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© 2009 The McGraw-Hill Companies, Inc. All rights reserved
The Urinary System PowerPoint® presentation to accompany:
Medical Assisting Third Edition
Booth, Whicker, Wyman, Pugh, Thompson
© 2009 The McGraw-Hill Companies, Inc. All rights reserved
30-2
Learning Outcomes
30.1 Describe the structure, location, and functions of the kidney.
30.2 Define the term nephron and describe its structure.
30.3 Explain how nephrons filter blood and form urine.
30.4 List substances normally found in urine.
© 2009 The McGraw-Hill Companies, Inc. All rights reserved
30-3
Learning Outcomes (cont.)
30.5 Describe the locations, structures, and functions of the ureters, bladder, and urethra.
30.6 Explain how urination is controlled.
30.7 Describe the causes, signs and symptoms, and treatments of various diseases and disorders of the urinary system.
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30-4
Introduction
Kidneys
Ureters
Bladder
Urethra
System functions to remove waste products from the blood
Main functional units of the kidneys are the nephrons
Nephrons filter the blood and form the urine
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30-5
The Kidneys
Functions
Remove metabolic waste products from the blood
Secrete the hormone erythropoietin, which stimulates
bone marrow to produce red blood cells
Secrete the hormone renin, which helps regulate blood
pressure
Description
The kidneys are bean-shaped organs that lie behind the
peritoneal cavity (retroperitoneal) on either side of the
vertebral column.
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30-6
Renal sinus – concave depression of the
surface of the kidney
Hilum – point of entry for the renal artery,
renal vein, and ureter
Renal pelvis – expansion of the ureter that
further divides into calyces
The Kidneys (cont.)
Kidney
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30-7
Renal cortex – outermost portion of the kidney that covers the pyramids and dips down between them
Renal medulla – middle portion that also divides into renal pyramids
Renal column – portion of the cortex between pyramids
The Kidneys (cont.)
Kidney
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30-9
The Kidneys: Nephrons
Renal
Corpuscles
Composed of a group of capillaries
called a glomerulus
Glomerulus is surrounded by
Bowman’s capsule
Blood filtration occurs in corpuscle
Removes waste products from the blood
Each kidney contains about 1 million nephrons
Made of a renal corpuscle and a renal tubule
Extend from the Bowman’s
capsule of a nephron
Consist of three parts:
Proximal convoluted tubule
Loop of Henle
Distal convoluted tubule
Glomerulus
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30-11
The Kidneys – Nephrons (cont.)
Veins of the Kidney
Afferent Arteriole
Glomerulus
Efferent Arteriole
Peritubular Capillaries
Afferent arterioles deliver
blood to the glomeruli
Efferent arterioles carry
blood from the glomeruli to
peritubular capillaries
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30-12
Apply Your Knowledge
What are the functions of the kidney?
ANSWER: The kidney removes metabolic waste products
from the blood, secretes erythropoietin to help regulate RBC
production, and secretes renin to help regulate the BP.
Correct!
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30-13
Urine Formation: Glomerular Filtration
First process occurs in renal
corpuscles
Fluid part of the blood is
forced from glomerulous into
Bowman’s capsule
Becomes glomerular filtrate
Glomerulus
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Factors affecting glomerular filtration
Filtration pressure – amount of pressure
that forces filtrate from the glomerulus into
Bowman’s capsule.
Determined by blood pressure
Rate of filtration – sympathetic nervous
system control
Constriction of afferent arterioles decreases
filtration pressure
Urine Formation: Glomerular Filtration (cont.)
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30-15
Second process in urine formation
Glomerular filtrate proximal convoluted tubule
Nutrients, water, and ions pass through the walls of the
renal tubule into the peritubular capillaries
Water reabsorption depends on hormones
Antidiuretic hormone (ADH)
Aldosterone
Both increase water reabsorption, which decreases urine
production
Urine Formation: Tubular Reabsorption
Tubular
Reabsorption
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30-16
Urine Formation: Tubular Secretion
Third process of
urine formation
Substances move
from blood in the
peritubular
capillaries into the
renal tubules
Secreted substances
Drugs
Hydrogen ions
Waste products
Tubular
Secretion
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30-18
Urine composition Mostly water
Urea and uric acid
Formed by the breakdown of proteins and nucleic acids
Trace amounts of amino acids and various ions
Secretion of waste products helps maintain the acid-base balance
Urine Formation (cont.)
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30-19
Apply Your Knowledge
Match the following:
___ Second process in urine formation A. Glomerular filtration
___ Substances move from blood into renal tubules B. Tubular reabsorption
___ Depends on filtration pressure C. Tubular secretion
___ Third process of urine formation
___ First process of urine formation
___ Filtrate flows into the proximal convoluted tubule
C
C
B
A
A
B
ANSWER:
Nice Job!
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30-21
Ureters, Urinary Bladder, and Urethra (cont.)
Urinary bladder
Expandable muscular organ
Stores up to 600 ml urine on average
Detrusor muscle – smooth muscle in wall of bladder
Trigone – triangle on internal floor of bladder formed by
urethra and ureters
Micturation
Process of urination
Stretching of bladder triggers process
Approximately 150cc of urine
Bladder
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30-22
Impulses to contract urethra; inhibit micturition impulse until ready to urinate
Urination
External urethral
sphincter relaxes
Micturation reflex –
impulses from pons
and hypothalamus
Detrusor muscle
contracts
Urine expelled
Bladder
distends
Stretch receptors
Spinal cord
Parasympathetic nerves stimulate detrusor muscle
Brain stem
and
cerebral
cortex
Ureters, Urinary Bladder, and Urethra (cont.)
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30-23
Urethra
Tube that moves urine from the bladder to the
outside world
Shorter in females – patient education
Urinate when urge occurs
Drink adequate clear fluids
Wipe front to back
Urinate after intercourse
Ureters, Urinary Bladder, and Urethra (cont.)
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30-24
True or False:
___ Ureters move urine by peristalsis.
___ The detrusor is formed by the openings of the ureters and urethra.
___ The process of micturition is triggered when the bladder contains about
150 ml urine.
___ The urethra move urine from the kidney to the bladder.
___ The urethra is longer in females.
___ Contraction of the detrusor muscle pushes urine from the bladder.
Apply Your Knowledge
F
F
T
F
T
trigone
males
ureters
T
ANSWER:
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30-25
Diseases and Disorders of the Urinary System
Disease/Disorder Description
Acute renal failure Sudden loss of kidney function; may be
reversible with treatment
Chronic renal
failure
Kidneys slowly use ability to function; not
reversible
Cystitis Urinary bladder infection; more common in
females
Glomerulonephritis Inflammation of the glomeruli of the kidney;
one cause of chronic renal failure
Incontinence Inability to control urination
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30-26
Disease/Disorder Description
Polycystic kidney
disease
Enlargement of kidneys because of the
presence of many cysts within them; slow,
progressive disease
Pyelonephritis Complicated urinary tract infection; starts
with a bladder infection and spreads to both
kidneys; can be acute or chronic
Renal calculi Kidney stones; can become lodged in ducts
within kidneys or ureters
Diseases and Disorders of the Urinary System
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30-27
Apply Your Knowledge
Matching:
___ Complicated urinary tract infection A. Pyelonephritis
___ Inability to control urination B. Glomerulonephritis
___ Kidney stones C. Incontinence
___ Slow loss of kidney function D. Chronic renal failure
___ Bladder infection E. Renal calculi
___ Inflammation of the glomeruli F. Cystitis
___ Kidney enlargement due to cysts G. Acute renal failure
___ Sudden loss of kidney function H. Polycystic kidney disease
H
G
F
E
D
C
B
A
ANSWER:
GOOD JOB!
© 2009 The McGraw-Hill Companies, Inc. All rights reserved
30-28
In Summary
The organs of the urinary system include the
kidneys, ureters, bladder, and urethra
The kidneys remove metabolic waste products from
the blood and secrete erythropoietin and renin
Urine travels through the ureters to the bladder
Stretching of the bladder triggers micturition reflex
Urine travels from the bladder through the urethra to
the outside world
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30-29
This too shall pass—just like a kidney stone.
~H. Madson