Unit 3 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) 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.

(4) Nephrons• The nephrons are the filtering units inside the

kidneys.

• 2 Main Structures:– Glomerulus Bundle of capillaries w/ blood to be

filtered.

– Renal Tubule Tubes following capillaries, which collect filtered contents• Bowman’s CapsulePortion of tubule where initial

filtration and absorption occurs

(5) Urine Formation Steps1- Filtration: – Water + Small Solutes are forced through capillary walls

into Bowman’s Capsule.

2- Reabsorption:– Water, Glucose, Amino Acids & Ions that were filtered

out are actively transported back into capillaries and blood.

3- Secretion:– H ions, K ions, urea, and drugs/toxins are forced through

capillary walls into renal tubule.

(6) 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.

(7) 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)