R OLES OF THE NEPHRON

S OME F UN F ACTS !!! 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

I F THAT DIDN ’ T HAPPEN …. You’d have to pee once every 3 minutes And drink 1 L of fluids every 10 minutes to maintain Homeostasis!

T HE K IDNEYS ARE THEREFORE … Very efficient at returning stuff back to the blood when needed And removing wastes as needed

U RINE P RODUCTION BY K IDNEYS This happens in 3 main steps: Filtration Reabsorption Secretion

F ILTRATION 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

R EABSORPTION 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.

S ECRETION 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,

S ECRETION CHART Read the paragraph on Secretion and fill in the chart

R EABSORPTION CHART Read through the reabsorption section to fill in the chart This is due MONDAY – April 26

P LASMA F ILTRATE U RINE Plasma, in blood vessels Filtrate, filtered plasma, in nephron Urine, modified filtrate, in collecting tubule

V ENN DIAGRAM P LASMA F ILTRATE U RINE Plasma Filtrate Urine