Entering into the medulla of the kidney, FTP, name this circular part of the nephron named after its discoverer.
A site of countercurrent multiplier systems, diuretics such as furosemide and bumetanide act here.  Ending at the macula densa, it is divided into two thin and two thick portions.  The descending arm is very permeable to water, but not permeable to salts, while the ascending limb is not permeable to water, but is permeable to salts and later actively reabsorbs them.  Entering into the medulla of the kidney, FTP, name this circular part of the nephron named after its discoverer.
A site of countercurrent multiplier systems, diuretics such as furosemide and bumetanide act here.  
loop of Henle