave cell by simple diffusion
slower acting, longer half life
which steroid hormones are made in the adrenal cortex
aldosterone
cortisol
which steroid hormones are made in the gonads
oestrogens
progesterone
andorgens
which steroid hormones are made in the adrenal medulla
epinephrine
norepinephrine
(amine hormones)
result of steroid hormones being cholesterol-derived?
lipophilic and can enter target cell
location of steroid hormones target receptors?
cytoplasmic or nuclear
steroid hormones mechanism of action?
unbind from protein carrier in blood and diffuse into target cell or bind to membrane receptors (which use second messenger systems)
hormones which diffuse into cell bind to receptors in cytoplasm/nucleus that bind to DNA and activate/repress genes.
activated genes create new mRNA that are translated to produce new proteins
what do steroid hormones activate and why
activate DNA for protein synthesis
amine hormones derived from tyrosine - structure?
one ring structure - catecholamines (adrenaline, noradrenaline, dopamine)
two ring structure - thyroid hormones
which receptors do different structures of tyrosine derived amine hormones bind to
one ring structure - membrane receptors
two ring structure - intracellular receptors that activate genes
