Lecture 1/26

• "plasma ultrafiltrate" or urine is waste from the blood indiscriminately filtered through the Bowman's capsule; poisons/wastes are left in filtrate, while nutrients are put back into the body
• water is the main part of urine; acts as a solvent for waste chemicals
• urine is the liquid waste from metabolic processes

  contains urea, organic, and inorganic chemicals dissolved in water
• organic waste in urine - contains carbon/hydrogen; few
• inorganic waste - have ionic/hydrogen bonds (e.g. nitrogen); larger part of filtrate
• anything smaller than albumin isn't filtered out or leaks out
• Reasons we test urine

  • readily available
  • usually easily collected
  • contains information about metabolic processes
  • testing is usualy inexpensive and fairly simple
• testing of urine aids in diagnosis of diseases like diabetes and kidney damage
• testing of urine screens for undetected disease such as enzymes needed for reduction of galactose to glucose
• testing of urine monitors the progression of diseases

  e.g. if diabetic is adhering to dietary restrictions by analyzing kidney deterioration (see albumin in urine)
• testing of urine to monitor certain types of therapy (e.g. drug containing therapies)
• testing of urine to detect certain chemicals (e.g. drugs)
• the renal system

  • 180000 ml plasma filtered each day
  • approximately 99% is reabsorbed
  • major player in blood pressure regulation
• how much reabsorption takes place is dependent on feedback from endocrine system
• the renal pelvis is the "staging area" for ureter
• nephron is the functional unit of the kidney

  ~ 1 million in each kidney

  ~ where filtration takes place

  ~ proximal tubules go down into medulla and get more concentrated

  ~ distal tubules go into cortex
• glomerulus is a knot of porous capillaries
• K+, Na+, NaCl, HCO3- are moved base on acid/base balance. needed
• in the medulla, there is a concentration gradient; as it goes deeper into medulla, interstitial fluid becomes more concentrated with urea and sodium chloride; filtrate is less concentrated than the surrounding tissue, so water is removed from the filtrate
• albumin is repelled (negative charge) by negative charge of podocytes
• Normal urine

  • 1200-1500 ml/day normal void
  • depends on hydration level
  • color: yellow, clear - yellow due to constant release of urochrome pigments
  • urochrome is lipid soluble
• Collection and Testing

  • container - must be clean, sterile, dry, properly labeled with pt name, MR #/DOB, time of collection, date of collection, initials of collection supervisor