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PowerPoint® Lecture Slides prepared by Leslie Hendon,
University of Alabama, Birmingham
HUMAN ANATOMY
fifth edition
MARIEB | MALLATT | WILHELM
23
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
The Urinary System
PART 1
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
The Urinary System
Important functions of the kidneys Maintain the chemical consistency of blood Filter many liters of fluid from blood Send toxins, metabolic wastes, and excess water
out of the bodyMain waste products
UreaUric acidCreatinine
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Organs of the Urinary System
Kidneys Ureters Urinary bladder Urethra
Figure 23.1a
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Location and External Anatomy of Kidneys
Located retroperitoneally
Lateral to T12–L3 vertebrae
Average kidney 12 cm tall, 6 cm wide, 3 cm thick
Hilus On concave surface Vessels and nerves enter and exit
Renal capsule surrounds the kidney
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Relationship of the Kidneys to Vertebra and Ribs
Figure 23.1b
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Position of the Kidneys with in the Posterior Abdominal Wall
Figure 23.2a
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Internal Gross Anatomy of the Kidneys
Frontal section through the kidney Renal cortex Renal pyramids Renal pelvis
Major caliciesMinor calicies
Gross vasculature Renal arteries
Branch into segmental arteries
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Summary of Blood Vessels Supplying the Kidney
Figure 23.3c
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Internal Gross Anatomy of the Kidneys
Nerve supply – renal plexus A network of autonomic fibers An offshoot of the celiac plexus
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Internal Anatomy of the Kidneys
Figure 23.3b
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Microscopic Anatomy of the Kidneys
Uriniferous tubules Composed of
Nephron Renal corpuscle plus renal tubules
Collecting duct Involved in concentrating urine
PLAYPLAY Nephron
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Mechanisms of Urine Production
Filtration Filtrate of blood leaves kidney capillaries
Reabsorption Most nutrients, water, and essential ions reclaimed
Secretion Active process of removing undesirable molecules
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Basic Kidney Functions
Figure 23.4
PowerPoint® Lecture Slides prepared by Leslie Hendon,
University of Alabama, Birmingham
HUMAN ANATOMY
fifth edition
MARIEB | MALLATT | WILHELM
23
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
The Urinary System
PART 2
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Uriniferous Tubule
Figure 23.5a
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
The Nephron
Renal corpuscle Glomerulus and glomerular capsule
Glomerulus – tuft of capillariesCapillaries of glomerulus are fenestrated
Glomerular (Bowman’s) capsule Parietal layer – simple squamous epitheliumVisceral layer – consists of podocytes
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Renal Corpuscle and the Filtration Membrane
Figure 23.6a
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Renal Corpuscle and the Filtration Membrane
Figure 23.6c
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Tubular Section of Nephron
Filtrate proceeds to renal tubules from glomerulus Proximal convoluted tubule Loop of Henle
Descending limbThin segmentThick segment
Distal convoluted tubule
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Micrograph through the Renal Medulla
Figure 23.7
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Classes of Nephron
Cortical nephrons 85% of nephrons
Juxtamedullary nephrons 15% of nephrons
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Figure 23.8
Collecting Tubules (Collecting ducts)
Collecting tubules Receive urine from distal convoluted tubules
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Classes of Nephron
Figure 23.9a
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Microscopic Blood Vessels
Nephrons associated with two types of capillary beds (a portal system) Glomerulus
Fed and drained by arteriolesAfferent and efferent arterioles
Peritubular capillariesArise from efferent arteriolesLow-pressure, porous capillariesAbsorb solutes
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Microscopic Blood Vessels
Vasa recta Thin-walled looping vessels Part of the kidney’s urine-concentrating
mechanism
PowerPoint® Lecture Slides prepared by Leslie Hendon,
University of Alabama, Birmingham
HUMAN ANATOMY
fifth edition
MARIEB | MALLATT | WILHELM
23
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
The Urinary System
PART 3
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Microscopic Anatomy of the Kidney
Juxtaglomerular apparatus Functions in the regulation of blood pressure Juxtaglomerular cells – secrete renin
Macula densa A portion of distal convoluted tubule
Tall, closely packed epithelial cellsAct as chemoreceptors
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Juxtaglomerular Apparatus
Figure 23.10
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Ureters
Carry urine from the kidneys to the urinary bladder
Oblique entry into bladder prevents backflow of urine
Histology of ureter Mucosa – transitional epithelium Muscularis – two layers
Inner longitudinal layerOuter circular layer
Adventitia – typical connective tissue
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Microscopic Structure of the Ureter
Figure 23.12
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Urinary Bladder
A collapsible muscular sac
Stores and expels urine Full bladder – spherical
Expands into the abdominal cavity
Empty bladder – lies entirely within the pelvis
Figure 23.13
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Figure 23.14
Urinary Bladder
Urachus – closed remnant of the allantois
Prostate gland In males
Lies directly inferior to the bladder
Surrounds the urethra
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Urinary Bladder
Wall of bladder Mucosa
Transitional epithelium
Muscular layerDetrus or muscle
Adventitia
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Histology of the Urinary Bladder
Figure 23.15a, b
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Structure of the Urinary Bladder and Urethra
Figure 23.16a
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Structure of the Urinary Bladder and Urethra
Figure 23.16b
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Urethra
Epithelium of urethra Transitional epithelium
At the proximal end (near the bladder)
Stratified and pseudostratified columnar – mid urethra (in males)
Stratified squamous epitheliumAt the distal end (near the urethral opening)
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Urethra
Internal urethral sphincter Involuntary smooth muscle
External urethral sphincter Voluntarily inhibits urination Relaxes when one urinates
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Urethra
In females Length of 3–4 cm
In males – 20 cm in length – three named regions Prostatic urethra
Passes through the prostate gland Membranous urethra
Through the urogenital diaphragm Spongy (penile) urethra
Passes through the length of the penis
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Micturition
Figure 23.17
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Disorders of the Urinary System
Urinary tract infections More common in females Burning sensation during micturition
Renal calculi Kidney stones
Bladder cancer 3% of cancers – more common in men
Kidney cancer Arises from epithelial cells of uriniferous tubules
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
The Urinary System Throughout Life
Embryo develops three pairs of kidneys Pronephros Mesonephros Metanephros
Only metanephros persists to become the adult kidneys
Metanephric kidney produces urine by fetal month three
Contributes to the volume of amniotic fluid
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Development of the Urinary Organs
Figure 23.18a,b
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Development of the Urinary Organs
Figure 23.18c, d
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
The Urinary System Throughout Life
Kidney and bladder function declines with advancing age Nephrons decrease in size and number Tubules less efficient at secretion and reabsorption Filtration declines Recognition of desire to urinate is delayed Loss of muscle tone in the bladder
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