1. Ch. 17 – Urinary System

3. Urinary System - Structures
Pair of kidneys
Pair of ureters
Transport urine away from the kidney
Urinary bladder
Urine reservoir
Urethra
Conveys urine to
the outside of the
body

5. Kidney – General Functions
Filters blood to produce urine
Remove substances from the blood
Regulate metabolic processes

6. Kidneys - General Characteristics
Reddish brown in color
Bean shaped
Smooth surface
Renal capsule
Tough fibrous capsule surrounding the kidney

7. Kidneys - Location Either side of vertebral column
Left higher than the right
Positioned retroperitoneal
Behind parietal peritoneum
Posterior wall of abdominal cavity
Near back muscles in a depression
Adipose and connective tissue
Hold kidneys in place

8. Kidneys - Structure Lateral side (convex) Medial side (concave)
Medial depression (hilum) leads to renal sinus (hollow chamber)
Two distinct regions
Renal medulla
Renal cortex

10. Kidneys - Functions Remove & excrete metabolic waste from blood
Secretes erythropoietin for blood cell formation
Use of renin
Regulates blood pressure
Regulate volume, composition, and pH of body fluids
Leads to formation of urine

11. Renal Disease Kidney transplant Result of end stage renal disease
Hemodialysis
Peritoneal dialysis

12. Renal Disease

13. Kidney Vessels Renal arteries Renal veins Supply kidneys with blood
Enters at the hilum
Renal veins
Carries blood from the kidneys back to the heart

14. Nephrons “Functional unit of the kidney” Loop of Henle
Contain renal tubule and renal corpuscle
Loop of Henle
Increase SA & efficiency of the kidney
Regulate water and electrolyte balances
Filtering of blood occurs due to pressure (filtration)
End product is urine

15. Nephrons Renal corpuscle Urine formation: Composed of a glomerulus
Cluster of blood capillaries
Surrounded by a glomerular capsule
Urine formation:
1. Glomerular filtration
2. Tubular reabsorption
3. Tubular secretion

16. Urine Formation – 1. Glomerular Filtration
Water and dissolved substances are filtered out of the glomerulus
Glomerular filtrate
Mostly water and large protein molecules

17. Rate of Filtration Related to pressure 125 mL/minute
180,000 mL/24 hours (~45 gallons)
Most of the fluid is reabsorbed into the plasma
Glomerulonephritis
Typically caused by immune response
Shock
Result of blood pressure dropping
Causes pressure in glomerulus to drop

18. Regulation of Filtration
Increases when excess fluid is present
Decreases when fluid needs to be conserved
Renin
Enzyme that acts with angiotensinogen to eventually form angiotensin II
Angiotensin II maintains sodium and water balances and blood pressure

19. Urine Formation – 2. Tubular Reabsorption
Substances are transported out of the filtrate and back into the blood
Glucose, H2O, amino acids, albumin
Role of Na+ in transport of negative ions
Chloride, phosphate, bicarbonate
Glucosuria
Glucose in the urine

20. Glucosuria

21. Regulation of Urine Concentration
Aldosterone
Hormone that stimulates additional reabsorption of sodium & water
ADH (antidiuretic hormone)
Released when concentration of water in the blood decreases
Water retaining hormone

22. Renin – Aldosterone - ADH

23. Urine Formation – 3. Tubular Secretion
Certain substances leave the plasma and enter the renal tubule
Increases some urinary excretions

24. Urine Content Dependent on diet and exercise
95% water, urea, uric acid, amino acids, electrolytes
Uric acid
Nucleic acid catabolism
10% excreted
Gout
Urea
Amino acid catabolism
50% reabsorbed

25. 0.6 - 2.5 liters/day Volume influenced by: Urine Production
Fluid intake
Environmental and body temperature
Emotional condition
Respiratory rate

26. Micturition Process that expels urine from the bladder… Peeing!
Detrusor muscle contracts
External urethral sphincter relaxes
Made of skeletal muscle
Micturition Reflex Center
Triggered by distension of the bladder
Located in the spinal cord

27. Micturition 150 mL 300 mL 600 mL Automatic bladder
Triggers urge to urinate
300 mL
Sensation of fullness intensifies
600 mL
Maximum before pain receptors activated
Automatic bladder
Loss of voluntary control over urination

28. Micturition Disorders
Polyuria
Excess production of urine
Oliguria
Scanty amounts of urine
Anuria
Absence of urine

29. Kidney Disorders Kidney Stones
Formed from uric acid, calcium, or magnesium
Found in the collecting ducts and renal pelvis
Pain from ureter stretching
60% pass on their own
Sound waves can be used to break them down
Lithotripsy

30. Kidney Stones

31. Cystitis Disorders Bladder infection More common in females
Why?
Bacterial or from residual urine