438 Chapter 18
Proximal convoluted tubule Distal convoluted tubule Collecting ductEfferent
arterioleAfferent
arterioleGlomerular^
capsule^
Glomerulus
Interlobular Cortex (^)
artery
Medulla
Descending (^)
limb (^)
Ascending^
Interlobular limb^
vein^
Peritubular
capillaries
Loop of Henle
To minor
calyx
Figure 18- 3 The anatomy of a nephron, the functional unit of a kidney.
(^) ®
Learning
Cengage ©
known as the glomerulus (glom-AIR-youlus). The outer
wall of Bowman’s glomerular capsule is known as the
parietal layer. A collecting space separates the inner
visceral layer from the outer parietal layer of the cap-sule.
Together, Bowman’s glomerular capsule and the enclosed
glomerulus make up what is called a renal corpuscle.
The visceral layer of Bowman’s capsule and the en-
dothelial capillary network of the glomerulus form an
endothelial-capsular membrane, which is the site of
fil-tration of water and solutes from the blood. This filtered
fluid now moves into the renal tubule.
Bowman’s capsule opens into the first part of the renal
tubule, called the proximal convoluted tubule, lo-cated
in the cortex. The next section of the tubule is called the
descending limb of Henle, which narrows in diameter
as it dips into the medulla of the kidney. The tubule then
bends into a U-shaped structure known as the loop of
Henle. As the tubule straightens, it increases in diameter
and ascends toward the cortex of the kid-ney. Here it is
called the ascending limb of Henle. In the cortex, the
tubule again becomes convoluted and is now called the
distal convoluted tubule. The distal con-voluted tubule
ends by merging with a large straight