Acids, Bases, and Buffers Flashcards
Hydrogen Bonding
electrostatic attraction between polar molecules
When an electronegative atom (N,O,F) approaches an H atom that is covalently bound to another electronegative atom (N, O, F)
properties associated with Hydrogen Bonding
High Boiling Point = High Heat of Vaporization (same)
High Specific Heat
Extracellular Fluid Ion concentration?
High Na+ and Cl- (the ocean! extracellular)
Low K+ and phosphate
Intracellular Fluid Ion concentration?
High K+ and phosphate
Low Na+ Cl-
Would a strong acid have a high or low Ka?
pKa?
Ka = (H+)(A-)/(HA) pKa= -logKa = ph
High Ka
Low pKa
What is a buffer
A WEAK ACID plus a some of its CONJUGATE BASE added in
-therefore it is a system that resists changes in ph (until the conjugate base is used up by any acid we added, or the weak acid H protons are used up by base we add to solution!)
Henderson Hasselbalch
ph = pKa + log(conjugate base/Acid)
note: log of 1 = zero
ph = pka when?
when the concentration of acid exactly equal the concentration of conjugate base in solution
What is the pKa for an acid?
So, the pK for an acid (or any ionizing group) represents that pH at which the two ionic forms are present in equal concentrations
Acetate buffering system
CH3COO- + H+
body is usually fighting acidosis so the acetate buffer system is usually accepting protons
Principle buffering system in body
Phosphate buffer system (cell) Bicarbonate buffer system (blood) Protein buffer system (Hb - blood) respiratory (bicarb) Renal (phosphate)
An acid buffers best when?
AT the ph that equals its pka! (because here the acid is split into equal amounts of its weak acid form and conjugate base from)
but generally inside of a 10 to 1 ratio (of acid to con. base or the other way around) it has buffering properties
Bicarbonate buffer system
our body likes to maintain a ration of 20/1 (bicarb to carbonic acid) - 6.1 operating pka
But this gets fucked up when there is to much acid around the bicarb must bind that acid (ratio drops). htis creates too much carbonic acid, but we can breath this acid off as CO2
How to maintain physiological PH?
Respiratory responses – controlling PCO2 and [H2CO3] in plasma and acting via the bicarbonate buffer system
Renal responses – controlling excretions of acids and bases in urine and acting, in part, via the bicarbonate buffer system
What is the normal pH range of blood?
7.35 – 7.45
When are you at risk for Respiratory acidosis?
When respiration is impaired in anyway! (inadequate CO2 elimination)
=pneumonia, emphysema, severe asthma, acute pulmonary edema, congestive heart failure, drugs that inhibit respiratory centers
-because CO2 accumulates and dissolves in the blood to form carbonic acid
What is the result of respiratory acidosis?
increased PCO2 forms:
increased carbonic acid, which breaks down to form:
Increased H+ and Increased HCO3- (so chronically elevated bicarbonate)
When are you at risk for Metabolic acidosis?
Anytime H+ is elevated or HCO3- decreases
-ketosis (from poorly controlled diabetes or starvation)
Kidney damage
Chronic diarrhea (loss of bicarb)
excessive lactate production
What is the result of metabolic acidosis?
Increased H+, which requires bicarb to bind it up, so bicarb decreases! Then CO2 combines with water to form carbonic acid, which breaks down to H+ and bicarb (to replace the bicarb)
-so we use a lot of CO2 and CO2 becomes chronically low
What causes respiratory alkalosis?
Any factor that decreases PCO2
- hyperventilation
- high altitude
So what is the result of excessive CO2 elimination (resp. alkalosis)?
So the Low PCO2, results in less carbonic acid formation, which results in less breakdown, and therefore less H+ and chronically low bicarb
Metabolic alkalosis?
Anything that increases bicarb or decreases H+
- excessive ingestion of antacids
- really prolonged vomiting
What is the result of metabolic alkalosis?
the decreased H+ causes more CO2 retention (PCO2 is chronically increased) so that we can used it to form carbonic acid, which breaks down to replace the H+, but also increases bicarb
A 19-year-old male with type I diabetes fails to administer his insulin, thus causing the onset of diabetic ketoacidosis. This results in deep and rapid breathing (Kussmaul breathing). Which of the following best describes how the increased breathing acts to compensate for (i.e. correct) the acidosis?
It reduces the concentration of CO2 and carbonic acid in the blood, thereby increasing the association of protons with bicarbonate
A medical student becomes extremely anxious during a Biochemistry examination and begins to hyperventilate uncontrollably. What initial effects does the hyperventilation have on the student’s PCO2 and blood pH?
PCO2 decreases and pH increases
