Endo

Question 1

smooth endoplasmic reticulum

Answer 1

involved in synthesis and processing of hydrophobic compounds (ie lipids, phospholipids, and cholesterol derivatives aka STEROID HORMONES).

-SER contains 21-hydroxylase required for steroid and phospholipid biosynthesis

Question 2

where is 25-hydroxyvitamin D converted to 1,25-dihydroxyvitamin D and with what enzyme?

Answer 2

proximal renal tubule; 1-alpha-hydroxylase

Question 3

osteocytes secrete ______ when 1,25-dihydroxyvitamin D levels are high

Answer 3

fibroblast growth factor 23 (FGF23); inhibits 1-alpha-hydroxylase

(PTH activates 1-alpha-hydroxylase)