THE URINARY SYSTEM
Chapter 26
OBJECTIVES
Describe the functional organization of the
urinary system.
 Explain how the kidneys remove metabolic
products from the circulation to produce urine.


Labs
Macroscopic – Kidney Dissection
 Microscopic – Kidney slide investigation
 Urinalysis


Activity/Reading

Kidney Stones
3 PRIMARY FUNCTIONS



excretion: removal of organic waste products
from body fluids
elimination: the discharge of wastes products
into the environment
homeostatic regulation: control the volume and
solute concentration of blood plasma
VOCABULARY
kidneys
 urine
 urinary tract
 ureters
 urinary bladder
 urethra
 micturition (urination)

fibrous capsule
 perinephric fat capsule
 renal fascia
 hilum

KIDNEYS ARE HIGHLY VASCULAR STRUCTURES
CONTAINING FUNCTIONAL UNITS CALLED
NEPHRONS – THEY PERFORM FILTRATION,
REABSORPTION AND SECRETION
left kidney lies
slightly superior to
the right kidney
 between T-12 and L-3
(see page 231)
 Fig 26-2

Each kidney basically
hangs suspended by
collagen fibers from
the renal fascia and is
packed in a soft
cushion of adipose
tissue
 “floating kidney”????

THE KIDNEY
a typical adult kidney
is reddish-brown
 4 in x 2.2 in x 1.2 in
 weighs about 150 g
(5.25 oz)
 Fig 26-3
 Fig 26-4

BLOOD SUPPLY
Each kidney receives blood through a renal
artery
 Eventually reaches afferent arterioles which
deliver blood to the capillaries (of glomerulus)
supplying individual nephrons
 Blood leaves the glomerulus in efferent arterioles
and drains into small venules
 The blood eventually drains directly into the
renal vein


Fig 26-5 (c)
INNERVATION
kidneys and ureters are innervated by renal
nerves
 renal nerves – enter each kidney at the hilum
and follow the tributaries of the renal arteries to
reach individual nephrons
 Sympathetic innervation:

adjusts rate of urine formation by changing blood
flow and blood pressure at the nephron
 stimulates the release of renin, which ultimately
restricts the loss of water and salt in the urine by
stimulating reabsorption at the nephron
