This document provides an overview of the renal (urinary) system, including its organs and their functions. It describes the internal and microscopic anatomy of the kidneys, including the structures within the kidneys like the renal capsule, renal fascia, and nephrons. It explains the structures and functions of nephrons, including glomerular filtration, reabsorption, and regulation of electrolytes and pH. It also discusses common kidney problems like kidney stones and their treatment options. Overall, the document concisely summarizes the key anatomical structures and physiological functions of the urinary system.

1. RENAL SYSTEM
1

2. Organs of the Renal System
Kidneys
Ureters
Urinary bladder
Urethra
Not many
structures, but
very important!
Figure 23.1a
2

3. Functions of Urinary System
Regulate electrolytes (K, Na, etc)
Regulate pH in blood
Regulate blood pressure
Regulate blood volume (removes excess
fluid)
Removing metabolic wastes
 Urea, uric acid, and creatinine
 This is the least important of the kidney’s functions.
You can survive for a few weeks without excreting
waste products in the urine, but hour by hour, the
other functions are more important.
3

4. Relationship of the Kidneys to
Vertebra and Ribs
They are retroperitoneal
and are located in the
abdominal cavity.
They are at the level of
T12 to L3, so they are at
the costal margin, and the
ribs protect them a little.
Even though they are
protected by thoracic ribs,
they are NOT in the
thoracic cavity because
they are below the
diaphragm.
Figure 23.1b
4

5. Position of the Kidneys with in
the Posterior Abdominal Wall
Figure 23.2a
5

6. STRUCTURES WITHIN THE
KIDNEY
The RENAL CAPSULE surrounds the kidney,
made of dense fibrous connective tissue.
A layer of adipose tissue surrounds the capsule,
called PARARENAL FAT (ADIPOSE). It
cushions and protects.
Around that is a connective tissue layer called
the RENAL FASCIA, made of loose connective
tissue. It anchors the kidney to the surrounding
peritoneum and abdominal wall. It is not very
strong; jumping up and down can cause tearing.
6

7. Vibration Platform Machine:
No longer used in the USA because it
damages kidneys!
7

8. These are still around in gyms in
other countries…beware!
8

9. Gross Anatomy of the Kidneys
 Renal cortex (Most superficial layer)

Renal medulla
Renal pyramids (drain into the calyx)
 Renal pelvis
Calyx (drains into hylus  ureter)
 Ureter
9

10. Renal fascia
Interlobar arteries
Interlobular arteries
Arcuate
arteries
10

11. Internal Anatomy of the Kidneys
Interlobar artery
Figure 23.3b
11

12. Blood Supply to Kidney
AORTA  RENAL ARTERY  SEGMENTAL ARTERIES 
INTERLOBAR ARTERIES  ARCUATE ARTERIES (form arcs) 
INTERLOBULAR ARTERIES
INTERLOBULAR VEIN  ARCUATE VEIN  INTERLOBAR VEINS
 SEGMENTAL VEINS  RENAL VEIN  INF. VENA CAVA
12

13. Internal Anatomy of the Kidneys
Interlobar artery
Figure 23.3b
13

14. Microscopic Anatomy of the Kidneys
Just like the functional unit of the lungs is
the alveolus and the functional unit of the
liver is the lobule, the functional unit of the
kidney is the NEPHRON.
Each kidney has about 1 million nephrons.
Each one carries out all of the various
functions of the kidneys.
14

15. Microscopic Anatomy of the Nephron
GLOMERULUS WITH A CAPSULE
PROXIMAL CONVOLUTED TUBULE
LOOP OF HENLE

DESCENDING LIMB
Thick portion
Thin portion
 ASCENDING LIMB
Thick portion
Thin portion
DISTAL CONVOLUTED TUBULE
COLLECTING DUCT 15

16. Nephron
16

17. Position of Nephron in Kidney
Figure 23.4a
17

18. Glomerulus of a Nephron
18

19. Juxtaglomerular Apparatus
 The distal end of the
renal tubule passes
next to the
glomerulus to form
the juxtaglomerular
apparatus (juxta
means “next to”).
 The juxtaglomerular
apparatus (JGA)
consists of cells
located in and
around the
glomerulus and the
glomerular capsule.
19

20. Juxtaglomerular Apparatus
 If blood pressure is
too low, the JGA
releases
adenosine, which
causes
vasoconstriction of
the afferent arteriole.
This will slow the
filtration rate so
less water is lost,
and blood pressure
increases.
20

21. Juxtaglomerular Apparatus:
Juxtaglomerular Cells
 if the blood pressure is
still too low after
adenosine has caused
vasoconstriction, the
JGA secretes the
hormone renin .
 Renin causes more
sodium to be
reabsorbed, and water
follows, so blood
volume increases, so
blood pressure
increases.
21

22. GLOMERULUS
The glomerulus is the first part of the nephron, where the
filtration occurs.
The glomeruli are located only in the renal cortex.
A glomerulus (“ball of yarn”) is a tuft of capillaries
surrounded by a glomerular capsule (Bowman’s capsule)
made of simple squamous epithelium. The glomerulus
fits in the capsule like a fist punched into an
underinflated balloon.
The capsule collects the plasma from the arterioles and
drains it into the convoluted tubules, which empty into a
collecting duct, which exits the body.
The plasma is further filtered along the way.
22

23. Glomerulus
of a
Nephron
23

24. Normally at the end of the capillary bed you
have venuoles. But this is the only part of the
body that is different: here we have another
arteriole, called the EFFERENT ARTERIOLE,
which takes blood away from the glomerulus.
The efferent arteriole drops down straight, next
to the Loop of Henle. While it is straight, it is
called VASA RECTA (straight capillaries).
There are capillaries that come off the vasa
recta which surround the loop of Henle. Here,
they are called peritubular capillaries. They then
leave the area to become the interlobular vein,
which leaves the kidney.
24

25. Nephron
25

26. Juxtaglomerular
apparatus
Efferent arteriole
Afferent arteriole
Bowman’s capsule
26

27. FUNCTION OF THE NEPHRON
Blood comes in from the AFFERENT ARTERIOLES.
Plasma leaks out and enters the glomerular capsule.
The plasma contains nutrients, waste products, etc. As
the plasma moves through the proximal convoluted
tubule, all of the nutrients, and most of the water, and
most of the ions are absorbed back out of the nephrons
and into the blood.
In the Loop of Henle, almost all of the rest of the water
and salt are removed  blood.
Everything that is not reabsorbed (the waste products)
goes into the collecting duct and is excreted as urine.
This is also how the water-salt balance is maintained, as
well as the acid-base balance.
27

28. Nephron
28

29. FUNCTION OF THE NEPHRON
In the distal convoluted tubule, the rest of the
water and salt are removed.
The rest of the liquid goes into the collecting
duct.
The distal convoluted tubule and the collecting
duct fine-tune the water and salt absorption and
excretion. If you are well hydrated, the water will
be allowed to leave as urine.
If you are thirsty, the water will be absorbed.
The purpose of the peritubular capillary bed is to
absorb these things from the nephron tubules
and put them back into the blood.
29

30. Figure 23.5
30

31. Renal Corpuscle and the
Filtration Membrane
Figure 23.6c
31

32. Function of the Nephron
http://www.youtube.com/watch?v=aQZaNX
6 Tips for healthy urinary system:
http://urology.about.com/od/infections/tp/5tipsf
32

33. Diuretics
Diuretics are medicines that increase the
amount of urine that is produced.
People who have high blood pressure might be
prescribed diuretics to decrease the blood
volume.
Alcohol is a diuretic and this is what
contributes to the symptoms of a hangover.
The best way to prevent a hangover after
drinking is to consume a lot of water before
you go to bed.
Caffeine is also a diuretic, so coffee and
regular Coca-cola are diuretics.
33

34. HISTOLOGY OF THE NEPHRON
PROXIMAL AND DISTAL CONVOLUTED
TUBULES
 This area absorbs nutrients, water, and salt.
Only about 1% of the fluid filtered by the
kidney actually becomes urine.
LOOP OF HENLE

This is where water is reabsorbed. It is
located in the renal medulla.
34

35. Urine Production
Filtration – filtrate of blood leaves kidney
capillaries
Reabsorption – most nutrients, water, and
essential ions reclaimed
Secretion – active process of removing
undesirable molecules
35

36. Figure 23.9a
36

37. Collecting Duct (tubule)
Receives urine from distal convoluted
tubules, empties into ureter.
Figure 23.4a
37

38. Ureters
These are long tubes that connect the renal
pelvis to the urinary bladder
MUCOSA
 TRANSITIONAL EPITHELIUM (for expansion)
 LAMINA PROPRIA (has elastic tissue to recoil)
MUSCULAR LAYER (smooth muscle)

INNER CIRCULAR

OUTER LONGITUDINAL
ADVENTITIA
 Provides protection, strength for organs, and
attaches ureters to surrounding structures
38

39. URINARY BLADDER
The histology of the urinary bladder is
identical to the ureter except the mucosal
layer has folds called RUGAE, which allow
for expansion.
The rugae have the same basic function
as transitional epithelium—
accommodating stretch as the bladder
fills.
You can hold up to one liter of urine,
although at 500 ml, you’ll be dancing. 39

40. Urinary Bladder
Rugae:
allows for
expansion
-A full
bladder is
roughly the
size of a soft
ball
Figure 23.14
40

41. URINARY BLADDER
The muscle layer around the urinary
bladder is thicker than the ureters, and is
called the DETRUSOR MUSCLE, which
contracts to allow emptying of the urinary
bladder.
The function of the urinary bladder is just
to store urine.
41

42. Detrusor Muscle
42

43. URETER entrance to BLADDER
The URETER enters in at the base of the
urinary bladder, not the top.
As the bladder fills, it presses down on the
ureters to prevent urine from backing up
into the kidneys.
43

44. BLADDER
The TRIGONE is a triangular area where the ureters
come in and the urethra goes out.
Between the urethra and the urinary bladder are two
sphincters:
INTERNAL URETHRAL SPHINCTER: smooth muscle
EXTERNAL URETHRAL SPHINCTER: skeletal muscle.
Although it is primarily under voluntary control, it will
contract if the urine volume is too much.
If the patient is in a coma or under anesthesia for a long
time, the internal sphincter will be closed, like when you
are asleep, so a catheter is needed to open it to drain
the urine out.
44

45. 45

46. Urethra
Drains the urine to the outside.
Its histology is the same as the ureter
Females: 4cm
Males 20 cm (varies with mood)
Therefore, women (esp. little girls) are
more susceptible to UTI.
46

47. Problems
URETHRITIS = infection and inflammation
of the urethra
PYELITIS= infection of the renal calyxes
CYSTITIS = infection of the urinary
bladder.
CHOLEOCYTITIS = infection of the gall
bladder
47

48. UREA
Urea is a waste product of amino acid
metabolism.
Remember, proteins are made of amino
acids, so when you break down proteins,
you break them down into amino acids,
and the waste product left over is urea.
This is the main waste product in urine.
Excessive proteins can cause kidney
damage, since they are acidic.
48

49. COLOR OF URINE
When you urinate, it should be clear and
colorless with almost no yellow color.
The more yellow the urine is, the more
dehydrated you are.
If the urine is very dark yellow, you are
burning too much protein (as in food
deprivation). This is often seen in
diabetes.
49

50. Problems
KIDNEY STONES

Develop in the renal pelvis
 Stones are made out of a variety of things:
uric acid, calcium, cystine (an amino acid), or
cholesterol.

They keep growing.
50

51. KIDNEY STONES
They can block the ureter, causing the kidney to
enlarge. As the kidney stretches, the capsule
stretches, causing excruciating pain in cycles of
hours. As pressure builds up around the stone,
urine can pass, and the kidney stone moves
down the urethra slowly.
Symptomatic kidney stones may be pea sized or
larger (up to 1 ½ inches).
They get stuck in three places:
 Renal pelvis
 In the ureter as it bends over the common iliac artery
 In the urinary bladder at the trigone.
51

52. Kidney
Stones
52

53. 5 cm Kidney Stone Surgery
53

54. Kidney stones get stuck in three places:
Renal pelvis
In the ureter as it bends over the common
iliac artery
In the urinary bladder at the trigone.
54

55. Where
kidney stones
get stuck
Renal pelvis
Ureter
Common
iliac
artery
Urinary
bladder
trigone
55

56. 56

57. KIDNEY STONES TREATMENT
ULTRASOUND LITHOTRIPSY

Put a powerful speaker on the outside of the kidney,
sends a shock wave which the tissues absorb, but the
stones shatter so the pieces can pass easier.
STENT
 (1 ½ foot long tube) in to keep the ureter open along
its entire length. Insert under general anesthetic,
remove without.
To help prevent kidney stones, drink enough
fluid so your urine stays clear and light colored.
57

58. ULTRASOUND LITHOTRIPSY
58

59. 59

60. Kidney Stone Prevention
60

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61

62. Other Kidney Problems
Nephritis: inflammation of the nephrons.
Hydronephritis: excess fluid in the nephron.
Glucose in the urine: indicates diabetes.
62

63. Kidney Problems
Things can happen to the kidney: infection,
excess proteins, pH change, blood pressure
drops, and can lead to kidney failure.
Treatment for kidney failure is DIALYSIS, which
removes blood, send it through a filter, and
return it without the wastes. It is done three
times a week, six hours a day. Ideally, they
need a kidney transplant because the kidney
has other functions as well.
The brain, heart, and kidney are the only three
organs in the body that have to get oxygen to
sustain life.
63

64. What is Renal Failure?
Renal failure occurs when your kidneys stop
working.
Our kidneys are very important to us because
we use them to remove waste from our bodies
And our kidneys keep the balance of water and
salt in our body.
If we are unable to regulate the water and
mineral balance in our body, Renal Failure can
be life threatening.
64

65. Causes of Renal Failure
1. Medication / Poison / Infection
People with long term health problems
are most at risk to have kidney problems
from medication.
- Antibiotics
- Pain Medication
- Blood Pressure Medicine
- Dyes used in X-rays
65

66. 2. Sudden drop in blood flow.
- Heavy blood loss from an injury
- A serious infection (Sepsis)
- Severe Dehydration
3. Blockage of fluid out of the Kidney
- Kidney Stones
- Tumor(s)
- Enlarged Prostate Gland
66

67. Who is most likely to get Renal
Failure?
Kidney or Liver Disease
Diabetes
High Blood Pressure
Heart Failure
Obesity
Bone Marrow Transplant
Heart or Belly Surgery
67

68. Symptoms
Very little or no urine during urination
If the body is unable to excrete potassium, the rising of
potassium levels is associated with ventricular
tachycardia and ventricular fibrillation. Lethal injections
are excess potassium.
Loss of appetite
As waste accumulates, lethargy and fatigue become
apparent to the point where mental function can
decrease to coma.
Body Weakness
Because of low levels of erythropoietin produced by
failing kidneys they do not stimulate the bone marrow
which leads to a decrease in red blood cells. This leads
to less oxygen throughout the body which leaves the
body unable to do work.
68

69. Symptoms
High Blood Pressure
Because the kidneys can not deal with the rising acid
levels in the body, breathing becomes more rapid as the
lungs attempt to blow off carbon dioxide to buffer the
acid levels. In doing so, fluid can be deposited in the
lungs possibly causing congestive heart failure.
Swelling of the legs and feet
Nausea and or Vomiting
Back pain below the rib cage, (Flank Pain)
Some people may not have any symptoms
(asymptomatic)
69

70. Diagnosis
Patients can be diagnosed by undergoing
blood and urine tests
Blood Urine
BUN Protein
-Blood Urea Nitrogen Abnormal presence of
Creatinine White and Red blood
-Waste product levels cells
GFR Electrolytes
-Glomerular Filtration Rate
70

71. Diagnosis
Patients can also undergo an Ultrasound to
see if there are any obstructions.
71

72. Treatment
Treatments are based on the cause
Issue Treatment
- Blood Loss - Restore blood flow
- Medication / Poison - Stop taking the
medication or poison
- Blockage - Remove or bypass
blockage
72

73. Also, the person treating the patient will
attempt to stop the buildup of waste in the
body. This may be done by dialysis.
And the person treating the patient may
also administer other medication to
prevent the retention of excess fluid and
minerals and prevent any further renal
damage.
-lowering Phophorus levels
-increase production of Red Blood Cells
-regulate blood pressure with medication
73

74. Prevention
Regulate Blood Pressure
Regulate Sugar Intake
Regulate Protein Intake
Once the kidney fails the only options are
dialysis and transplantation.
74

75. Values Results Normal
APPEARANCE CLEAR CLEAR
BACTERIA MODERATE NEG
BILIRUBIN NEGATIVE NEG
COLOR AMBER Straw
EPITHELIAL CELLS FEW FEW
ERYTHROCYTES 3-5/HPF (High) 0-2
GLUCOSE NEGATIVE NEG
HEMOGLOBIN NEGATIVE NEG
HYALINE CASTS 0-4/LPF 0-4
KETONES 1+ NEG
LEUKOCYTE ESTERASE 1+ NEG
LEUKOCYTES 6-10/HPF (High) 0-2
NITRITE NEGATIVE NEG
PH 6.5 4.5-8.5
PROTEIN TRACE NEG
SPECIFIC GRAVITY 1.029 1.003-1.035
UROBILINOGEN 0.2 <1.0
HPF = high power field
LPF = low power field 75

76. Urinalysis: What Does It All Mean?
How to perform test
•Midstream catch is acceptable
•Should be examined within 2 hours
•Should be refrigerated if not read immediately
76

77. Specific Gravity
• Purpose: urine osmolality and represnts
patients’ hydration status and concentrating
ability of their kidneys
• Normal: 1.003-1.030
• Increased USG: glycosuria, SIADH
• Decreased USG: diuretic use, DI, adrenal
insufficiency, aldosteronism, impaired renal fx
77

78. pH
• Purpose: urinary pH reflects serum pH except
in renal tubular acidosis (RTA), useful for
diagnosis/management of UTIs and calculi
• Normal: 4.5-8.0, slightly acidic usually (5.5-
6.5)
• Alkaline urine: suggest urea-splitting
organism
• Acidic urine: uric acid calculi
78

79. Hematuria
• Criteria: 3 or more RBC per HPF in 2 of 3 urine
samples
• Testing: for peroxidase activity, will be
positive in hematuria, myoglobinuria,
hemoglobinuria
• -if positive: must look at micro to confirm
presence of RBCs
• Types: glomerular, renal, urologic
79

80. Proteinuria
Criteria: >150 mg/day (10-20mg per dL)
-microalbuminuria= 30-150 mg/day (sign of early renal disease)
Normal urinary proteins: albumin, serum globulins, proteins secreted by the nephron
-Dipstick results: 1+ = 30 mg/dL
2+ = 100 mg/dL
3+ = 300 mg/dL
4+ = 1,000 mg/dL
Types: transient and persistent
-Transient: temporary change, benign, self-limited (ex: orthostatic proteinuria that results from
prolonged standing, but negative U/A after recumbency). -Positive test: Repeat U/A
-Persistent has 3 types: glomerular, tubular, overflow
-Glomerular: albumin primary urinary protein
-Tubular: malfunctioning tubule cells
- Overflow: Low MW Proteins overwhelm ability of tubules to reabsorb
-Positive test: Perform 24-hour urinary protein excretion or
spot urinary protein-creatinine ratio
80

81. Glucosuria
• Normal: almost completely reabsorbed in
proximal tubule
• Criteria: occurs at approximately 180-200
mg/dL
• Elevated: DM, Cushing’s syndrome, liver and
pancreatic disease, Fanconi’s syndrome
81

82. Ketonuria
• Normal: not present in urine
• Testing: presence of acetic acid through a
chemical reaction
• Causes: uncontrolled diabetes, pregnancy,
carbohydrate-free diets, starvation
82

83. Nitrites
• Normal: Not present in urine
• Testing: bacteria that reduce urinary nitrates
to nitrites
• -Positive test: can be gram negatives or gram
positive organism (neg > pos)
• (>10,000/mL)Indicates significant number
-Negative test: Can’t R/O UTI because non-
nitrate reducing organism can cause it
83

84. UTIs
• -NOTE: nitrite stick sensitive to air exposure:
after one week of exposure about 1/3 of strips
give false positive
84

85. Leukocyte Esterase
• Testing: presence of neutrophils
• Sterile Pyuria:
• -Organisms: Chlamydia and Ureaplasma
urealyticum
• -Other causes: balantis (inflammed head of
penis), urethritis, TB, bladder tumors, viral
infx, nephrolithiasis (kidney stones), foreign
body, exercise, glomerulonephritis,
corticosteroid use
85

86. Bilirubin
• Normal Bilirubin: no detectable amounts
• -Unconjugated bili: not water soluble, doesn’t
pass through glomerulus
• -Conjugated bili: water soluble, indicates
possible liver dysfunction or biliary
obstruction
86

87. Urobilinogen
• Normal Urobilinogen: only small amounts
• -Urobilinogen: end product of conjugated bili
after metabolized by intestine, small amount
reabsorbed into portal circulation and filtered
by glomerulus
• Increased urobilinogen: hemolysis,
haptocellular disease
• Decreased urobilinogen: antibiotic use, bile
duct obstruction
87

88. 88

89. Fun Facts
• Cat urine, semen, and blood will glow under
fluorescent light.
• So do most other bodily fluids.
• ... anything with phosphorus in it will glow
under a black light.
89

90. FUN URINARY TRACT
DISCUSSION QUESTIONS
Can you drink your own urine?
 Although urine is pretty clean, the exit tube (urethra) is not, so as
it comes out, it gets contaminated like a garden hose with mud
on the tip.
Is it more sanitary to be spit on or peed on?
If you are stranded on a desert island, should you drink
seawater or your own urine?
Why do I have to go to the bathroom immediately after a
cup of coffee?
Why do you have to pee when you hear water dripping?
Does cranberry juice cure urinary tract infections?

Yes, by deforming the disease-causing bacteria
90