1. TAKE NOTES! Excretory System (Urinary System)
Excretion, kidneys, and urine….

2. Excretory System
EXCRETION: is the process that rids body of metabolic wastes.
MAIN PARTS:
Kidneys
Ureter (urine to bladder)
Urethra (bladder to outside)
renal veins/ arteries
bladder

3. Basic Information
URINE FORMATION: YOU MAKE ABOUT 1 mL OF URINE PER MINUTE!
Urine is made by tiny little filtering units called Nephrons
WHAT GETS REABSORBED?:
most water, nutrients,
some salts (Na+, Cl-)
WHAT DOESN’T GET REABSORBED:
some water, wastes,
excess salts

4. Kidneys do not just make urine, they also regulate the blood pH
How does your body know when you have to go pee?
NEURONS!!

5. Nervous System Involvement for Urination
Stretch receptors in the bladder detect stretch  message sent to brain  response sent to muscles to contract to empty bladder  message sent back to brain that bladder has been empties, stops muscle contraction

6. Nervous System Involvement for regulating blood pH
If blood is too acidic:
H+ ions detected  message sent to brain  response sent to kidneys to excrete more H+ ions  blood pH increase (less acidic)  message sent to brain to send message to kidneys to stop excreting H+ ions