(406) patho - acid / base Flashcards
(36 cards)
pH
the potential or power of hydrogen
the negative logarithm of the hydrogen ion -> when H+ goes up, pH goes down
acid substances can “” an H+ ion & alkaline substances can “” an H+ ion and “” an OH-
give ; accept ; give up
why is hydrogen important to the body
-helps maintain cell membranes
-helps w/ enzyme activity
-component of H2O
-helps energy production
hydrogen is a component of
sugars
proteins
starch
fats
what does a neutral acid-base balance mean
-pH=7
-equal H+ & OH-
pH goal range
7.35 - 7.45
pH is not the same through the body
what happens if the body’s pH is not within goal range
-enzymes malfunction
-electrolyte imbalances (esp K+)
-O2 transport & delivery can be affected
if the body is more acidic, hemoglobin will
give up oxygen more readily at the tissue
if the body is more alkalotic, hemoglobin will
hold on to the oxygen and not give it to the tissue
a bigger problem then if the pt is more acidic
what pH is incompatible to life
below 6.8 d/t profound effect on cellular metabolism, enzyme activity and oxygen delivery to the tissue
if the pH is above 7.8
life threatening -> disrupts essential bodily functions, particularly in the cardiovascular and nervous system
what are the two types of acids in the body
volatile & non volatile
volatile acids
-can be converted to gas
-excreted/eliminated by the lungs
-one volatile acid in body (carbonic acid H2CO3 -> H2O + CO2)
allows lungs to expel carbon dioxide
non volatile acids
-lactic acid (met by kid/liv, can be reconverted & used as energy production if needed)
-phosphoric acid (bones & kidney support)
-sulfuric acid (produced w/ protein met)
-acetoacetic acid (produced in liver)
-beta hydroxybutric (inc w/ exercise, calorie restrictions, fasting & dx of ketoacidosis)
will all be eliminated by kidney (expect lactic acid) & cannot be converted to a gas
lactic acid is a byproduct of what
anaerobic metabolism
at baseline, does the body produce more acids or bases
acids b/c we eat/drink more acidic foods, the metabolism of lipids & protein generate acids and cellular metabolism waste product is CO2 which makes volatile acid
how does the body maintain acid - base homeostasis
-buffers: works all the time & is immediate
-respiratory system: rapid but short lived
-renal system: long term balance
buffers
-chemicals in the body that combine w/ acid or bases to change the pH
-accept or release a H+
-almost instantaneous but short lived
3 main systems: bicarbonate - carbonic acid buffer, phosphate buffer & protein buffers (hemoglobin)
Bicarbonate - Carbonic Acid
-main buffer seen outside the cell in the ECF
-carbonic anhydrase breaks down carbonic acid, if in the lungs this allows for CO2 to be expelled & if it is in the kidneys then will break down into H+ + HCO3- and the kidneys can excrete the hydrogen ions
if a patient is in the ICU and is acidic & not compensating, what can we give
sodium bicarb to raise their pH
Bicarbonate - Carbonic Acid equation (need to know)
HCO3- (bicarb) + H+ <-> H2CO3 (carbonic acid)<-> CO2 + H2O
if we retain CO2, equation will work in the direction of increases bicarb (think COPD or resp depression
kidneys can generate bicard & rid H+, lungs can expel CO2
phosphate buffer
main intracellular buffer
H+ +HPO4-2 = H2PO4- (example of buffer picking up a H+ ion intracellularly to balance pH)
Protein Buffers
-nearly all proteins can function as buffers
-carboxyl group (COOH) is a weak acid that gives up H+ (ex: amino acids & acetic acid)
-amino group (NH2-) accept H+
-hemoglobin picks up CO2 at the cellular level which results in less CO2 to make carbonic acid
cellular compensation
pH decreases -> H+ move into the cell creating more positively charged ions in the cell -> K+ moves out of the cell to maintain a neutral charge since it is also a + ion -> electrical neutrality is restored inside the cell
process will reverse as pH neutralizes & H+ will move out of the cell and K+ will move back into the cell
