intro to endo 1 W6

Question 1

what do hormones control the rate of

Answer 1

enzymatic reactions
transport of ions/molecules across cell membranes
gene expression and protein synthesis

Question 2

hormones and half life?

Answer 2

half life = time required to reduce hormone by half

Question 3

how is action of hormones terminated

Answer 3

hormones bound to membrane receptors are degraded by plasma enzymes, endocytosis, intracellular enzymes metabolize hormones in cell

Question 4

3 classifications of hormones

Answer 4

peptide (or protein) hormones
steroid hormones
amine hormones

Question 5

peptide hormones structure

Answer 5

3 amino acids, large proteins, glycoproteins

Question 6

what are steroid hormones derived from

Answer 6

cholesterol

Question 7

what are amine hormones derived from

Answer 7

tryptophan or tyrosine

Question 8

peptide hormones - precursors?

Answer 8

preprohormone (large, inactive)
prohormone (post-translational modification)

Question 9

peptide hormone synthesis?

Answer 9

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

Question 10

features of peptide hormones

Answer 10

water soluble
short half life (minutes)
bind to membrane receptors
signal transduction through cAMP production
insulin-tyrosine kinase
other signal transduction mechanisms

Question 11

features of steroid hormones

Answer 11

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

Question 12

which steroid hormones are made in the adrenal cortex

Answer 12

aldosterone
cortisol

Question 13

which steroid hormones are made in the gonads

Answer 13

oestrogens
progesterone
andorgens

Question 14

which steroid hormones are made in the adrenal medulla

Answer 14

epinephrine
norepinephrine
(amine hormones)

Question 15

result of steroid hormones being cholesterol-derived?

Answer 15

lipophilic and can enter target cell

Question 16

location of steroid hormones target receptors?

Answer 16

cytoplasmic or nuclear

Question 16

steroid hormones mechanism of action?

Answer 16

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

Question 16

what do steroid hormones activate and why

Answer 16

activate DNA for protein synthesis

Question 16

amine hormones derived from tyrosine - structure?

Answer 16

one ring structure - catecholamines (adrenaline, noradrenaline, dopamine)

two ring structure - thyroid hormones

Question 16

which receptors do different structures of tyrosine derived amine hormones bind to

Answer 16

one ring structure - membrane receptors
two ring structure - intracellular receptors that activate genes