acid-base imbalance Flashcards
pH
potential or power of H
scale of acidicty/bascidity
H ion []
negative logarithm
high = basic (low H, accept H or give up OH)
low = acidic (high H, donate)
strong acid
dissociate completely
weak acid
dissociate partially
normal bodily pH
7.35 - 7.45
serum
not same everywhere
stomach pH
HCl
would cause damage outside of stomach
duodenum has defense mechanism to minimize
LES prevents esophageal entering
mucous cells secrete mucus and bicarb to neutralize
hydrogen
component of cell membranes, enzyme activity, H2O and keeps body hydrated, E production
component of sugar, protein, starch, fat
pH and bodily function
can function for short time outside of homeostatic range
<6.8 and >7.8 incompatible with life
enzymes function in narrow range
can cause electrolyte imbalances (Na, K, Cl)
can affect hormones
O2 transport and delivery -> oxyhemoglobin dissociation curve: acidic = hgb release, basic = hgb hang on (prefer acidic)
volatile acids
convert to gas, excrete/eliminated by lungs, carbonic acid = H2CO3
H2CO3 = H2O + CO2
non volatile acids
dont dissolve
lactic, phosphoric, sulfuric, acetoacetic, beta hydroxybutyric
eliminated by kidney (except lactic)
skeletal muscle pH
6.9 - 7.2
bone pH
7.4
liver pH
7.2
pleural fluid pH
7.6
lactic acid
anaerobic metabolism
metabolized by liver and kidney
reconverted if O2 present in tissue, then used for E
phosphoric acid
bones and kidney function, Ca
sulfuric acid
protein metabolism
acetoacetic acid
liver
beta hydroxybutyric
increase with exercise, cal restriction, fasting, and ketoacidosis (dx DKA)
cause of pH change
body produces more acids than bases: ingest in food/drink, met of lipids and protein, cell met waste = CO2 (volatile)
more difficult to correct alkaline -> avoid alkalosis esp if ill
homeostasis
buffers: constant and immediate
resp: fast but short (min - hrs)
renal: last to action, long term, hours - days
buffers
chm in body that combine with acid or base to change pH
accept or release H, almost instantaneous, short lived - not sustainable
3 main systems: bicarbonate, phosphate, protein
buffers: bicarbonate
carbonic acid buffer
CO2 is byproduct of cellular met, combine with H2O in serum to form carbonic acid, carbonic anhydrase breaks down into carbonic acid
lungs = H2O + CO2 (breathe out)
kidneys = H+ + HCO3- (kidneys excrete)
buffers: phosphate
main intracellular -> cant measure
buffers: protein
most proteins have buffer function
carboxyl (COOH) = weak acid -> give up H: amino acid, acetic acid
amino group (NH2-) -> accept H: amino acid have both, ammonia (NH3)
hgb picks up CO2 at cellular level -> more that is attached = less avail to create carbonic acid
buffers - cellular compensation
cells like neutral charge
H+ and K+, K+ is mostly inside
acidic: H+ goes inside cell and K comes out (hyperK)
temporary correction -> will reverse when pH normal again
but if kidneys are working -> will excrete excess K
respiratory compensation
body produces CO2, CO2 + H2O = H2CO3 (occurs in lungs, and H2CO3 found in blood), exhale to excrete H2CO3 (lungs are primary controller)
doesnt affect fixed acids (non volatile) -> lactic
body pH can be adjusted by changing rate and depth of breathing: acidic = deeper, alkalotic = shallow
kidney compensation
adjust HCO3 (bicarb), harder to excrete than reabs (kidneys better with acidotic)
eliminate large amounts of acid except carbonic, can also excrete base, can conserve (reabs) and produce new bicarb ions
most effective -> if kidneys fail, pH balance fails
acidosis: increase bicarb reabs, increase H excretion in urine
alkalosis: decrease bicarb reabs, decrease H excretion in urine
compensation
complete = return to normal
partial = outside norm still but compensation occurring
metabolic issue = hypervent or hypovent can lead to resp compensation
resp issue = renal mechanisms can lead to metabolic compensation
