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Marieb’s Human
Anatomy and Physiology
Ninth Edition
Marieb w Hoehn
Chapter 25
Urinary system
Lecture 15
Part 1:
Urinary System Overview;
Functions of the Kidneys
• Make urine
• Regulate blood volume and blood pressure
• Regulate plasma concentrations of Na+, K+,
Cl-, HCO3-, and other ions
• Help to stabilize blood pH
• Conserve valuable nutrients
• Assist the liver in detoxification and
deamination
2
Urinary System
Figure from: Hole’s Human A&P, 12th edition, 2010
Kidneys receive about 1.2 L of blood per minute and
filter nearly 180 L of fluid from the bloodstream every
day!
3
Location of Kidneys
Figure from: Martini, Anatomy &
Physiology, Prentice Hall, 2001
Located
retroperitoneally
from T12 to L3
Left kidney is
slightly higher
than right kidney
Adrenal glands sit
on the medial and
superior part of
kidneys
Nephro(s) = kidney
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Location of Kidneys
Helps
maintain
position of
kidney
Figure from: Martini, Anatomy & Physiology, Prentice Hall, 2001
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Gross Anatomy of the Kidneys
Renal capsule is tough,
fibrous capsule (tunica
fibrosa)
Hilus is entry point for
renal artery, vein, and
nerve (mostly
sympathetic fibers)
[Pyel(o)-]
Bases of renal
pyramids face the
cortex, apices face the
renal pelvis and end at
renal papillae
Figure from: Martini, Anatomy & Physiology, Prentice Hall, 2001
6
Renal Blood Vessels
Glomeruli
(Cortical
radiate
arteries)
Minor Calyx
Figures from:
Martini, Anatomy
& Physiology,
Prentice Hall,
2001
Nerves, mainly sympathetic postganglionic fibers of the
ANS, follow arteries to nephrons
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The Nephron
(80%)
(20%)
Nephrons are
the structural
and functional
units of the
kidney
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Figure from: Hole’s Human A&P, 12th edition, 2010
Blood Supply of the Nephron
Medulla
The capillary loop of
the vasa recta is a
type of capillary
that is closely
associated with the
nephron loop of
juxtamedullary
nephrons
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Figure from: Hole’s Human A&P, 12th edition, 2010
Blood Flow Through Kidney and Nephron
Know
this!
10
Figure from: Hole’s Human A&P, 12th edition, 2010
Renal Corpuscle (Glomerulus + Capsule)
Figure from: Hole’s Human A&P, 12th edition, 2010
(Bowman’s)
Filtrate in
capsular
space
Notice that
the efferent
arteriole is
smaller than
the afferent
arteriole
This creates a
high pressure
(~55-60 mm
Hg) in the
glomerular
capillary bed
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Visceral Glomerular Epithelium
Figure from: Hole’s Human A&P, 12th edition, 2010
Material
passing out of
the blood must
be small
enough to fit
through the
filtration slits
(slit pores)
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Renal Cortex and Renal Medulla
Figure from: Hole’s Human A&P, 12th edition, 2010
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