Structure of nephron showing vascular supply and direction of fluid
flo w
Proximal convoluted tubule (PCT):
• First section of the renal tubule
• Located in cortex
• Composed of simple cuboidal epithelial
cells with brush borders of microvilli
Nephron loop
--------------------------------
• Second section of the renal tubule
• Located in cortex and medulla
• Can be long (juxtaglomerular nephrons) or
short (cortical nephrons)
• Consists of descending limb (thin) and
ascending limb (thin, thick)
• Descending and thin ascending limbs are
composed of simple squamous epithelial cells
• Thick ascending limb is composed of simple
cuboidal to low columnar epithelial cells
FLOW OF FLUID THROUGH
A
JUXTAMEDULLARY NEPHRON
Glomerular (Bowman's) capsule
Proximal convoluted tubule
l
Descending limb of the
nephron loop
I
Thin ascending limb of the
nephron loop
Thick ascending limb of the
nephron loop
Afferent arteriole
goes into glomerulus.
Efferent arteriole
leaves glomerulus.
Distal convoluted tubule (DCT):
• Third part of renal tubule
• Located in cortex
• Composed mainly of simple
cuboidal epithelial cells
• Last part of DCT is composed of
cells similar to the collecting ducts
Collecting duct:
• Extends from cortex into medulla
• Receives urine from DCTs of
several nephrons and conducts it
to papillary duct
• Composed of simple cuboidal
epithelium with
principal cells
and
intercalated cells
Peritubular capillaries
receive
substances reabsorbed by the renal
tubule from the filtrate.
Papillary
duct
receives urine from
collecting ducts.
Minor calyx
is a cuplike structure that
receives urine from the papillary duct.
Distal convoluted tubule
(drains into collecting duct)
The Urinary System Plays a Vital Role in Maintaining Homeostasis
443
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