1. The Urinary System Chapter 30 Medical Assisting
PowerPoint® presentation to accompany:
Medical Assisting
Third Edition
Booth, Whicker, Wyman, Pugh, Thompson

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.

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.

4. Urinary System Organs 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

5. The Kidneys Functions Description
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.

6. The Kidneys (cont.)
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
Kidney

7. The Kidneys (cont.)
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
Kidney

8. Previous

9. The Kidneys: Nephrons 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
Renal
Tubules
Renal
Corpuscles
Composed of a group of capillaries called a glomerulus
Glomerulus is surrounded by Bowman’s capsule
Blood filtration occurs in corpuscle
Glomerulus

10. Previous

11. The Kidneys – Nephrons (cont.)
Blood Flow Through Nephron
Afferent Arteriole
Afferent arterioles deliver blood to the glomeruli
Efferent arterioles carry blood from the glomeruli to peritubular capillaries
Glomerulus
Efferent Arteriole
Peritubular Capillaries
Veins of the Kidney

12. Correct! 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!

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

14. Urine Formation: Glomerular Filtration (cont.)
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

15. Urine Formation: Tubular Reabsorption
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
Tubular Reabsorption

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

17. Tubular Reabsorption
Tubular Secretion
Previous

18. Urine Formation (cont.)
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

19. Nice Job! Apply Your Knowledge ANSWER: 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 B
ANSWER: C A C
Nice Job! A B

20. Ureters, Urinary Bladder, and Urethra
The Ureters
Long muscular tubes
Carry urine to the bladder
Peristalsis – rhythmic muscular contraction of ureters
Previous

21. Ureters, Urinary Bladder, and Urethra (cont.)
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

22. Ureters, Urinary Bladder, and Urethra (cont.)
Urination
External urethral sphincter relaxes
Micturation reflex – impulses from pons and hypothalamus
Detrusor muscle contracts
Urine expelled
Brain stem and cerebral cortex
Impulses to contract urethra; inhibit micturition impulse until ready to urinate
Spinal cord
Parasympathetic nerves stimulate detrusor muscle
Bladder distends
Stretch receptors

23. Ureters, Urinary Bladder, and Urethra (cont.)
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

24. Apply Your Knowledge Impressive! ANSWER: T 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 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.
Impressive!
trigone F T
ureters F F
males T

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

26. Diseases and Disorders of the Urinary System
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

27. Apply Your Knowledge GOOD JOB! ANSWER: 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 A
ANSWER:
GOOD JOB! C E D F B H G

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

29. End of Chapter 30 This too shall pass—just like a kidney stone.
~H. Madson