Answer to Question 1
ANS: A
The juxtamedullary nephrons lie close to and extend deep into the medulla and are important for the concentration of urine. Concentration of urine is not associated with midcortical, cortical, or medullary nephrons.
Answer to Question 2
ANS: C
Mesangial cells lie between and support the capillaries. Mesangial cells have phagocytic ability similar to monocytes, release inflammatory cytokines, and can contract to regulate glomerular ca-pillary blood flow. The epithelium has specialized cells called podocytes from which pedicles (foot projections) radiate and adhere to the basement membrane. The macula densa are sodi-um-sensing cells. The pedicles interlock with the pedicles of adjacent podocytes, forming an elaborate network of intercellular clefts called filtration slits, or slit membranes.