Acid-Base Regulation Flashcards
pH=
pH = -log[H+]
1 numerical change in pH =
10 fold change in the concentration of H+
pH = 7 when H+ and OH- ions are…
equal
1:1 proportion
physiological pH is
7.4
slightly alkaline
acids _____ protons
bases ______ protons
acids donate protons
bases accept protons
strong acids and bases _____ in solution
completely disassociate
HCl and NaOH
weak acids ____ in solution
Donate relatively few of their H+/OH- ions
depending
on Ka (the disassociation constant)
- hight Ka = more disassociation
biological systems involve mostly ____ acids
weak acids
strong acids would be hard to buffer
biological pH fluctuations from 7.4 of ____
+/- 0.5
acidemia
too many H+ ions in the bloodstream
arterial blood pH < 7.35
Acidosis: conditions leading to acidemia
alkalemia
too low H+ ions in the bloodstream
arterial blood pH > 7.45
alkalosis: conditions leading to alkalemia
pH regulation systems
Buffers (1st line of defense, resist change in pH, does NOT remove H+)
Lungs (removed CO2, fast acting)
Kidneys (removed H+, slow acting, can retain HCO3- bicarbonate)
pKa
The pH at which the concentrations of the two components of a
buffer are equal
pKa =
pKa = -log[Ka]
Buffer Chemistry
Henderson-Hasselbalch
pH=pKa + log [A-]/[HA]
bicarbonate buffer
key buffer in the extracellular fluid
phosphate buffer
important in buffering the intracellular fluid and in kidney tubules
proteins (buffer)
have a negative charge that can absorb H+ ions to maintain pH in both extracelular matrix and ICF
histidine side chains
hemoglobin in RBCs
carbonic anhydrase
works on red blood cells to dissolve CO2 into the blood
medulla oblongate
rapidly detects an increase in systematic H+
what does faster/deeper respiration do?
blowing off more CO2
drop in H+
raise pH
what does breathing slower/lighter respiration do?
blow off less CO2
raise H+
lower pH
lungs only deal with ____ acids
volatile acid (carbonic acid/CO2)
volatility = measure of how likely substance is to vaporize
kindeys - buffer
slow acting buffer
deals with non-volatile acids (everything but CO2 and carbonic acid)
retaining HCO3- is main method of increasing pH
excreting/retaining acids to manage pH
respiratory acidosis/alkalosis
changes in the blood CO2 levels (carbonic acid, only volatile acid)
kidneys will try and compensate
metabolic acidosis/alkalosis
changes from all other acids (non-volatile or “fixed”)
lungs will compensate (fast acting) by altering rate/depth of respiration
metabolic acidosis causes and compensations
pH less than 7.37 (too many H+, acidic)
decrease in [bicarbonate]
causes:
- increased non-volatile acids
- loss of excess bicarbonate from body
- kidney failure- decreased H+ secretion and bicarbonate loss
compensations:
- buffering
- increase alveolar ventilation (decreases pCO2 and H+)
- kidneys: increase hydrogen secretion and bicarbonate recovery/synthesis
metabolic alkalosis causes and compensations
pH greater than 7.42 (too few H+, basic)
increase in [bicarbonate]
causes:
- loss of acid due to shallow vomiting (stomach acid is acidic)
- ingestion of excess bicarbonate
- abnormal retention of bicarbonate
compensations:
- buffering
- decreased ventilation (fast-acting): increases CO2 and H+
- kidneys (slow-effect): decreased H+ secretion and bicarbonate recovery/synthesis
respiratory acidosis causes and compensations
pH less than 7.37 (too many H+, low pH)
increase pCO2
causes:
- damage to respiratory organs (lungs, nerves, chest wall)
- damage to respiratory centers of brain (inhibition by drugs/toxins)
compensations:
- kidneys: increase H+ secretion and bicarbonate recovery/synthesis
respiratory alkalosis causes and compensations
pH greater than 7.42 (too few H+, high pH)
decrease pCO2 (hyperventilation)
causes:
- damage to the brain
- stimulants (speed)
- “fainting game” voluntary hyperventilation
compensation:
- Kidneys: decrease H+ secretion and bicarbonate recovery/synthesis
mixed acid-base disorders
heavy vomiting (loss of stomach acid — metabolic alkalosis, increase lactic acid — metabolic acidosis)
Salicylate poisoning (stimulation of respiratory center — respiratory alkalosis, increase of endogenous, non-volatile acids — metabolic acidosis)
7.4 pH
carbonic acid
increase pH
metabolic
bicarbonate
metabolic vs respiratory acidosis/alkalosis
respiratory: volatile acids (blood CO2 levels)
metabolic: non-volatile acids
metabolic or respiratory acidosis or alkalosis:
decreased pH
decrease in blood bicarbonate
kidney failure (decreased H+ secretion)
compensated by increased ventilation
metabolic acidosis
metabolic or respiratory acidosis or alkalosis:
increased pH
increased blood bicarbonate
shallow vomiting
retention of bicarbonate
compensated by decreased ventilation and kidneys decreasing H+ secretion
metabolic alkalosis
metabolic or respiratory acidosis or alkalosis:
decreased pH (acidic)
increased pCO2
damage to lungs or resp. centers of the brain via drugs/toxins
compensated by kidneys increasing H+ secretion
respiratory acidosis
metabolic or respiratory acidosis or alkalosis:
increase pH (basic)
decrease in CO2
damage to brain
stimulants (speed)
voluntary hyperventilation
compensated by kidneys decreasing H+ secretion
respiratory alkalosis
