Lecture 8 Flashcards
What is the kidneys purpose?
Excrete waste products
Retain desirable solutes
Maintain pH
Maintain osmolality -> maintain BP
Glomerulus
filters larger particles: cells and Albumin
Small particles continue for possible reabsorption or excretion
Proximal Convoluted Tubules
“pumps”, by active transport, most solutes back into the blood
Loop of Henle
reabsorption of H2O
increasing osmotic pressure along the loop -> causes H2O to be reabsorbed
Makes urine more concentrated
Distal Convoluted Tubule
final adjustments of electrolytes and acid/base by HCO3-1
Collecting Ducts
also reabsorbs more water
Glomerular Filtration Rate
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”
Renal Threshold
the maximum rate that it can be reabsorbed
When can’t substances be reabsorbed in Proximal Convoluted Tubules?
When substances have concentrations larger than the RT
Urea
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
Blood Urea Nitrogen (BUN)
Largest N containing component of blood besides protein
Produced in breakdown of amino acids
Azotemia
High levels of urea
Pre-renal azotemia
Reduced renal blood flow
High protein diets
Protein catabolism
Protein catabolism
proteins -> amino acids -> urea + carbohydrates
Performed when energy stores are low
Renal azotemia
kidney failure
Post-renal azotemia
obstruction of urine flow, out of kidneys
Creatine phosphate
an energy source like ATP
CP + ATP lasts for about 10 seconds of activity
Where is creatine created?
The liver
arginine + lysine + methionine -> creatine
What happens when creatine is transported to cells?
Becomes Creatine Phosphate
When the phosphate is removed from Creatine Phosphate what happens?
CP becomes creatinine
What is done with Creatinine?
Excreted into plasma
Filtered through kidneys
Diagnostic Value Creatinine
High serum or low urine levels = kidney not removing creatinine
reflects problems with glomerular function
BUN/Creatinine ratio normal range
10-20 mg/dL
