The result of additional mergings from this point on is that
the urine drains into the kidney’s central cavity, the
via several hundred large medullary collecting ducts. The
renal pelvis is continuous with the ureter draining that kidney
There are important regional differences in the kidney
(see Figures 14–2 and 14–4). The outer portion is the
and the inner portion the
contains all the renal corpuscles. The loops of Henle extend
from the cortex for varying distances down into the medulla.
The medullary collecting ducts pass through the medulla on
their way to the renal pelvis.
All along its length, each tubule is surrounded by capil-
laries, called the
Note that we have
Basic structure of a nephron. (a) Anatomical organization. The macula densa is not a distinct segment, but a plaque of cells in the ascending
loop of Henle where the loop passes between the arterioles supplying its renal corpuscle of origin. The outer area of the kidney is called the
cortex and the inner the medulla. Two types of nephrons are shown—the juxtamedullary have long loops of Henle that penetrate deeply into
the medulla, while the cortical nephrons have short (or no) loops of Henle. Note that the efferent arterioles of juxtamedullary nephrons give
rise to long looping vasa recta, while efferent arterioles of cortical nephrons give rise to peritubular capillaries. (b)
See next page.
Loop of Henle