ROLES OF THE NEPHRON
SOME FUN FACTS !!!

120 ml of blood filtered by the kidney each minute!

Only 1 ml of the 120 ml actually made into urine

Your bladder can collect from 300 to 400 ml of urine
before you have to take a *tinkle*

119 ml of filtered fluid (called FILTRATE) is moved
back into the blood
IF THAT DIDN’T HAPPEN….
 You’d
 And
have to pee once every 3 minutes
drink 1 L of fluids every 10 minutes
to maintain Homeostasis!
THE KIDNEYS ARE THEREFORE…
 Very
efficient at returning stuff back to
the blood when needed
 And
removing wastes as needed
URINE PRODUCTION BY KIDNEYS
 This
happens in 3 main steps:


Filtration
Reabsorption

Secretion
FILTRATION

Blood enters glomerulus under high pressure

Pressure causes 20% of blood plasma (120 ml of 600
ml) to be forced into the Bowman’s Capsule

Water, salt, glucose, amino acids and urea (good
stuff and bad stuff all pass through into BC

Blood Cells and proteins don’t enter the BC – too
large to exit the capillaries

Filtrate – ISOTONIC to PLASMA
REABSORPTION

The “wanted” stuff or “good stuff” that filters
into the nephron is then reabsorbed back to the
blood

Good stuff includes salts, glucose, amino acids

Reabsorption takes place in the regions of the
Proximal and Distal Convoluted Tubules.
SECRETION

Non useful wastes and toxins are ACTIVELY
TRANSPORTED from the blood into the nephron

This “BAD STUFF” is “fast tracked” into the
PCT, DCT, and CT of the nephron

Things like extra H+ ions, extra OH-, extra
glucose, ammonia, drugs,
SECRETION CHART

Read the paragraph on Secretion and fill in the
chart
REABSORPTION CHART


Read through the reabsorption section to fill in
the chart
This is due MONDAY – April 26
PLASMA
FILTRATE
URINE
Urine,
modified
filtrate, in
collecting
tubule
Plasma, in
blood vessels
Filtrate, filtered
plasma, in
nephron
VENN DIAGRAM
PLASMA
FILTRATE
Plasma
URINE
Filtrate
Urine