1. Urinary System: Dr. Larry Johnson Texas A&M University
Part 1 Kidney and nephron
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Dr. Larry Johnson Texas A&M University

2. Objectives Part 1 Kidney and nephron
Describe the structure of the kidney and distinguish between cortical and medullary organization.
Identify and differentiate between the portions of the nephron.
Trace blood flow through the kidney.
Describe the structural organization of the ureter, urinary bladder, and urethra.

3. hilum

4. URINARY SYSTEM - FUNCTION IN HOMEOSTASIS
RID BODY OF WASTE (UREA, URIC ACID, CREATININE, SALTS)
PRESERVES CONSTANCY OF EXTRACELLULAR FLUID IN COMPOSITION, VOLUME, AND pH
ENDOCRINE FUNCTION
SECRETE ERYTHROPOIETIN - RED BLOOD CELL PRODUCTION
PRODUCES RENIN - ALDOSTERONE RELEASE

6. hilum

7. Slide 32: Kidney (H&E) Calyx Apex of renal pyramid Renal calyx
CT adventia capsule
Calyx
Renal pyramind and calyx
Medulla
Renal pelvis
Cortex
Simple columnar to transitional-like epithelium of pyramid

10. Slide 32: Kidney (H&E)
Arcuate arteries
Segmental
vein
Copyright McGraw-Hill Companies
Blood flow: Renal artery > segmental artery > interlobar artery > arcuate artery > interlobular artery > afferent arteriole > glomerulus > efferent arteriole > peritubular capillaries (assoc. with convoluted tubules) OR vasa recta (assoc. with loop of henle) > interlobular vein > arcuate vein > interlobar vein > segmental vein > renal vein.
Interlobular artery

11. Juxtamedullary nephrons
Slide 32: Kidney (H&E)
Capsule
Cortex
Cortex
Medulla
Medulla
Arcuate arteries
Juxtamedullary nephrons
Medullary rays

12. KIDNEY FUNCTION BASED ON COMBINATION OF
cortex
FILTRATION
ACTIVE SECRETION
PASSIVE DIFFUSION
SELECTIVE
ABSORPTION 32
medulla

14. Evolution –
Animals escaping
predators
Fresh water
Salt water

15. PORTAL
ARTERIOLE

16. Function of a portal system?
ARTERIAL PORTAL SYSTEM
= CAPILLARY  PORTAL ARTERIOLE  CAPILLARY
afferent ARTERIOLE
efferent ARTERIOLE,
and
PERITUBULAR CAPILLARIES
Function of a portal system?
local change in blood composition whereby the first capillary modifies and second allows the change in composition to affect local cells near it.
1st
2nd
1st
2nd

18. Renal corpuscle
Copyright McGraw-Hill Companies

20. Cells of the GLOMERULUS and capsule
PARIETAL EPITHELIUM
PODOCYTE
MESANGIAL CELL
ENDOTHELIAL CELL

21. PARIETAL EPITHELIUM
PODOCYTE
MESANGIAL CELL
ENDOTHELIAL CELL
MESANGIAL CELLs SECRETE ERYTHROPOIETIN - RED BLOOD CELL PRODUCTION

22. Slide 32: Kidney (H&E) Bowman’s capsule Glomerulus Renal corpuscle
Urinary pole
Renal Corpuscle
Urinary space
Parietal
epithelium
Bowman’s capsule
Podocyte
Glomerulus
Renal corpuscle
Visceral
epithelium
Arteriole of
vascular pole
Juxtaglomerular
cells
Macula densa

23. 19713 kidney Glomerulus Proximal convoluted tubules
Distal convoluted tubules
Proximal
convoluted t
ubules

24. Slide 32: Kidney (H&E) Juxtaglomerular apparatus
Macula densa of distal tubule
Juxtaglomerular cells
Distal convoluted tubules
Proximal convoluted tubules
Microvilli
Brush border

27. 0 to 8 mg/dL protein in urine is considered normal.
Proximal convoluted tubules
0 to 8 mg/dL protein in urine is considered normal.
The brush border is involved in
reabsorption of protein.

28. 19713 Human kidney cortex
Proximal
convoluted tubules
Adventia capsule with
no mesothelium
The intense eosinophilia of the cytoplasm of cells in the proximal convoluted tubules results from the glycocalyx covering the brush border staining intensely eosinophilic and the high density of membranes within the cells. These membranes and the high density of PCTs in the cortex are responsible for the PCTs absorbing most of filtered water from the renal corpuscle.
Renal
corpuscle

29. Proximal convoluted tubules
Toulidine blue kidney
Proximal convoluted tubules
Urinary pole
PCT DCT
Glomerulus
Collecting ducts

31. EM 18b
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32. Slide 33: Kidney (PAS/Hematoxylin)
Basement membranes
are PAS positive
Brush border
of proximal tubule
stain PAS positive due to the rich the glycocalyx covering its numerous microvilli.
Distal tubule

33. EM 30 & 43

34. Components of the filtration barrier:
1. The fenestrations of the capillary endothelium, which blocks blood cells and platelets
2. The thick, combined basal laminae, or GBM, which restricts large proteins and some organic anions
3. The filtration slit diaphragms between pedicels, which restrict some small proteins and organic anions
EM 18a

35. filtrate
blood

36. GLOMERULUS - PASSIVE ULTRAFILTRATION (ball park values)
ENDOTHELIAL CELL
>600,000 MW
BASAL LAMINA >160,000 MW
FILTRATION SLITS
>70,000 MW

37. Histologic features and major functions of regions with renal tubules
Region of Tubule
Histological Features
Locations
Major Functions
Proximal convoluted tubules
Simple cuboidal epithelium
Cells well-stained with numerous mitochondria
Prominent basal folds and lateral interdigitations
Long microvilli, lumens often occluded
Cortex
Reabsorption of all organic nutrients, all proteins, most water and electrolytes
Secretion of organic anions and cations, H+, and NH4+
Thin limbs of Loop of Henle
Simple squamous epithelium
Few mitochondria
Medulla
Passive reabsorption of Na+ and Cl-
Thick ascending limb (TAL) of Loop of Henle
No microvilli
Medulla and medullary rays
Active reabsorption of various electrolytes
Distal convoluted tubules
Cells smaller than in proximal convoluted tubules
Short microvilli and basolateral folds
More empty lumens
Reabsorption of electrolytes
Principle cells of Collecting system
Most abundant
Cuboidal to columnar
Pale-staining
Distinct cell membranes
Medullary rays and medulla
Regulated reabsorption of water and electrolytes
Regulated secretion of K+
Intercalated cells of Collecting system
Few and scattered
Slightly darker staining
Medullary rays
Reabsorption of K+ (low-K+ diet)
Help maintain acid-base balance

39. Slide 32: Kidney (H&E) Thick ascending limb of loop of Henle
Copyright McGraw-Hill Companies
Thick ascending limb of loop of Henle
Thick descending limb of loop of Henle
Thin limb of loop of Henle
Collecting duct

40. 19713 kidney medulla Descending PT CD CD ThLH CD Cap TnLH Cap Cap CD

41. Kidney medulla (Lee’ s stain) – thin portion of loop of Henle
Blood capillaries
Loop of Henle
Collecting
tubule

42. Transitions
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43. Toulidine blue kidney Peritubular capillaries of the vasa recta 36748
Ascending loop of Henle
Peritubular capillaries
of the vasa recta
Distal tubules
Transition from ascending
loop of Henle to
distal tubules
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Descending
loop of Henle
Transition from
proximal tubules to
thin descending loop of Henle

44. Infolding of the basal cell membrane line up mitochondria
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Transitions from ascending loop
of Henle to distal tubules
Ascending portion of loop of Henle attached to the distal tubule
Infolding of the basal cell
membrane line up mitochondria
in cells of the distal tubule.

45. 36748
Ascending
loop of Henle
Distal tubule
Blood capillaries of the vasa recta
Descending loop of Henle

46. 19713 kidney CT CT
TnLH
ThLH CT CT
Cap CT
Cap

47. 458 kidney
Collecting duct

48. 32
cortex
medulla
Minor calyx

49. Many illustrations in these VIBS Histology YouTube videos were modified from the following books and sources: Many thanks to original sources!
Bruce Alberts, et al Molecular Biology of the Cell. Garland Publishing, Inc., New York, NY.
Bruce Alberts, et al Molecular Biology of the Cell. Garland Publishing, Inc., New York, NY.
William J. Banks, Applied Veterinary Histology. Williams and Wilkins, Los Angeles, CA.
Hans Elias, et al Histology and Human Microanatomy. John Wiley and Sons, New York, NY.
Don W. Fawcett Bloom and Fawcett. A textbook of histology. W. B. Saunders Company, Philadelphia, PA.
Don W. Fawcett Bloom and Fawcett. A textbook of histology. Chapman and Hall, New York, NY.
Arthur W. Ham and David H. Cormack Histology. J. S. Lippincott Company, Philadelphia, PA.
Luis C. Junqueira, et al Basic Histology. Lange Medical Publications, Los Altos, CA.
L. Carlos Junqueira, et al Basic Histology. Appleton and Lange, Norwalk, CT.
L.L. Langley, et al Dynamic Anatomy and Physiology. McGraw-Hill Book Company, New York, NY.
W.W. Tuttle and Byron A. Schottelius Textbook of Physiology. The C. V. Mosby Company, St. Louis, MO.
Leon Weiss Histology Cell and Tissue Biology. Elsevier Biomedical, New York, NY.
Leon Weiss and Roy O. Greep Histology. McGraw-Hill Book Company, New York, NY.
Nature ( Vol. 414:88,2001.
Arthur C. Guyton,1971.Textbook of Medical Physiology W.B. Saunders company, Philadelphia, PA
WW Tuttle and BA Schottelius Textbook of Physiology C.V. Mosby Co.
A.L. Mescher Junqueira’s Basis Histology text and atlas, 13th ed. McGraw
Douglas P. Dohrman and TAMHSC Faculty 2012 Structure and Function of Human Organ Systems, Histology Laboratory Manual - Slide selections were largely based on this manual for first year medical students at TAMHSC

50. End of the Urinary System: Part 1
Next Urinary System:
Part 2 Function and excretory ducts

51. Urinary System: Dr. Larry Johnson Texas A&M University
Part 2 Function and excretory ducts
36748
Dr. Larry Johnson Texas A&M University

52. Objectives: Part 2 Function and excretory ducts
Describe the structure of the kidney and distinguish between cortical and medullary organization.
Identify and differentiate between the portions of the nephron.
Trace blood flow through the kidney.
Describe the structural organization of the ureter, urinary bladder, and urethra.

53. hilum

55. 19713 kidney thin loop of Henle in cortex

56. The density of the cortex is dominated by the proximal convoluted tubules.
However, the thin loop of Henle can be found in the cortex too.

57. The greatest change in flow rate
occurs in the proximal tubule which
reabsorbs 80% of the filtrate.
Flow rate

58. Cortical
nephrons
Loop increases
temperature over
straight tube
with same
amount of heat
Juxtamedullay
nephrons

59. Peritubular
capillaries
Capillaries
of the
vasa recta

60. PERITUBULAR CAPILLARIES
ABSORBS LITERS/DAY FROM INTERSTITIAL SPACES; THUS, ~4 TIMES REABSORPTION OF VENOUS END OF ALL OTHER CAPILLARIES OF BODY
ENDOTHELIAL CELLS - EXTREMELY POROUS
COLLOIDAL OSMOTIC PRESSURE OF PLASMA PROTEINS
LOW CAPILLARY PRESSURE
PROXIMITY TO URINIFEROUS TUBULES
PERITUBULAR CAPILLARIES

61. peritubular
fenestrated endothelium

62. Rich blood supply of peritubular capillaries and vasa recta
cortex
260
Arcuate arteries
medulla

63. Countercurrent exchanger
Capillaries
of the
vasa recta

64. Countercurrent
Multiplier
Countercurrent exchanger
nephron

65. WW Tuttle and BA Schottelius
Textbook of Physiology
C.V. Mosby Co.

66. Juxtaglomerular apparatus

67. Juxtaglomerular apparatus

68. Renin granules in JG cells of Kidney (PAS)
258
Renin granules in JG cells of Kidney (PAS)

69. ANGIOTENSINOGEN
(PLASMA GLOBULIN)
RENIN
(ENZYME from JG cells)
ANGIOTENSIN 1
(PLASMA ENZYME)
ANGIOTENSIN II
(MOST POTENT VASOCONSTRICTOR)

70. INCREASED BLOOD PRESSURE
ANGIOTENSIN II
VASOCONSTRICTION ALDOSTERONE RELEASE
FROM ADRENALS
INCREASED BLOOD PRESSURE
INCREASED SODIUM
(WATER REABSORPTION BY DISTAL TUBULE)
INCREASED BLOOD VOLUME

71. Adrenal function Aldosterone stimulates Na+ resorption in:
distal tubule of kidney
gastric mucosa
salivary glands
sweat glands

73. Proteinuria Several diseases may induce proteinuria:
In diseases such as diabetes mellitus and glomerulonephritis, the glomerular filter is altered and becomes much more permeable to proteins, with the subsequent release of protein into the urine
Proteinuria is an indicator of many potential kidney disorders.
0 to 8 mg/dL protein in urine is considered normal.

75. kidney
cortex
medulla
Minor calyx

76. 458 kidney
Minor calyx

77. Fluid transport and ureters
All images Copyright McGraw-Hill Companies

78. Slide 34: Ureter (upper 1/3)2 3 4 5
1. Transitional epithelium
Transitional epithelium
2. Lamina propria
3. Longitudinal smooth muscle
4. Circular smooth muscle
5. Adventia

79. Ureter – transitional epithelium and smooth muscle
The shape of the urethral lumen is
semi-lunar and slit-like

82. Slide 35: Urinary bladder6 5 4 3
Transitional epithelium
6. Serosa 2
5. Outer longitudinal smooth muscle 1
4. Middle circular smooth muscle
3. Inner longitudinal smooth muscle
2. Lamina propria
1. Transitional epithelium

85. Urinary bladder, monkey

86. Urinary bladder Nerve and mesothelium Transitional epithelium
Smooth muscle
160

88. Human Penis – transitional epithelium and surrounding spongy cavernous of penal urethra

89. Slide 98: Penile urethra (monkey)
Transitional epithelium

90. Differentiating between tubules in the cortex
Study Guide
Differentiating between tubules in the cortex
Proximal convoluted tubules
most numerous around the renal corpuscle
taller cuboidal cells
brush border with small lumen
intensely eosinophilic
Distal convoluted tubules
smaller cuboidal cells
proportionally larger lumen
less intensely eosinophilic
macula densa

91. Differentiating between tubules in the Medulla
Study Guide
Differentiating between tubules in the Medulla
Thick descending limb
Intensely eosinophilic (resembles proximal convoluted tubule)
More cuboidal than proximal convoluted tubule
Thick ascending limbs
Cuboidal
Less intensely eosinophilic (resembled distal convoluted tubule)
Confused with collecting duct, but no distinct cell boundaries, no scalloped appearance
Thin limb
Simple squamous epithelium
Nuclei often bulge into the lumen
Capillaries
Nuclei do not bulge into the lumen
Blood cells sometimes present
Collecting ducts
Tall cuboidal to columnar epithelium
Light staining similar to distal convoluted tubule
Apical surface often appears “scalloped”
Distinct lateral cell boundaries

94. Cortical
nephrons
Juxtamedullay
nephrons

95. Cortical
nephrons
Juxtamedullay
nephrons

96. Functions of the Urinary system

97. Many illustrations in these VIBS Histology YouTube videos were modified from the following books and sources: Many thanks to original sources!
Bruce Alberts, et al Molecular Biology of the Cell. Garland Publishing, Inc., New York, NY.
Bruce Alberts, et al Molecular Biology of the Cell. Garland Publishing, Inc., New York, NY.
William J. Banks, Applied Veterinary Histology. Williams and Wilkins, Los Angeles, CA.
Hans Elias, et al Histology and Human Microanatomy. John Wiley and Sons, New York, NY.
Don W. Fawcett Bloom and Fawcett. A textbook of histology. W. B. Saunders Company, Philadelphia, PA.
Don W. Fawcett Bloom and Fawcett. A textbook of histology. Chapman and Hall, New York, NY.
Arthur W. Ham and David H. Cormack Histology. J. S. Lippincott Company, Philadelphia, PA.
Luis C. Junqueira, et al Basic Histology. Lange Medical Publications, Los Altos, CA.
L. Carlos Junqueira, et al Basic Histology. Appleton and Lange, Norwalk, CT.
L.L. Langley, et al Dynamic Anatomy and Physiology. McGraw-Hill Book Company, New York, NY.
W.W. Tuttle and Byron A. Schottelius Textbook of Physiology. The C. V. Mosby Company, St. Louis, MO.
Leon Weiss Histology Cell and Tissue Biology. Elsevier Biomedical, New York, NY.
Leon Weiss and Roy O. Greep Histology. McGraw-Hill Book Company, New York, NY.
Nature ( Vol. 414:88,2001.
Arthur C. Guyton,1971.Textbook of Medical Physiology W.B. Saunders company, Philadelphia, PA
WW Tuttle and BA Schottelius Textbook of Physiology C.V. Mosby Co.
A.L. Mescher Junqueira’s Basis Histology text and atlas, 13th ed. McGraw
Douglas P. Dohrman and TAMHSC Faculty 2012 Structure and Function of Human Organ Systems, Histology Laboratory Manual - Slide selections were largely based on this manual for first year medical students at TAMHSC

98. End of the Urinary System: Part 2

99. The End!
My wife’s horse
Sam