pH, acidosis/alkalosis, membranes Flashcards Preview

NBDE PART 1 BIOCHEM/PHYSIOLOGY > pH, acidosis/alkalosis, membranes > Flashcards

Flashcards in pH, acidosis/alkalosis, membranes Deck (112):
1

the isoelectric point (pI) is
a. the pH at which the number of positive and negative charges on a molecule equal each other
b. the pH at which the number of positive and negative charges in a solution equal each other

the pH at which the number of positive and negative charges on a molecule equal each other = the pH at which a solute has NO NET ELECTRICAL CHARGE and does not move in an electric field

2

why is isoelectric point pI important?

soln containing a mixture of amino acids can be separated based on direction and relative rate of their migration when placed in an electric field at a known pH. same applies to proteins

3

the pK is the property of __ group

individually ionized group (unlike pI = property of whole molecule)

4

at a pH above an amino acids' pI it will move

toward the positive electrode (the anode) when placed in electric field

5

at physiologic pH ALL amino acids have

both a + charged amino group and a - charged COO group.

6

at physiological pH all amino acids are called

zwitterions = dipolar ions

7

given OH- concentration of 10^-4 M what is the pH

Kw = H+ x OH-
Kw = 10^-14
(10^-14)/(10^-4) = H+
10^-10 = H+ ==> take -log of each side
pH = 10

8

most important physiological buffer system in body is

carbonic acid and bicarbonate

9

proteins are pH buffers mainly through their __ side chains

histidine

10

the pH of plasma in arterial blood is

7.4

11

the pH of plasma in venous blood is

6.35 (lower because CO2 in the form of carbonic acid is returning to lungs for exchange)

12

Carbonic acid is formed _ from CO2 and water

spontaneously

13

enzyme that accelerates formation of carbonic acid

carbonic anhydrase in erythrocytes

14

the phosphate buffer is important only in the __ compartment

intracellular compartment in which phosphate is the major inorganic anion

15

albumin has 16 histidine residues with pK values not far from the blood pH of 7.4. like phosphate, proteins are more important buffer systems where

in the cell (vs in the plasma)

16

buffer systems are made up of

weak acid = proton donor
and a salt = conjugate base of an acid = proton acceptor

17

hemoglobin is a major intracellular/extracellular buffer

intracellular

18

can the Henderson hasselbalch equation predict dissociation constants

no

19

Henderson hasselbalch equation used to

predict the pH that acid buffers work best at

20

the larger the Ka the _ the acid

stronger

21

pH = pKa when

acid is half neutralized

22

the pH of a buffer system depends on the

pk of the weak acid and the ratio of molar concentrations of the weak acid and salt

23

the optimum pH for an enzyme is the pH that facilitates the

most rapid reaction rate

24

a buffer is most effective when pH = pKa but it still works well within _pH unit of its pKa

1

25

body uses all these to control acid base except:
a. excess acid excreted in urine
b. pH buffers in blood
c. excretion of CO2
d. filtering blood by the spleen

filtering blood by the spleen

26

body has 3 lines of defense against acidosis and alkalosis

buffer systems
alveolar ventilation
kidney excretion

27

the respiratory center in the __ responds directly to _ and _

medulla oblongata
CO2 and pH

28

kidneys excrete

H+ in acidosis and HCO3- in alkalosis = long term mechanism that acts in hours or days

29

the pka of the bicarb-CO2 buffer system is

6.1

30

to calculate pH of blood =

6.1 + log (bicarb/0.03xCO2 partial pressure)

31

an arterial blood pH < 7.35 is called:
acidosis
acidemia

acidemia

acidosis is the pathological state that occurs from acidemia

32

arterial blood pH > ? is called alkemia

7.45

33

pathological state of alkemia is called

alkalosis

34

if you administer a high nitrous oxygen mixture (90:10) to a patient this will cause

respiratory depression = respiratory acidosis

35

most important lab test for distinction bw metabolic/respiratory acidosis is the determination of the total

plasma CO2.

36

in respiratory acidosis, the __ is the cause

high CO2 retention

37

in metabolic acidosis caused by

patient hyperventilating in an attempt to eliminate excess carbonic acid

38

the cell plasma membrane is a fluid mosaic of:
a. lipids and carbs
b. proteins and carbs
c. lipids and proteins
d. carbohydrates

lipids and proteins

39

carbohydrates are attached to proteins and lipids on the ___ of the cell membrane

exterior side of the cell membrane

40

our bodies make mostly strong/weak acids

weak acids ie. carbonic acids
except HCl

41

why is membrane called fluid mosaic

bc lipid and proteins can diffuse laterally within the plane of the membrane

42

pH and H+ relationship is an __ relationship

inverse

43

integral proteins are associated with the hydrophobic/hydrophilic phase of the bilayer

hydrophobic

44

the pH of the ECF can be measured using

pH = pKa + log [HCO3-]/[CO2]

45

is it the ratio or the absolute values for bicarbonate and dissolved CO2 that determines pH

ratio!

pH = pKa + log [HCO3-]/[CO2]

46

when the ration of [HCO3-]/[CO2] is ___ pH is equal to 7.4

20:1

47

the body's normal ECF pH range is

7.35-7.45

48

our body is constantly making acids/bases?

acids = acids are waste products from our metabolism

49

about half of the molecules in an average membrane are

phospholipids

50

3 lines of defense for buffering? 1st line is?

chemical buffers = our first line of defense bc it is the fastest. reacts if it goes above 7.45 or below 7.35

51

if you are making a lot of acid = acidosis = reaction is favored which way?
CO2 + H2- H2CO3 H+ + HCO3-

reaction is favored to the left so the H+ will be soaked up
you want your buffer to act like a base and soak up the hydrogens.

52

if you have alkalosis, shortage of H+ which way does the reaction shift
CO2 + H2- H2CO3 H+ + HCO3-

you want your buffer system to act as an acid and release more H+
will shift to the right = make more acid.

53

HPO4^2- + H+ H2PO4-
is the monophosphate or the diphosphate the acid?

diphosphate is the acid. the mono is the base

54

proteins are made up of amino acids. they have 2 groups that can act like an acid and base

amine group can act as bases: NH2 ==> NH3+
and carboxyl groups can acts as acids and release their H: COOH ==> H+

55

if we were acidodic we would want our proteins to act as bases

amine groups to work

56

buffers are great because they ___
but not as good because

good bc they can act fast
but not good bc can become saturated

57

membrane proteins are __ proteins

globular

58

our second line of defense for acid base balance after chemical buffers is

respiratory system

59

CO2 + H2- H2CO3 H+ + HCO3-
if we raise our CO2 level, which way will we shift

CO2 + H20 H2CO3 H+ + HCO3-
to the right = make more H+ = pH drops

60

Proteins account for about __ the total mass of most membranes

50%

61

a decrease our rate/depth of breathing we will ___ CO2 and make our body ___ pH

retain CO2 = hypoventilation = decreases the pH of the body

62

a decrease in CO2 will __ the pH

raise our pH
CO2 + H20 H2CO3 H+ + HCO3-
if CO2 is low, we soak up the H+
raise the pH

63

if we increase our rate and depth of breathing = CO2 will _ =

hyperventilation = increases pH of blood

64

the non polar side chains of integral membrane proteins interact with

membrane lipids

65

integral membrane proteins can be solubilized only with treatments that

destroy the lipid bilayer (action of detergents)

66

say you are in acidosis and your buffers only bring your pH to 7.28 how would you want your respiration to react

want to hyperventilate to get rid of CO2
CO2 + H20 H2CO3 H+ + HCO3-
if we hyperventilate our CO2 level comes down the equation shifts left and hydrogens get soaked up

67

peripheral membrane proteins interact with integral membrane proteins or the __ group of the membrane phospholipids

hydrophilic

68

say you are in acidosis and your buffers only bring your pH to 7.28, lungs hyperventilate and bring us to 7.31. Lungs are 2nd line of defense and also work pretty fast. But they too have limitations. so the third line of defense is

kidneys

69

biological membranes are __ structures only a few molecules thick

sheetlike

70

biological membranes consist mainly of

lipids and proteins (carbs are attached to exterior)

71

T/F the kidneys can make bicarb from scratch

true

72

the membrane lipids are small molecules with hydrophobic and hydrophilic groups that from lipid bilayers in aqeous media. the __ center of the bilayer forms a barrier to the flow of polar molecules

hydrophobic

73

proteins and lipids in membranes are held together by
covalent/non covalent interactions

non covalent

74

ABG test = arterial blood gas test measures

amount of gas in blood (oxygen and CO2)
bicarb
and pH

75

the lipid distribution in the membrane is symmetrical or asymmetrical. why?

asymmetrical = bc most phospholipids in the CYTOPLASMIC inner and most of the glycolipids are in the exoplasmic leaflet

76

in respiratory acidosis we have

they have a pH that is low and a CO2 level that is high. the high CO2 is causing the low pH

77

what can cause high CO2?

emphysema (trap CO2 in lungs and blood)
pulmonary edema
chronic bronchitis = airways are inflamed and narrow.
opiod overdose
neuromuscular disease (myasthenia gravis, Guillian-Barre syndrome)
injury to brainstem

78

where are phosphatidylinositol, phosphatidylserine, phosphatidylethanolamine found

INSIDE on cytoplasm

79

where are phosphatidylcholine and sphingomyelin found

OUTSDE (exoplasmic) leaflet
= glycolipids

80

what are globular proteins

integral and peripheral proteins

81

globular proteins are held by __ interactions bw lipid and hydrophobic domains in the proteins

hydrophobic

82

the lipid bilayer is __ to small inorganic ions such as sodium and protons

impermeable

83

all non covalent structures are

fragile

84

can coenzymes and metabolic intermediates cross the membranes

no they are water soluble

85

electrical conductivity of lipid bilayer is low/high

low bc ions cant pass

86

in respiratory alkalosis, the pH is increased due to

decreased CO2
CO2 + H20 H2CO3 H+ + HCO3-

87

why would your CO2 be low?

hyperventilating

88

if you go up in altitude you will hyperventilate/hypo?

hyperventilate bc there is less oxygen so you will try to breath faster to get more oxygen which makes you breathe off more co2

89

in anxiety/fear/pain you will hyperventilate/hypo?

hyperventilate

90

aspirin overdose would cause hyperventilate/hypo

hyperventilate = aspirin stimulates the breathing centers! unlike opium.

91

why doesn't aspirin (salicylic acid) cause acidosis?

because its effect on the respiratory system is greater

92

fever would cause you to hyperventilate/hypo

hyperventilate

93

only _ and _ can pass easily thru lipid bilayer

water and gases

94

in membranes passive diffusion is limited to _ molecules

lipid soluble

95

water soluble molecules require _ to cross membrane

carrier mediated transport

96

uniport is __

facilitated diffusion

97

respiratory alkalosis/acidosis prob is

respiratory

98

in metabolic acidosis ABG would be

low pH, because you are low on base,

99

why would you be lacking base?

sever diarrhea, aspirin overdose (early poisioning), lactic acidosis, ethylene glycol poisoning
Ketoacidosis: diabetes, alcoholism, fasting/starvation

100

why does diarrhea cause acidosis?

bc no time for bicarb to reabsorb bc losing it too fast

101

main reason for metabolic alkalosis

severe emesis (vomiting)

102

in metabolic alkalosis you have increased

pH and HCO3-

103

in metabolic acidosis you have decreased

pH and HCO3-

104

given:
pH = 7.31
Pa CO2 = 70mmHg
Pa O2 = 54mmHg
HCO3- = 34mEq/L
what type of acid base disturbance is this?

normal pH should be 7.35-7.45: so he is acidemia.
Pa (arterial) should be 40mmHg
Pa O2 should be 100mmHg
HCO3- = 22-26mEq/L
so we know it is acidosis by pH ==> now is it respiratory or metabolic?
CO2 + H20 ==>H2CO3==> H+ + HCO3-
the bicarb here is high. would a high bicarb cause the pH to go down? no. so it is not metabolic acidosis.
CO2 is high, that would cause the pH to drop so it is respiratory acidosis! the bicarb is high because the kidneys are trying to compensate

105

pH = 7.26
Pa CO2 = 26mmHg
HCO3- = 14 mEq/L
what type of disturbance?

CO2 + H20 H2CO3 H+ + HCO3-
pH is low = acidosis
low CO2 would not cause acidosis, so it is not respiratory
low bicarb would so it is the cause = metabolic acidosis

106

Blood pressure 90/40
pulse rate 130/min
respiration 32/min deep and rapid
pH - 7.22
PaCO2 = 20mmHg
PaO2 = 112mmHg
HCO3- = 8mEq/L

pH is low = acidosis
CO2 + H20 = H2CO3 = H+ + HCO3-
CO2 is low so that cant be the cause (rxn would shift left and soak up H+)
HCO3- is low so shift to the right = metabolic acidosis

107

pH = 7.1
PaCO2 = 78mmHg
PaO2 = 50mmHg
HCO3- = 27mEq/L

pH is low - acidosis
CO2 + H20 = H2CO3 = H+ + HCO3-
CO2 is high = pushed rxn to right = acidosis

108

carbaminohemoglobin

carbaminohemoglobin = a compound of haemoglobin and carbon dioxide = 10% of carbon dioxide is carried in blood this way (85% carried in blood as bicarbonate [hydrogen carbonate], 5% carried as free CO2, in solution

109

Denaturation usually destroys all the following except:
hydrogen bonds
covalent bonds
electrostatic bonds
hydrophobic bonds

covalent

110

the Michaelis menten constant is

Km

111

how does NaF inhibit glycolysis in bacteria?

Fluoride is a known competitor of enolase’s substrate 2-PG. The fluoride is part of a complex with magnesium and phosphate, which binds in the active site instead of 2-PG.[4] As such, drinking fluoridated water provides fluoride at a level that inhibits oral bacteria enolase activity without harming humans

112

what enzyme converts trypsinogen to trypsin

enterokinase