ANP 1107 Final exam

• Filtrate at top of ascending loop


  To dilute, due to salt removal
• Collecting duct in the absence of ADH


  Remains impermeable to water and very dilute urine is produced
• Lowest osmolality of urine can be 100 mOsm
• Concentrated urine


  Formed when you are dehydrated
• ADH


  Acts at the collecting duct, increases number of water channels in principle cells
• Collecting ducts extend into the medullary area of the kidneys
• Facilitative: water reabsorption


  Regulated and variable based on the body's needs
• If we are hydrated, can lead to a decrease in osmolality, and our urine concentration can be as low as 100mOsm
• When we are dehydrated, large amount of ADH are secreted, osmolality will rise to up to 1200mOsm
• With almost max levels of ADH being secreted, almost 99% of water can be reabsorbed from filtrate, and is returned to blood. Only 1/2 a liter per day of highly concentrated urine is excreted
• Diuretics


  Enhance the output of urine, any substance not reabsorbed
• Alcohol inhibits the release of ADH
• Most diuretics inhibit Na+ reabsorption
• Renal Clearance

  The volume of plasma from which the kidneys clear a particular substance in each time (usually one minute)
• Equation is RC=UV/P and is measure in ml/min
• Urine composition


  95% water and other 5% is solute
• Highest concentration solute=urea
• Other nitrogenous wastes found in urine

  • uric acid (from the metabolism of nuclei acids)
  • creatinine (from the muscles)
• Solutes in decreasing order

  • urea
  • Na+
  • K+
  • phosphate
  • sulfate
  • creatinine
  • uric acid
• If higher than normal amount of any solute found in urine, or presence of glucose or proteins leads to/indicates pathology
• Other solutes present in variable amounts

  • Ca+
  • Mg+
  • HCO3-
• Fresh urine


  A clear and pale to deep yellow colour
• Yellow colour of urine

  Comes from urochrome which is from the destroying of hemoglobin
• Cloudy urine can indicate a UTI
• A more concentrated urine means that is a deeper colour
• Fresh urine


  Has a slight smell but if urine is led to stand it begins to smell like ammonia. This is because the breaking down of urea
• Some drugs and veggies alter the smell of urine
• People with diabetes also can have a slight fruity smell to their urine
• pH of urine


  Usually about 6, and can vary due to metabolism and diet of anywhere from 4.5-8
• A diet rich in proteins and whole wheats leads to acidic urine
• Diet rich in veggies leads to alkaline urine
• Specific gravity of urine

  From 1.001-1.035 and depends solute concentration
• Micturition


  The process of urination
• Things that must happen for micturition

  • 1.) Detrusor must contract
  • 2.) Internal urethral sphincter must open
  • 3.) External urethral sphincter must open
• Detrusor and internal sphincter


  Smooth muscles that are innervated by the PNS and SNS, and you cannot voluntarily control them
• External urethral sphincter


  Skeletal muscle, that you can control, is voluntary
• Urinary incontinence


  The inability to control your urination. This is caused by weakened pelvic floor muscles, pressure from pregnancy, or nervous system problems
• Stress incontinence


  Sudden increase in intra-abdominal pressure (coughing or laughing) forces urine through the external urethral sphincter
• Urinary retention


  When the bladder is unable to get rid of its contained urine, often caused by general anaesthesia, and in men
• Renal failure


  Caused by not enough functioning nephrons, and this causes filtration to be reduced or stopped