chapter 17- endocrine part 2 Flashcards
what are binding proteins ?
they prevent hormone from being down by hydrolytic enzymes after entering the bloodstream
what do binding proteins act as?
chaperones
what do these “chaperones” do?
protect hormones and remain intact and functional when arrive at target
what are bound hormones?
when hormones attach to binding proteins
do hormones bind to specific binding proteins?
yes
what is reversible action?
detach at target tissues
what are the hormones called when they detach from the target tissues?
free hormones
why are some hormones always free?
they do not have specific binding proteins
what type of hormones can diffuse through the capillary walls and bind to target tissues
ONLY free hormones
why can’t bound hormones diffuse?
too big to diffuse through
what do bound hormones act as?
a reservoir for hormones and if hormone levels decrease, bound hormones release from binding proteins
what are examples of water-soluble hormones ?
LH, TSH, ADH, PTH, insulin, EPI
what water-soluble hormones pass through the cell membrane?
no, but they travel easily in blood
what are examples of lipid-soluble hormones?
steroids (testosterone and estrogen) and thyroid hormones
can lipid-soluble hormones cross the cell membrane?
yes
what are the two classes of receptors?
nuclear and membrane-bound
what are nuclear receptors?
bound by lipid-soluble hormones (small and non polar)
what are membrane-bound receptors
bound by water-soluble hormones, which are large
can the nuclear receptor class diffuse through the PM?
yes- easily
where are the nuclear receptor class usually found?
usually found in the nucleus, may be found in the cytoplasm (moves to the nucleus when activated)
what affect does the nuclear receptor class have on gene transcription?
modifies gene transcription (makes RNA copy of DNA sequence) and stimulates synthesis of new proteins
true or false, the nuclear receptor class has a rapid effect on target cells
true
how are secondary sexual characteristics stimulated?
hormone-receptor complex binds to DNA to stimulate protein synthesis. testosterone stimulates protein synthesis which stimulates secondary sexual characteristics
can the membrane bound receptor class pass through the PM?
no
