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 cells  Act 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 layer  Outer 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 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 layer  Detrus 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 epithelium  At 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