module 11 acid base Flashcards
acid-base homeostasis
pH negative logarithm of H+ concentration normal h+: about 40 nml pH: 7.35-7.45 inc pH: few H+ (alkaline) dec. pH: a lot of H+ (acidic) PaCO2: 35-45 HCO3: 22-26
normal cellular metabolism
releases acid (carbonic, metabolic) that must be excreted
3 mechanisms regulate
buffers: chemicals released to balance pH (HCO3 and H+)
respiratory: PaCO2
renal: bicarbonate: HCO3
respiratory regulation
2nd defense
cells continuously make CO2: CO2 + H2O = carbonic acid (H2CO3)
- lung can excrete
Resp. system adjusts amount of H2CO3 in system by altering rate and depth of respirations
- use chemoreceptors
chemoreceptors and regulation
sense CO2, PaO2, pH
- inc. H2CO3 (CO2) -> inc. rate and depth -> inc. removal
- dec. H2CO3 -> dec. rate and depth -> retain CO2
for respiratory regulation to work need
normal
- chemoreceptors
- respiratory neurons
- motor nerves to resp. muscles, diaphragm, chest wall
- airways, lungs, pulm. circulation
PaCO2 indicates
how well resp. system excreting H2CO3
- inc. PaCO2: resp rate and depth insufficient or lung disease prevented excretion
- dec. PaCO2: lungs excreted too much, depth and rate excessive
comensation
respiratory response to any acid imbalance not r/t CO2
- does not correct pH disorder, but compensates by adjusting pH towards normal
- other chemical values made abnormal in process
deficit of any acid except CO2
hypoventilation; retain CO2 (acid) -> dec. pH
excess of any acid except Co2
hyperventilation; blow off CO2 (acid) -> inc. pH
nml HCO3 to H2CO3
20:1 (buffers)
metabolic acidosis
condition leads to excessive acid (not H2CO3) - inc. acid - dec. base - combo s/s: - HA - abd. pain - CNS depression
compensation for metabolic acidosis
hyperventilation ABG: - dec. bicarb: primary imalance - dec. CO2: compensation - pH: low to normal
respiratory acidosis
conditions increased H2CO3 impair resp excretion - impaired gas exchange - inadequate neuromuscular function - impaired resp. control in brainstem
resp. acidosis s/s
HA
inc. HR
cardiac dysrhythmia
neuro abnormalities
respiratory acidosis compensation
inc. renal excretion of metabolic acid, retain HCO3 ABG - CO2: inc: primary imbalance - HCO3: inc. compensation -pH: low to normal
metabolic alkalosis
condition -> dec. of acid (except H2CO3)
- inc. base (HCO3)
- dec. acid
- combo
- over the counter bicarb: antacids
- emesis/ suction
metabolic alkalosis s/s
extracellular fluid depletion that caused it - postural hypoTN hypokalemia - muscle weakness inc. neuromuscular excitability
metabolic alkalosis compensation
hypoventilation: retain H2CO3 ABG: - inc. HCO3: primary imbalance - inc. CO2: compensation - inc. pH
respiratory alkalosis
condition -> dec. H2CO3 - hyperventilation -- hypoxemia -- pain -- psychological distress s/s: neuromuscular excitability
respiratory alkalosis compensation
dec. renal excretion of metabolic acid
-> dec. HCO3 concentration
ABG:
- dec. CO2: primary imbalance
- dec. HCO3: compensation
- inc or normal pH
carbonic anhydrase (bicarbonate buffer system)
HCO3 + H+ -> CO2 + H2O
inc. metabolic acid and bicarb buffer system
inc. metabolic acid (lactic acid): releases H+
- > HCO3 + H+ –(carbonic anhydrase)–> H2CO3: excreted in lungs
dec. metabolic acid and bicard buffer system
dec. metabolic acid -> carbonic acid releasing H+
H2CO3 HCO3 + H+
henderson-hasselbalch equation
pH= pKa + log (HCO3/H2CO3)
pKa: dissociation constant for any particular acid
