acid-base Flashcards
pH and [H+]
inversely related
increase [H+], decrease pH (acidotic) - donate H+
decrease [H+], increase pH (alkalotic) - accept H+, give up OH-
strong acids vs. weak acids
strong: dissociate completely in soln
weak: dissociate partially
hydrogen functions
maintain cell membranes
helps with enzyme activity
component of H2O and keeps body hydrated
helps in energy production
hydrogen is a component of
sugars, proteins, starch, fats
where is the most acidic place in the body? why?
stomach bc HCl acid
*if HCl out of stomach - major damage
*duodenum has defense mechanisms to neutralize acid
*LES prevents movement of gastric acid into esophagus
what does acid-base balance affect?
electrolytes (Na, K, Cl)
hormones
oxygen transport and delivery
oxyhemoglobin dissociation curve
measures Hgb O2 saturation % (Y axis) to O2 partial pressure mmHg (x axis)
the human body can function for a short period of time out of what pH range before it becomes incompatible with life? survivable range?
pH < 6.8 or > 7.8 –> incompatible
7.2 -7.5 –> survivable
2 types of acids in the body
volatile and non-volatile acids
volatile acids
can be converted to gas
excreted by lungs
*carbonic acid (H2CO3)
*CO2 + H2O <–> H2CO3
non-volatile acids
cannot be converted to gas
excreted by kidneys
*phosphoric acid
*sulfuric acid
*acetoacetic acid
*beta-hydroxybutyric acid
*LACTIC ACID metabolized by body (liver + kidney)
buffers
chemicals in body that combine with acid or base to change pH
accept or release a H+
almost instantaneous, but short-lived
3 main buffer systems
- bicarbonate - carbonic acid buffer
- phosphate buffer
- protein buffers (Hgb)
bicarbonate
main ECF buffer
byproduct of cellular metabolism
combines with H2O = carbonic acid
in lungs: H2O + CO2
in kidneys: H + HCO3
what breaks down carbonic acid
carbonic anhydrase
^in many tissues of the body (esp. lungs+kidneys)
lungs
H2O + CO2
kindeys
H + HCO3
phosphate buffer
main ICF buffer
protein buffers
- carboxyl group (COOH) - weak acid, gives up H+
*amino acid
*acetic acid - amino group (NH2) - accept H+
*amino acids: carboxyl + amino group
*ammonia (NH3) - Hgb: picks up CO2 at cellular level
when H+ concentration increases…
pH decreases (acidic)
H+ moves INTO cells
more + charged ions IN cell
K+ moves OUT of cell
^electrical neutrality is restored inside cell
respiratory mechanisms
body produces CO2
CO2 + H2O = carbonic acid
exhaling excretes carbonic acid
^doesnt affect non-volatile acids (lactic acid)
how can the body pH be adjusted?
changing rate and depth of breathing
acidotic: increase rate/depth to blow off more CO2
alkalotic: decrease rate/depth to hold onto CO2
kidney excretion
can eliminate large amounts of acid (NOT carbonic acid)
can excrete bicarbonate
can conserve/produce bicarb ions
if kidneys fail, pH balance fails - depends on normal functions of renal system (because aren’t excreting H+ or base)
what is the most effective regulator of pH
kidneys
rates of correction
buffer: instantaneously
respiratory mechanisms: several minutes to hours
renal mechanisms: hours to days
respiratory compensation
if underlying problem is METABOLIC, hyperventilation or hypoventilation can help
metabolic compensation
if underlying problem is RESPIRATORY, renal mechanisms can bring about met compensation
patho of acidosis: disturbed to homeostasis
disturbed
decrease pH/acidosis
stimulates brain and arterial receptors
increase RR
decrease CO2
decrease H2CO3 (carbonic acid)
increase pH
restored
patho of alkalosis: disturbed to homeostasis
disturbed
increase pH/acidosis
stimulates brain and arterial receptors
decrease RR
increase CO2
increase H2CO3 (carbonic acid)
decrease pH
restored
hyperventilation vs. hypoventilation
lungs are primary controller of H2CO3 –> CO2 is carried in blood to lungs –> in lungs, mixes with H2O and forms carbonic acid
hyper = CO2 blown off (increases pH)
hypo = CO2 retained (decreases pH)
blood buffer system responds in
seconds
lungs are primary controller of
H2CO3 - carbonic acid
CO2 carried from blood to lungs, then mixed with H2O to form carbonic acid
kidneys are primary controller of
HCO3 - bicarbonate
adjust the amount of bicarb that is:
*reabsorbed in bloodstream
*excreted in urine
if blood is too acidic, kidneys will…
if blood is too alkaline, kidneys will…
acid: reabsorb bicarb
alkaline: excrete bicarb
