regulation of body fluids PH

Question 1

What is metabolic acidosis, how is it caused (give examples of conditions/disease) and how is it compensated for?

Answer 1

• High H+ concertation caused by problems in the kidneys
  
  • e.g. due to chronic diarrhoea
    ○ more HCO3- is being lost instead of reabsorbed so H+ is not buffered
  • Respiratory system increase breathing to remove more CO2 causing the equation to shift to the left. More H+ and HCO3- will react to form carbonic acid which dissociate into CO2 and H2O. CO2 is breathed out. This increases PH.

Question 2

What is metabolic alkalosis, how is it caused (give examples of conditions/disease) and how is it compensated for?

Answer 2

• Low H+ concertation caused by problems in the kidneys
  
  • e.g. due to chronic vomiting
    ○ more H+ is being lost from stomach instead of reabsorbed so HCO3- is not buffered
  • Respiratory system will compensate
  • Respiratory system decreasing breathing to remove less CO2 causing the equation to shift to the right. More CO2 and H2O will react to form carbonic acid which dissociate into H+ and HCO3-. This decreases PH.
  • Respiratory system will kick in faster than the Renal system

Question 3

What is respiratory acidosis, how is it caused (give examples of conditions/disease) and how is it compensated for? In exam

Answer 3

• High H+ concentration due to problem with the lungs e.g. due to
  ○ Hypoventilation
  ○ COPD
  
  • Increase H+, increase HCO3- and increase CO2
  • Compensated for by the kidneys - takes a few days to kick in
  • More common to get acidosis then alkalosis
  • Kidneys will compensate by:
    ○ 1st decrease will be the acidity using HCO3-, haemoglobin and PO3^(2-)
    1. H+ will get filtered out the blood into the filtrate and will not be reabsorbed. Kidneys will secrete H+ into the urine to lower the H+ concertation in the blood and reabsorb HCO3-that was filtered out back into the blood to increase the PH.
    2. There is a limit to how much H+ can put into the urine (max urine PH=4.4) is too acidic the bladder and urethra will be damaged and this will cause pain
    3. Instead of putting H+ straight into the bladder the kidneys will cause H+ to react with HPO4^(2-) to make H2PO4- which will be released into the urine. H2PO4- is valuable in the body (e.g. to make enamel)
    4. So kidneys will stop using HPO4^(2-) and use NH3 instead.
    5. H+ and NH3 react to from NH4- which is secreted into the urine (using NH is better as there are other uses for HPO4^(2-) in the body0
    6. This happens in this order to lower the H+ cocnetaion in the blood
    7. Reaction with HPO4^(2-) and NH3 with H+ will create a HCO3- that will be absorbed into the blood
  • Cause HCO3- to increase further but kidneys don’t care as only H+ controls PH as PH is 5e most important this is way it is compensation not correction

Question 4

What is respiratory alkalosis, how is it caused (give examples of conditions/disease) and how is it compensated for? In exam

Answer 4

• Low H+ concentration due to problem with the lungs e.g. due to
  ○ Hyperventilation
  ○ High altitude
  Decrease H+, decrease HCO3- and decrease CO2
  
  • Compensated for by the kidneys - takes a few days to kick in
  • Kidneys will reabsorb more H+ to buffer the HCO3- and will release more HCO3- into the urine
  • No H+ is need to be excreted so no HPO4(2-) or NH3
  • Cause HCO3- to drop further but kidneys don’t care as only H+ controls PH
  • *

Question 5

What order is the line of defense for acid base change
*

Answer 5

1. 1st decrease will be the acidity using HCO3-, haemoglobin and PO3^(2-)
   
   2. Respiratory compensation
   3. Renal compensation
      a. H+ in urine and HCO3- in blood
      b. PO4^(2-)
      c. NH3