Unit 5 Notes: The Urinary/Excretory

System

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

(2) Functions• Filter blood•Remove impurities, toxins,

excess nutrients•Reabsorb needed water +

nutrients

(3) Kidney Functions• Excretion of nitrogenous wastes•Maintain water concentration of

blood•Maintain electrolyte

concentration of blood• Regulate blood pH (H ion levels)

(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.

(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.

(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

(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.

(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

(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.

(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

(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?!

(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)