medical student

1. The Urinary System
Dr. Jhood Abdul Samad

2. Functions of the Urinary System
Slide
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
 Elimination of waste products
Nitrogenous wastes
Toxins
Drugs

3. Functions of the Urinary System
Slide
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
 Regulate homeostasis
Water balance
Electrolytes
Acid-base balance in the blood
Blood pressure
Red blood cell production
Activation of vitamin D

4. Organs of the Urinary system
Slide 15.2
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
 Kidneys
 Ureters
 Urinary bladder
 Urethra
Figure 15.1a

5. Anatomy of kidneys
The kidneys are a pair of bean-shaped
organs found along the posterior wall of
the abdominal cavity. The left kidney is
located slightly higher than the right
kidney because of the liver .

6. Kidneys weigh about 150 g in the male
and about 135 g in the female. They are
typically 10-12 cm in length, 5-7 cm in
width, and 2-3 cm in thickness

7. Location of the Kidneys
Slide 15.3
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
 At the level of T12 to L3
• A top each kidney is an adrenal gland the
most important hormones secreted by the
adrenal cortex are cortisol, aldosterone,
(essential for balancing salt and water in
the body) adrenaline and noradrenaline
are secreted by adrenal medulla .

8. • The blood supply to the kidneys arises
from the paired renal arteries, branches
from abdominal aorta and out of each
kidney renal vein.

9. Regions of the Kidney
Slide 15.5
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
 cortex – outer
region
 medulla – inside
the cortex
 pelvis – inner
collecting tube
Figure 15.2b

10. Nephrons
Slide 15.8
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
 The structural and functional units of the
kidneys
 Responsible for forming urine
 Main structures of the nephrons
Glomerulus
Renal tubule

11. Glomerulus
Slide
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
 A specialized
capillary bed
 Attached to
arterioles on both
sides (maintains
high pressure)
Large afferent
arteriole
Narrow efferent
arteriole Figure 15.3c

12. Renal Tubule
Slide
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
 Glomerular
(Bowman’s)
capsule
 Proximal
convoluted
tubule
 Loop of Henle
 Distal
convoluted
tubule
Figure 15.3b

13. Urine Formation Processes
Slide
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
 Filtration
 Reabsorption
 Secretion
Figure 15.4

14. Filtration
Slide
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
 Water and solutes smaller than proteins
are forced through capillary walls
 Blood cells cannot pass out to the
capillaries
 Filtrate is collected in the glomerular
capsule and leaves via the renal tubule

15. Reabsorption
Slide
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
 The peritubular capillaries reabsorb several
materials
 Some water
 Glucose
 Amino acids
 Ions
 Most reabsorption occurs in the proximal
convoluted tubule

16. Materials Not Reabsorbed
Slide
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
 Nitrogenous waste products
Urea
Uric acid
Creatinine
 Excess water

17. Secretion – Reabsorption in
Reverse
Slide
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
 Some materials move from the
peritubular capillaries into the renal
tubules
Hydrogen and potassium ions
Creatinine
 Materials left in the renal tubule move
toward the ureter

18. Ureters
Slide
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
 Slender tubes ( approximately 20-30 cm
long) attaching the kidney to the bladder
Continuous with the renal pelvis
Enter the posterior aspect of the bladder
 Runs behind the peritoneum

19. Urinary Bladder
Slide
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
 Smooth, collapsible, muscular sac
 Temporarily stores urine
Figure 15.6

20. Urinary Bladder
Slide
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
 Trigone – three openings
Two from the ureters
One to the urethrea
Figure 15.6

21. Urethra
Slide
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
 Thin-walled tube that carries urine from
the bladder to the outside of the body by
peristalsis
 Release of urine is controlled by two
sphincters
Internal urethral sphincter (involuntary)
External urethral sphincter (voluntary)

22. Ureteric stones
 Causes:
• Unknown reasons
• Inadequate urinary drainage
• Presence of infected urine
• Hypercalcaemia

23.  The presence of an impacted ureteric is
characterized by:
• Haematuria
• Agonizing colicky pain (ureteric colic),
which radiates from loin to groin

24. Micturition (Voiding)
Slide
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
 Both sphincter muscles must open to
allow voiding
The internal urethral sphincter is relaxed
after stretching of the bladder
Activation is from an impulse sent to the
spinal cord and then back via the pelvic
splanchnic nerves
The external urethral sphincter must be
voluntarily relaxed

25. Maintaining Water Balance
Slide
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
 Water intake must equal water output
 Sources for water intake
 Ingested foods and fluids
 Water produced from metabolic processes
 Sources for water output
 Vaporization out of the lungs
 Lost in perspiration
 Leaves the body in the feces
 Urine production

26. Maintaining Acid-Base Balance in
Blood
Slide
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
 Blood pH must remain between 7.35
and 7.45 to maintain homeostasis
Alkalosis – pH above 7.45
Acidosis – pH below 7.35

27. Question
• The right kidney is slightly lower
because ________.
• it is displaced by the liver
• it is displace by the heart
• it is slightly smaller
• it needs protection of the lower ribs