What structure(s) in the excretory system accept the reabsorbed substances and return them to the general circulation?
Nephron is the functional unit of kidney which helps in filtration of blood and selective reabsorption of materials from filtrate to produce urine for excretion.
To study the structure of nephron read THIS.
You would see that nephron has four different sections: Bowman's capsule, proximal convoluted tubule (PCT), Henle's loop and distal convoluted tubule (DCT).
Filtrate is formed at Bowman's capsule. Selective reabsorption of materials from filtrate takes place mainly along PCT along with water, also along the Henle's loop.