Acid-base balance Flashcards
What is normal PCO2?
40
What is normal pH
7.4
What is normal blood bicarbonate?
25
an acid is an H+ _____
donor
a base is a substance that can
bind a H+
pH is the
negative logarithm of the H+ in mol/L
What is normal blood pH?
7.4
What is normal stomach pH?
1.5
What is normal bile pH?
8
What is normal urine pH?
5-8
What effect does diet have on pH?
protein are metabolized to sulphuric acid
What prevents severe acidosis when we eat meat?
buffers like bicarbonate, monohydrogen phosphate and ammonia
decreasing PCO2 increasing bicarbonate =
increasing pH
increasing PCO2 decreases bicarbonate =
decreases pH
Why is the bicarbonate buffer system so efficient?
because both sides of the equilibrium can be independently regulated
Metabolic acidosis
is low bicarbonate, fixed by decrease CO2
Metabolic alkalosis
high bicarbonate, fixed increase in CO2
Respiratory acidosis
increased CO2, fixed by increase bicarbonate
Respiratory alkalosis
Decrease CO2, fixed by decrease bicarbonate
What happens when bicarbonate buffers acid from proteins?
bicarbonate is changed to CO2 and H2O
Bicarbonate is made
on demand by the kidneys in response to decrease blood pH, and is formed when the acid in the urine is excreted at ammonium and dihydrogen phosphate
Urinary Buffers?
Ammonia and phosphate, ammonia is better because it is made on demand rather than from food
Differences between Ammonium and Ammonia?
Ammonium is a weak acid.
Ammonium does not readily cross cell membranes and blood vessels.
Ammonium concentration increase in a more acid environment in collecting duct lumen and excreted in urine
Ammonia freely diffuses across cell membranes
What is the journey of Ammonium in the nephron?
- ammonium is made in proximal tubule by glutamine
- ammonium is reasorbed in the loop of henle
- ammonia diffuses through medulla
- ammonium trapped by H+ secretion by CD (through ATPase proton pump)
When is Ammonium Excretion Increased?
Metabolic acidosis, respiratory acidosis, higher protein intake, if there is a large acid load, ammonium excretion can increase 5-10 fold but it takes 3-5 days to reach maximum
where is bicarbonate reabsorbed>
proximal tubule
What are the three mechanisms of Metabolic Acidosis?
Addition of an acid not normally present
failure of the kidney to excrete ammonium
loss of sodium bicarbonate through diarrhea
What are acids that can cause metabolic acidosis?
lactic acid (from anaerobic glycolysis, anemia, drugs that interfere with mitochondrial function, shock states, liver failure)
Diabetic ketoacidosis (lack of insulin, fatty acid converting to ketoacids)
Methanol poisining
Ethylene glycol poisoning
Salicylate poisoning
