1. Unit 5 Notes:
The Urinary/Excretory
System

2. (1) Main Organs
• Kidneys
• Ureters
• Bladder
• Urethra

4. (2) Functions
• Filter blood
• Remove impurities, toxins,
excess nutrients
• Reabsorb needed water +
nutrients

5. (3) Kidney Functions
• Excretion of nitrogenous wastes
• Maintain water concentration of
blood
• Maintain electrolyte
concentration of blood
• Regulate blood pH (H ion levels)

6. (4) Ureter, Bladder &
Urethra Function
• Ureters = Tubes which carry filtered
“liquid waste” towards the bladder.
• Bladder = Storage tank for filtered
“liquid waste”.
• Urethra = Tube which allows filtered
“liquid waste” to exit body.

8. (5) Kidneys & Blood Supply
• Kidneys use 20% of body’s blood
• Renal Artery = Entering
oxygenated blood
• Renal Vein = Exiting deox. Blood
• All blood is filtered through
nephrons.

10. (6) Nephrons
• 2 Main Structures:
– Glomerulus  Bundle of capillaries w/
blood to be filtered.
– Renal Tubule  Tubes following
capillaries, which collect filtered contents
• Bowman’s Capsule = Portion of tubule
where initial filtration and absorption
occurs

13. (7) Urine Formation
• Filtration:
– Water + Small Solutes are forced through capillary
walls into Bowman’s Capsule.
• Reabsorption:
– Water, Glucose, Amino Acids & Ions that were filtered
out are actively transported back into capillaries and
blood.
• Secretion:
– H ions, K ions, urea, and drugs/toxins are forced
through capillary walls into renal tubule.

15. (8) Anatomy of Urine
Formation
• Filtration  Bowman’s Capsule of
Renal Tubule
• Reabsorption  Proximal Tube,
Loop of Henle & Distal Tubule of
Renal Tubule
• Secretion  Distal Tubule of Renal
Tubule

17. (9) Nitrogenous Wastes
• Urea: Byproduct of protein
metabolism in the liver.
• Uric Acid: Byproduct of nucleic
acid metabolism.
• Creatinine: Byproduct of creatine
metabolism in muscle tissue.

18. (10) Regulating Drops in
Blood Pressure
• Antidiuretic Hormone (ADH) from Pituitary:
– Increases water reabsorption from renal tubule.
• Aldosterone from Kidney:
– Increases water retention in blood by
reabsorbing more sodium from renal tubule.
• Angiotensin II from Blood:
– Causes vasoconstriction, increasing blood
pressure

19. (11) Don’t Pee It Out…
• Glucose  Chill out on sweets OR Diabetic?!
• Protein  Increased Physical Activity &
Pregnancy OR Hypertension & Nephron
Disease?!
• Pus  Urinary Tract Infection
• Blood  Kidney Stones, Infection, Trauma,
Anemia ?!
• Bile  Liver Disease?!

20. (12) Kidney Dialysis
• Used in hospitals when kidneys fail (stop working)
• Blood is filtered through mechanical pump +
tubing which regulates contents
• Causes for Kidney Failure:
– Repeated kidney infections
– Physical Trauma
– Heavy Metal / Chemical poisoning
– Low Blood delivery (arteriosclerosis)