Biochemical Buffers And Regulation Of Body PH

Question 1

Tissue pH

Answer 1

7.40

Question 2

Organs that have role in regulating pH

Answer 2

Lungs and kidneys

Question 3

PH equation

Answer 3

pH = -log10 [H+]

Question 4

Change in one pH unit represents _____ change in [H+]

Answer 4

10-fold change

Question 5

T/f strong acids and bases ionize completely in dilute aqueous solutions

Answer 5

T

Question 6

Degree of dissociation of weak acid depends on ____

Answer 6

Value for Ka

Question 7

Weak acids in body

Answer 7

. Amino acids
. Fatty acids
. Lactic acid
. Ammonium

Question 8

Weak bases in body

Answer 8

. Lactate
. Acetate
. Ammonia

Question 9

Henderson-Hasselbalch equation

Answer 9

pH = pKa + log ([A-]/[HA])

Question 10

What is a buffer

Answer 10

. Solution that resists a change in pH when either acid or base is added
. Mixture of weak acid and conjugate base

Question 11

When does a buffer work best and why?

Answer 11

. Composed of equal amts of HA and A-

. Any added strong base can combine w/ weak acid and be neutralized and vice versa

Question 12

When do you lose buffering power?

Answer 12

. Depleted conjugate acid or conjugate base

Question 13

Smallest changes in pH occur with a buffer when ___

Answer 13

Addition of acid/base to a buffer whose pH is in the region of the pK

Question 14

When [HA] = [A-] then pH = ____

Answer 14

pK

Question 15

Best buffering range for conjugate pair

Answer 15

.pK +/- 1pH unit

Question 16

Why is pH regulation important to our health

Answer 16

. Enzymes and proteins function in specific pH ranges

Question 17

Acceptable range pH for arterial plasma pH and consistent range w/ life

Answer 17

. Acceptable: 7.40 +/- 0.05

. Life: 6.8-7.8

Question 18

Sources of acids and bases in body

Answer 18

. Glucose and fatty acid oxidation generate CO2 and H2O

. Metabolism generates organic acids

Question 19

Primary buffer system in body

Answer 19

Bicarbonate

Question 20

Bicarbonate equation

Answer 20

CO2 (gas) -> CO2 (dissolved) + H2O H2CO3 H + HCO3

Question 21

Important players in bicarbonate buffer system

Answer 21

. carbonic acid (H2CO3)
. Bicarbonate/base (HCO3-)
. CO2 acid

Question 22

K1 in bicarbonate rxn

Answer 22

[H2CO3]/[CO2][H2O}

Question 23

K2 in bicarbonate rxn

Answer 23

[H+][HCO3-]/[H2CO3]

Question 24

How is bicarbonate rxn K1 equilibrium maintained?

Answer 24

Carbonic anhydrase

Question 25

WHen bicarbonate rxn K1 lies to the left there’s more ___

Answer 25

CO2 than H20 (400 times more)

Question 26

When K2 lies to the right in bicarbonate rxn there mor e____

Answer 26

HCO3, not much H2CO3

Question 27

Final equation for find bicarbonate pH

Answer 27

pH = 6.1 + log ([HCO3]/[CO2])

Question 28

How does buffer w/ pK of 6.1 act as effective buffer at pH 7.4?

Answer 28

Open system and acid and base can be added/substrate as needed

Question 29

Why does [HCOs]/[CO2] ratio not change much?

Answer 29

Human body secretes CO2 as gas in lungs but then is replenished by metabolism of fuels in tissues . CO2 dissolved is in equilibrium w/ CO2 gas . Kidneys can retain or excrete base HCO3 as needed

Question 30

Does carbonate buffer system have more conjugate base or acid and what does this mean?

Answer 30

Base, it can buffer additions of acid better than additions of base

Question 31

Conversion factor of CO2 anew hy is it needed

Answer 31

[CO2] in mmol/L = 0.03 [CO2 mmHg] | Needed to do Henderson-Hasselbalch so CP2 is in same units as bicarbonate

Question 32

T/F CO2 is not soluble in aqueous environments?

Answer 32

T

Question 33

How is CO2 transported from tissues to lungs?

Answer 33

. Generated in tissues during catabolism of fuels to generate ATP . Converted to very soluble bicarbonate (HCO3) that is carried to lungs

Question 34

What occurs w/ CO2 in tissues

Answer 34

. CO2 diffuses into erythrocyte . Carbonic anhydrase catalyzes hydration of CO2 and H2O which dissociates to release H+ and HCO3- . Cl-HCO3 exchanges (band 3 antiport transporter) exports HCO3 while importing CL to maintain electrical neutrality

Question 35

CO2 in the lung

Answer 35

.dissolved CO2 exhaled . Law of mass action moves carbonic anhydrase in opposite direction . Brings HCO3 into erythrocyte to form CO2 which can cross membrane to be exhaled

Question 36

Respiratory acidosis

Answer 36

. Lungs aren’t excreting enough acid as CO2 . Acid accumulates in blood and pH drops . Ex: blocked airway, emphysema, COPD

Question 37

Respiratory alkalosis

Answer 37

. Lungs excrete too much acid as CO2 causing inc. in blood pH . Ex: hyperventilation

Question 38

Metabolic acidosis

Answer 38

. Body generates too much acid that can’t be excreted by lungs . ex:lactic acid, diabetic ketoacidosis, oral ingestion of acid

Question 39

Metabolic alkalosis

Answer 39

. Someone has alkaline blood and it not result of respiratory imbalance . Ex: excess vomiting of stomach contents, ingestion of antacids

Question 40

Compensation for pH

Answer 40

. Involves changes in lung and kidney | . Metabolic imbalance compensated w/ respiratory and vice versa

Question 41

Body pH regulators and how quickly they can mediate

Answer 41

. Buffers: accommodate acid/ base additions almost immediately . Lungs: respiratory rate via loss/retention of CO2 in minutes . Kidneys: regulates loss of H, ammonia, bicarbonate, and others in matter of minutes to hours

Question 42

Serum EBAL

Answer 42

. Anion gap . EBAL = [Na] - ([Cl] + [HCO3]) . Represents differences btw total primary cations and anions measured in blood . Sometimes K included

Question 43

high anion gap is typical of ____

Answer 43

Metabolic acidosis

Question 44

Stomach pH

Answer 44

1-3

Question 45

Small intestine pH

Answer 45

6-8

Question 46

Where are drugs absorbed best across membranes?

Answer 46

. At pH where dissociation of side chain results in neutral molecule since drugs go through protein transporters or hydrophobic nature of neutral molecule allows it to pass through membrane

Question 47

Acidic amino acid (aspartic acid) side chain pK value

Answer 47

3.9

Question 48

Basic amino acids (arginine) pK value

Answer 48

6.0

Question 49

Insulin characteristics

Answer 49

. Small protein, net charge -1.8 . Naturally water soluble . Degraded rapidly in body

Question 50

Insulin glargine characteristics

Answer 50

. Less water soluble due to charge closer to 0 (+0.2) . Injected subcutaneously and precipitates at pH of body . Dissolves slowly over time causing better long term glycemic control and fewer injections

Question 51

How to distinguish btw respiratory and metabolic acidosis

Answer 51

. If respiratory, CO2 and [HCO3] will also be high | . If metabolic then [HCO3] will be low and [CO2] will be low

Question 52

How to distinguish btw respiratory and metabolic alkalosis

Answer 52

. Respiratory then [CO2] and [HCO3] will be low | . Metabolic only through consumption of base of vomiting a ton

Question 53

What if pH is normal but [CO2] and [HCO3] are not w/in normal range?

Answer 53

. Underlying pH disorder that is being compensated . High edge of normal pH is alkalosis . Low edge of normal pH is acidosis