Kidneys and Excretion

  1. Kidneys purpose
    • extract metabolic wastes
    • retains needed/wanted parts of fluids
    • maintain blood pH
    • juggle bicarbonate, nitrogen, acids, bases ions
    • maintain water balance
    • removes wastes from the body, especially nitrogenous wastes
  2. importance of the liver
    • deamination: process of breaking down amino acids into elements, separating nitrogen specifically
    • byproduct is ammonia 
    • ammonia is broken down to urea (a less toxic form), similar to bicarbonate from carbonic acid
    • uric acid is formed from breakdown of nucleic acids
    • urea and uric acid removed at kidney (nephron)
  3. Nephron
    • workhouse of excretory system
    • quantity: one million per kidney, so 2 million total in body
    • different arterioles supply nephron with blood
    • (Afferent arteriole) branch into arteriole ball called the glomerulus
    • surrounded by a funnel-like structure called Bowman's capsule (strainer)
    • everything in your blood goes into your glomerulus
    • Bowman's capsule filters out water in blood, amino acids, glucose, everything in plasma basically
    • RBC, WBC, and platelets are left behind
    • (Efferent arteriole) RBC, WBC, platelets sent back into circulatory system
  4. Uric acid
    • insoluble
    • in excess, it will precipitate and seep out into interstitial space and form crystals in joints (gout)
  5. Ureter
    from kidney to bladder passageway
  6. Sphincter
    controls pee flow
  7. Renal
    to do with kidneys
  8. Proximal tubule
    • first site after Bowman's capsule
  9. Collecting duct
    • collects all the urine
    • several nephrons are connected to one collecting duct
    • multiple collecting ducts per kidney
  10. Filtration
    • first step
    • separates large proteins from plasma
    • from glomerulus to Bowman's capsule
  11. Glomerular filtrate
    • product that is filtered from glomerulus
    • made up of anything in plasma, therefore it is basically just plasma
  12. Reabsorption
    • occurs mainly in proximal tubules and loop of Henle
    • taking back what your body wants from what would otherwise be disposed of
  13. Secretion
    • happens in distal tubules and collecting ducts
    • secretion of waste from capillaries into nephron
    • "last chance"
    • mostly happens in distal tubules
  14. Filtration process
    • blood enters glomerulus under very high pressure
    • substances that are too large do NOT enter Bowman's capsule
  15. Reabsorption process
    • Na+ is pumped back into blood until threshold
    • Cl and HCO3 follow to balance the charge
    • H20 follows to maintain salt concentration homeostasis
    • Urine is concentrated
  16. Secretion
    • other wastes are secreted into distal tubules by active transport and leave the body via urine
    • this is why urine is tested for drugs
    • collecting duct, distal tubule are also where antidiuretic hormone (ADH) acts to increase water reabsorption and where H+ can be relocated to control acidity
    • ADH increases permeability to water
  17. Loop of Henle
    reabsorbs water, sodium
  18. ADH
  19. Aldosterone
    water, sodium, chlorine
  20. Diabetes mellitus
    • caused by inadequate levels of insulin
    • blood sugar levels rise
    • excess sugar remains in nephrons
    • water follows glucose, too much water is disposed of
    • solution: islet cell transplant, insulin injection
  21. Diabetes insipidus
    cannot reabsorb water
  22. Bright's disease (nephritis)
    • holes in filter allow blood to pass, so you wee blood
    • could be caused by trauma, muscle atrophy, etc
  23. Kidney stones
    precipitation of minerals
  24. Dialysis
    filtering using machine instead of kidney
  25. Hemodialysis
    • hooked up to a box, blood goes through tube into box to filter blood
    • chemicals are used to attract waste products, also diffusion used
  26. Peritoneal dialysis
    fluid is pumped into peritoneal space (space around kidney inside of thoracic cavity)
Card Set
Kidneys and Excretion