4.02 Understand the Functions and
Disorders of the Urinary System
4.02 Understand the functions and disorders of
the urinary system
Essential Questions
• What are the functions of the urinary system?
• What are some disorders of the urinary system?
• How are disorders of the urinary system treated?
• How do you relate the body’s hormone control to the
urinary system?
4.02 Understand the functions and disorders of the urinary system
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Understand the functions of
the urinary system
Functions:
• Filtration
• Excretion
• Formation of urine
• Fluid and electrolyte balance
• Elimination of urine
4.02 Understand the functions and disorders of the urinary system
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4.02 Understand the functions and disorders of the
urinary system
• Filtration: The filtering of the blood to create
a filtrate.
– This is the first step in urine formation
– Filtrate contains various substances
– These substances are either reabsorbed back into
the bloodstream, or excreted from the body as
urine.
4.02 Understand the functions and disorders
of the urinary system
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Understand the functions of
the urinary system
Excretion
• What is excretion? Removal of waste matter from the
body
• Why does the body have excretory functions?
• What is the composition of wastes excreted by the
urinary system?
– Nitrogenous wastes
– Salt
– Water
4.02 Understand the functions and disorders of the urinary system
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Understand the functions of
the urinary system
Filtration
•To form urine the
nephron must perform
three processes:
•Glomerular
filtration
•Tubular
reabsorption
•Tubular secretion
Reabsorption
Secretion
4.02 Understand the functions and disorders of the urinary system
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• Blood from renal
artery enters
glomerulus
• High pressure in
glomerulus forces fluid
into Bowman’s
capsule, where it is
filtered
4.02 Understand the functions and disorders of the urinary system
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BOWMAN’S CAPSULE
– A tuft of capillaries
• Bowman’s capsule filters out 125cc of fluid/min.
…how many cc’s per hour is this?
• As the filtrate continues through the tubules, 99% of
water is reabsorbed back into the blood stream
4.02 Understand the functions and disorders of the urinary system
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Reabsorption
•
What substances are reabsorbed?
–
–
–
–
–
–
–
•
•
Water
Glucose
Amino acids
Vitamins
Bicarbonate ions
Sodium
Potassium
If blood levels of certain substances are high, the substances will not be
reabsorbed.
Threshold: the term used to describe the limit of reabsorption
4.02 Understand the functions and disorders of the urinary system
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Secretion
•What is secretion?
•The transport of substances
from the blood into the urine in
the distal and collecting
tubules.
•It is the opposite of
absorption.
4.02 Understand the functions and disorders of the urinary system
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• What substances are secreted into the
collecting tubules?
–
–
–
–
–
Some medications
Ammonia
Creatinine
Hydrogen ions
potassium
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Understand the functions of
the urinary system
Fluid and electrolyte balance
• Electrolytes are selectively secreted to maintain
body’s acid-base balance.
– What are electrolytes? Electrically charged particles
– What do they do? Help determine fluid and acid-base
balance
4.02 Understand the functions and disorders of the urinary system
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Understand the functions of
the urinary system
Fluid and electrolyte balance
Chemical control
– ADH (Anti-diuretic hormone)- secreted by the posterior pituitary
–
gland when blood pressure decreases
Aldosterone- A steroid secreted by the adrenal cortex when plasma
sodium decreases or plasma potassium increases.
Nervous control
– Directly through the action of nerve impulses on the blood vessels leading to the
kidney
– Indirect nerve control is through stimulation of certain endocrine glands whose
hormone secretion will control urinary secretion.
4.02 Understand the functions and disorders of the urinary system
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Understand the functions of
the urinary system
Fluid and electrolyte balance
Chemical control
• The amount of ADH produced is related to the
level of body hydration
4.02 Understand the functions and disorders of the urinary system
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Understand the functions of
the urinary system
Forming more dilute urine:
Define “dilute urine”
• What are diuretics?
• What effect do they have on the production of
urine?
• Give examples of substances that have diuretic
effects.
4.02 Understand the functions and disorders of the urinary system
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Understand the functions of
the urinary system
Fluid and electrolyte balance
What effect does this cycle have on your blood pressure?
4.02 Understand the functions and disorders of the urinary system
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Understand the functions of the urinary system
The flow of electrolytes
Review urine formation, electrolyte exchange,
and some factors that effect urine volume.
4.02 Understand the functions and disorders of the urinary system
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Understand the functions of
the urinary system
• What do you predict will happen to blood pressure
when the blood volume increases?
• What if blood
volume decreases?
4.02 Understand the functions and disorders of the urinary system
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Understand the functions of
the urinary system
• If more water is reabsorbed back into the body--what will happen to urine concentration?
• (more or less concentrated?)
4.02 Understand the functions and disorders of the urinary system
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Understand the functions of
the urinary system
Elimination of urine
What causes the bladder to empty?
–The bladder can hold about 500 ml of fluid
–When it fills, the stretch triggers urination-emptying the bladder
Is this a voluntary or involuntary action?
What can prevent urination? Internal and external sphincters
4.02 Understand the functions and disorders of the urinary system
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Understand the functions of
the urinary system
Elimination of urine
Urinary output
Average urinary output = 1500 ml per day
*How many ounces is this?
What effects
the color of
your urine?
4.02 Understand the functions and disorders of the urinary system
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Urinalysis
An examination of urine
• What does normal urine look like?
• What constitutes an abnormal urinalysis?
4.02 Understand the functions and disorders of the urinary system
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Urinalysis
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Urinalysis
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Urinalysis
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Disorders of the urinary
system
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Disorders of the urinary system
Cystitis
• What is cystitis
(cyst= medical term for ____ +itis =___ )
– Inflammation of the mucous membrane lining of the bladder
• Most common cause: E. Coli
• What are the major symptoms of cystitis?
– Painful urination (dysuria)
– Frequent urination (polyuria)
4.02 Understand the functions and disorders of the urinary system
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Disorders of the urinary system
Cystitis
• More common in females―Why ??
– The urethra is shorter in females
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Disorders of the urinary system
Glomerulonephritis
Disease which injures
the glomerulus.
What does this mean for
my health?
• When the filter is damaged, blood cells and
blood proteins enter the filtrate
• Removal of waste products is decreased
• Electrolyte balance is abnormal
• Kidney damage can occur
4.02 Understand the functions and disorders of the urinary system
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Disorders of the urinary system
Glomerulonephritis
• Two types:
– Acute- can occur in children after a bacterial infection, usually strep
throat
– Chronic- Occurs when the filtration membrane has been
permanently affected. May result in kidney failure.
4.02 Understand the functions and disorders of the urinary system
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Disorders of the urinary system
Renal calculi
Also known as nephrolithiasis
nephro lith iasis
What are renal calculi made of?
–Calcium phosphate
–Uric acid
What are the symptoms?
–Extreme pain
–Nausea and vomiting
–Burning when urinating
–Hematuria 4.02 Understand the functions and disorders of the urinary system
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Disorders of the urinary system
Renal calculi
• What will happen if the
ureters are blocked?
– The renal pelvis and calyces
become enlarged due to
excess fluid
4.02 Understand the functions and disorders of the urinary system
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Disorders of the urinary system
Renal calculi
• How is it treated?
– Increase fluids
– Medications
– Lithotripsy
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Disorders of the urinary system
Renal calculi
• How does lithotripsy work?
– Shockwaves are created outside the body that travel through until the
waves hit the dense stones.
• Is it a cure?
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Disorders of the urinary system
Renal failure
• Acute
• What causes it?
–
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–
–
–
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Nephritis
shock
Injury
Bleeding
Heart failure
Poisoning
– What are the symptoms?
• Oliguria- diminished production of urine
• Anuria- absence of urine
• Uremia- when the blood retains urinary waste products
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Disorders of the urinary system
Renal failure
chronic
• Symptoms may be none in early stages, urinalysis may
reveal proteinuria
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Disorders of the urinary system
Renal Failure
• Chronic kidney
disease leads to a
buildup of fluid and
waste products in
the body.
4.02 Understand the functions and disorders of the urinary system
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Disorders of the urinary system
Renal Failure
• How is it treated?
– Peritoneal dialysis
• Read about it! Page 587
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Disorders of the urinary system
Renal Failure
• How is it treated?
– Hemodialysis
• Read about it! Page 587
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Disorders of the urinary system
Renal Failure
• Compare the treatment of acute and
chronic renal failure.
4.02 Understand the functions and disorders of the urinary system
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Disorders of the urinary system
How does hemodialysis mimic
glomerular function?
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Disorders of the urinary system
Renal transplant
• What is involved in this treatment option?
• When does a patient get a transplant?
• Read about it! Page 588
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Disorders of the urinary system
Renal transplant
What is the
major
complication of
renal
transplantation?
4.02 Understand the functions and disorders of the urinary system
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4.02 Understand the functions and disorders of
the urinary system
• Essential Questions
• What are the functions of the urinary system?
• What are some disorders of the urinary system?
• How are disorders of the urinary system treated?
• How do you relate the body’s hormone control to the
urinary system?
4.02 Understand the functions and disorders of the urinary system
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