Acids, Bases, and Buffers

Question 1

Hydrogen Bonding

Answer 1

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)

Question 2

properties associated with Hydrogen Bonding

Answer 2

High Boiling Point = High Heat of Vaporization (same)

High Specific Heat

Question 3

Extracellular Fluid Ion concentration?

Answer 3

High Na+ and Cl- (the ocean! extracellular)

Low K+ and phosphate

Question 4

Intracellular Fluid Ion concentration?

Answer 4

High K+ and phosphate

Low Na+ Cl-

Question 5

Would a strong acid have a high or low Ka?

pKa?

Answer 5

Ka = (H+)(A-)/(HA)
pKa= -logKa = ph

High Ka
Low pKa

Question 6

What is a buffer

Answer 6

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!)

Question 7

Henderson Hasselbalch

Answer 7

ph = pKa + log(conjugate base/Acid)

note: log of 1 = zero

Question 8

ph = pka when?

Answer 8

when the concentration of acid exactly equal the concentration of conjugate base in solution

Question 9

What is the pKa for an acid?

Answer 9

So, the pK for an acid (or any ionizing group) represents that pH at which the two ionic forms are present in equal concentrations

Question 10

Acetate buffering system

CH3COO- + H+

Answer 10

body is usually fighting acidosis so the acetate buffer system is usually accepting protons

Question 11

Principle buffering system in body

Answer 11

Phosphate buffer system (cell)
Bicarbonate buffer system (blood)
Protein buffer system (Hb - blood)
respiratory (bicarb)
Renal (phosphate)

Question 12

An acid buffers best when?

Answer 12

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

Question 13

Bicarbonate buffer system

Answer 13

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

Question 14

How to maintain physiological PH?

Answer 14

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

Question 15

What is the normal pH range of blood?

Answer 15

7.35 – 7.45

Question 16

When are you at risk for Respiratory acidosis?

Answer 16

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

Question 17

What is the result of respiratory acidosis?

Answer 17

increased PCO2 forms:
increased carbonic acid, which breaks down to form:

Increased H+ and Increased HCO3- (so chronically elevated bicarbonate)

Question 18

When are you at risk for Metabolic acidosis?

Answer 18

Anytime H+ is elevated or HCO3- decreases

-ketosis (from poorly controlled diabetes or starvation)
Kidney damage
Chronic diarrhea (loss of bicarb)
excessive lactate production

Question 19

What is the result of metabolic acidosis?

Answer 19

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

Question 20

What causes respiratory alkalosis?

Answer 20

Any factor that decreases PCO2

• hyperventilation
• high altitude

Question 21

So what is the result of excessive CO2 elimination (resp. alkalosis)?

Answer 21

So the Low PCO2, results in less carbonic acid formation, which results in less breakdown, and therefore less H+ and chronically low bicarb

Question 22

Metabolic alkalosis?

Answer 22

Anything that increases bicarb or decreases H+

• excessive ingestion of antacids
• really prolonged vomiting

Question 23

What is the result of metabolic alkalosis?

Answer 23

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

Question 24

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?

Answer 24

It reduces the concentration of CO2 and carbonic acid in the blood, thereby increasing the association of protons with bicarbonate

Question 25

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?

Answer 25

PCO2 decreases and pH increases