Renal Regulation of Acid/Base Balance Flashcards
What is the principle of acid-base balance?
input=output
whatever you put in must go out
What are the 5 points of entry for acids and bases?
- De novo from metabolism
- Processing of digested foods
- GI tract from digestion
- Metabolism of stored fat and glycogen
- Kidneys
What is a buffer?
a buffer is solution that prevents large changes in pH after the addition or loss of protons from external sources
What is the dominant buffer int the ECF?
Bicarbonate-HCO3-
What is the dominant buffer int the ECF?
Bicarbonate-HCO3-
Co2 + H20—H2Co3
What is the dominant buffer of the ICF?
Phosphates
Protein
more fluid in ICF then ECF
What is acidosis? When a patient has what are the 2 possible causes to choose betwen? and how do you know which it is?
decrease in pH; Increase [H+]
caused by:
-increase in proton conc.-change in ion gap
-loss in base–no change in ion gap
What is alkalosis?
increase in PH; decrease [H+]
Caused by:
-Base gain
-decrease proton concentration
What 2 structures within what structure in the kidney handle acids and bases?
- Proximal Tubule
-reabsorb an enormous amount of bicarb - Distal Tubule
-secrete H+ or bicarb(always reabsorbed first) to balance net output
Both are structure throughout/within the nephron
How do we move/buffer fluid between ECF and ICF?
K/H exchanger
Acidosis: H+ into cell/K+out of cell
Alkolosis: H+ out cell/K+ in cell
What happens when we keep CO2 in the body? (i.e holding breath, low ventilation)
Increase Co2
Increases [H+]
decrease PH
What is the mechanism of Na/H+ exchanger bicarb reabsorption in the distal tubule?
Use an Na/H+ anti-porter-apical membrane that pumps H+ out into lumen– H+ combines with HCO3 to form H2CO3—broken down to water and CO2—Bicarbonate is gone
Na/HCO3 symporter on basolateral membrane
Pumps HCO3 and pumps it back out into the blood—New Bicarb
What happens when increase ventilation?
Decrease Co2
Decrease [H+]
Increase PH
What hormone increases sodium reabsorption through the Na/H exchanger?
Angiotensin II
What are the two cells are found in the distal tubule?
- Principle
2. Intercalated Cells
What are two types of intercalated cells?
- Type 1 -alpha
2. Type 2- active in alkaosis
What is the mechanism of Cl-/HCO3- ?
same mechanism except for Cl being symported together with
What are the two types of reabsorption transports in the proximal tubule?
- Na/H exchanger
2. Cl- Transporter
What are 2 types transport mechanism for bicarbonate reabsorption in the in the distal tubule?
- K/ ATPase
2.
What is the mechanism of bicarbonate reabsorption of Type A of distal tubule?
H/K ATPase
—-H2CO3 —breaks down into—HCO3 + H=
What are the two responses to excess acid in the blood?
- HPO4—
2. Amonium
What is base load?
excrete base,
excrete bicarb intercalated cells
What happens in an acid load ?
excess acid
- get rid of acid
- replace lost bicarb with new bicarb
What is the mechanism of bicarb formation via titratable acids?
K/H+ exchanger
pumps out H+ combine w/HPO4 and excreted in lumen and HCO3 is resborbed back into interstium
Where does the generation of titratable acids occur?
Proximal tubule
What is the process of ammonium formation?
catabolism of protein—creation of glutamine— glutamine taken up in the distal tubule–glutamine is converted NH4+ +HCO3—NH4+ secreted into lumen; bicarb exits into interstium
How do we quantify how much new bicarb has been made by the kidneys?
NAE =TA+NH4-HCO3
Where do we secrete bicarb?
distal tubule
What are 4 factors that can cause acidosis?
- Acid gain
- Decreased respiration
- keto-acids
- base loss diarrhea
What are 4 factors that can cause acidosis?
- decreased respiration
- keto-acids
- renal failure
- base loss diarrhea
What causes the formation of keto-acids?
alternate fuel soource
Ketone bodies, seen in diabetes
What are 4 factors that can cause acidosis?
- decreased respiration/ventilation
- keto-acids
- renal failure
- base loss diarrhea
What is the anion gap equation?
AG=Na-HCO3
Normal between 8-12
What is the point of testing the anion gap?
it allows you to determine acid again or base loss in the body.
if you have acid gain A-, it will increase the u
What is the point of testing the anion gap?
it allows you to determine acid again or base loss in the body.
if you have acid gain A-, it will increase the unknown anions in the plasma, therby increasing the gap
if it is a base loss anion gap will stay the same
Why will anion gap stay the same when there is a base loss?
chloride will replace the lost bicarbonate
What causes alkalosis?
- Lose acid
2. Gain base
What are the 4 ways a patient can develop alkalosis?
- hyperventilation
- vomitting
- bicarb overdose
4.
What are the 4 ways a patient can develop alkalosis?
- hyperventilation
- vomitting
- bicarb overdose
- chronic dieuretic usage
