pH and Water Flashcards
Exam 1
Water’s function in biological systems
Reactant/Product in many metabolic/enzymatic rxns
Solubilizes buffers (like bicarbonate that remain physiological pH), proteins, and other important biologically important molecules
Stabilizes and preserves protein structure (especially globular)
Participates in H-bonding, aiding in solubility of molecules
Excellent Nu
Most abundant cellular component, comprising 60-70% adult lean body mass (more in infants, less in old age)
Total body water is a function of…
Age, body mass, & body fat
Important sources of acid in the body are…
carbonic acid, phosphoric acid
Henderson-Hasselbalch equation
pH=pka+log[A-]/[HA]
Buffer systems used in body…
combination of weak acid or base and its conj. base or acid - resists pH changes
bicarbonate, regulated through lungs hypo/hyper ventilation and renal control
phosphate, which can also be regulated through renal control
Importance of bicarbonate buffer system in regulating blood pH
It has a volatile acid component: CO2
This allows regulation by increasing or decreasing the ratio of CO2 to the conj. base, allows pH to be influenced by lungs and renal system
Respiratory influence on acid-base balance
respond within minutes to disturbances by hyperventilation to increase pH or hypoventilation to decrease pH
Hyperventilation
CO2 is eliminated, raising the ratio of conj. base to acid and increasing pH
Hypoventilation
CO2 is retained, lowering the ratio of conj. base to acid and decreasing pH
Isohydric transport
transport of CO2 without generating change in blood pH
transported as HCO3- or on the terminal amino group of Hb
when generated by catabolic reactions, it’s turned into HCO3- and carried into the lungs via RBCs (Cl- exchange allows it to be passed in and out of the RBCs), where its transferred back to CO2 and expelled
How does Hb contribute to CO2 transport?
carries CO2 on the terminal amino group as a carbamate
Acidosis
pH<7.35, caused by diabetic ketosis
lungs would be hypoventilated (would respond by hyperventilation)
kidneys would be excreting HCO3- and retaining H+ (would respond by retaining or generating HCO3-, or oxidative deamination of amino acids)
Alkalosis
pH>7.45, may follow vomiting of acidic gastric contents
lungs would be hyperventilated (would respond by hypoventilation)
kidneys would be retaining HCO3- (reabsorbing in lumen) and excreting H+ (would respond by retaining H+)
Kidney has the ability to…
[excrete H+ & retain HCO3- to increase pH
reabsorb HCO3- in lumen
oxidative deamination of amino acids]
[retain H+ & excrete HCO3- to decrease pH]
slow - hours to days
What buffer is best?
pka closest to desired pH with highest equal molar conc. of components
