Lecture 8

Excrete waste products Retain desirable solutes Maintain pH Maintain osmolality -> maintain BP

filters larger particles: cells and Albumin Small particles continue for possible reabsorption or excretion

“pumps”, by active transport, most solutes back into the blood

reabsorption of H2O increasing osmotic pressure along the loop -> causes H2O to be reabsorbed Makes urine more concentrated

final adjustments of electrolytes and acid/base by HCO3-1

also reabsorbs more water

1500 mL/min of blood into: 125 mL/min (Small stuff continues on to be further “filtered” ) 1375 mL/min returned to circulation with the “big stuff”

the maximum rate that it can be reabsorbed

When substances have concentrations larger than the RT

dominant waste product found in urine the form of N from amino acids that are degraded ~ 50% gets reabsorbed by the tubules- the rest is reabsorbed

Largest N containing component of blood besides protein Produced in breakdown of amino acids

High levels of urea

Reduced renal blood flow High protein diets Protein catabolism

proteins -> amino acids -> urea + carbohydrates Performed when energy stores are low

kidney failure

obstruction of urine flow, out of kidneys

an energy source like ATP CP + ATP lasts for about 10 seconds of activity

The liver arginine + lysine + methionine -> creatine

Becomes Creatine Phosphate

CP becomes creatinine

Excreted into plasma Filtered through kidneys

High serum or low urine levels = kidney not removing creatinine reflects problems with glomerular function

10-20 mg/dL