pH, acidosis/alkalosis, membranes Flashcards Preview

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

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

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

A

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
Q

why is isoelectric point pI important?

A

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
Q

the pK is the property of __ group

A

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

4
Q

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

A

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

5
Q

at physiologic pH ALL amino acids have

A

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

6
Q

at physiological pH all amino acids are called

A

zwitterions = dipolar ions

7
Q

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

A
Kw = H+ x OH-
Kw = 10^-14
(10^-14)/(10^-4) = H+
10^-10 = H+ ==> take -log of each side
pH = 10
8
Q

most important physiological buffer system in body is

A

carbonic acid and bicarbonate

9
Q

proteins are pH buffers mainly through their __ side chains

A

histidine

10
Q

the pH of plasma in arterial blood is

A

7.4

11
Q

the pH of plasma in venous blood is

A

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

12
Q

Carbonic acid is formed _ from CO2 and water

A

spontaneously

13
Q

enzyme that accelerates formation of carbonic acid

A

carbonic anhydrase in erythrocytes

14
Q

the phosphate buffer is important only in the __ compartment

A

intracellular compartment in which phosphate is the major inorganic anion

15
Q

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

A

in the cell (vs in the plasma)

16
Q

buffer systems are made up of

A

weak acid = proton donor

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

17
Q

hemoglobin is a major intracellular/extracellular buffer

A

intracellular

18
Q

can the Henderson hasselbalch equation predict dissociation constants

A

no

19
Q

Henderson hasselbalch equation used to

A

predict the pH that acid buffers work best at

20
Q

the larger the Ka the _ the acid

A

stronger

21
Q

pH = pKa when

A

acid is half neutralized

22
Q

the pH of a buffer system depends on the

A

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

23
Q

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

A

most rapid reaction rate

24
Q

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

A

1

25
Q

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

A

filtering blood by the spleen

26
Q

body has 3 lines of defense against acidosis and alkalosis

A

buffer systems
alveolar ventilation
kidney excretion

27
Q

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

A

medulla oblongata

CO2 and pH

28
Q

kidneys excrete

A

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

29
Q

the pka of the bicarb-CO2 buffer system is

A

6.1

30
Q

to calculate pH of blood =

A

6.1 + log (bicarb/0.03xCO2 partial pressure)

31
Q

an arterial blood pH < 7.35 is called:
acidosis
acidemia

A

acidemia

acidosis is the pathological state that occurs from acidemia

32
Q

arterial blood pH > ? is called alkemia

A

7.45

33
Q

pathological state of alkemia is called

A

alkalosis

34
Q

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

A

respiratory depression = respiratory acidosis

35
Q

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

A

plasma CO2.

36
Q

in respiratory acidosis, the __ is the cause

A

high CO2 retention

37
Q

in metabolic acidosis caused by

A

patient hyperventilating in an attempt to eliminate excess carbonic acid

38
Q

the cell plasma membrane is a fluid mosaic of:

a. lipids and carbs
b. proteins and carbs
c. lipids and proteins
d. carbohydrates

A

lipids and proteins

39
Q

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

A

exterior side of the cell membrane

40
Q

our bodies make mostly strong/weak acids

A

weak acids ie. carbonic acids

except HCl

41
Q

why is membrane called fluid mosaic

A

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

42
Q

pH and H+ relationship is an __ relationship

A

inverse

43
Q

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

A

hydrophobic

44
Q

the pH of the ECF can be measured using

A

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

45
Q

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

A

ratio!

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

46
Q

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

A

20:1

47
Q

the body’s normal ECF pH range is

A

7.35-7.45

48
Q

our body is constantly making acids/bases?

A

acids = acids are waste products from our metabolism

49
Q

about half of the molecules in an average membrane are

A

phospholipids

50
Q

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

A

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

51
Q

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

A

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
Q

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

A

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

53
Q

HPO4^2- + H+ H2PO4-

is the monophosphate or the diphosphate the acid?

A

diphosphate is the acid. the mono is the base

54
Q

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

A

amine group can act as bases: NH2 ==> NH3+

and carboxyl groups can acts as acids and release their H: COOH ==> H+

55
Q

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

A

amine groups to work

56
Q

buffers are great because they ___

but not as good because

A

good bc they can act fast

but not good bc can become saturated

57
Q

membrane proteins are __ proteins

A

globular

58
Q

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

A

respiratory system

59
Q

CO2 + H2- H2CO3 H+ + HCO3-

if we raise our CO2 level, which way will we shift

A

CO2 + H20 H2CO3 H+ + HCO3-

to the right = make more H+ = pH drops

60
Q

Proteins account for about __ the total mass of most membranes

A

50%

61
Q

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

A

retain CO2 = hypoventilation = decreases the pH of the body

62
Q

a decrease in CO2 will __ the pH

A

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

63
Q

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

A

hyperventilation = increases pH of blood

64
Q

the non polar side chains of integral membrane proteins interact with

A

membrane lipids

65
Q

integral membrane proteins can be solubilized only with treatments that

A

destroy the lipid bilayer (action of detergents)

66
Q

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

A

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
Q

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

A

hydrophilic

68
Q

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

A

kidneys

69
Q

biological membranes are __ structures only a few molecules thick

A

sheetlike

70
Q

biological membranes consist mainly of

A

lipids and proteins (carbs are attached to exterior)

71
Q

T/F the kidneys can make bicarb from scratch

A

true

72
Q

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

A

hydrophobic

73
Q

proteins and lipids in membranes are held together by

covalent/non covalent interactions

A

non covalent

74
Q

ABG test = arterial blood gas test measures

A

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

75
Q

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

A

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

76
Q

in respiratory acidosis we have

A

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

77
Q

what can cause high CO2?

A

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
Q

where are phosphatidylinositol, phosphatidylserine, phosphatidylethanolamine found

A

INSIDE on cytoplasm

79
Q

where are phosphatidylcholine and sphingomyelin found

A

OUTSDE (exoplasmic) leaflet

= glycolipids

80
Q

what are globular proteins

A

integral and peripheral proteins

81
Q

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

A

hydrophobic

82
Q

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

A

impermeable

83
Q

all non covalent structures are

A

fragile

84
Q

can coenzymes and metabolic intermediates cross the membranes

A

no they are water soluble

85
Q

electrical conductivity of lipid bilayer is low/high

A

low bc ions cant pass

86
Q

in respiratory alkalosis, the pH is increased due to

A

decreased CO2

CO2 + H20 H2CO3 H+ + HCO3-

87
Q

why would your CO2 be low?

A

hyperventilating

88
Q

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

A

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
Q

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

A

hyperventilate

90
Q

aspirin overdose would cause hyperventilate/hypo

A

hyperventilate = aspirin stimulates the breathing centers! unlike opium.

91
Q

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

A

because its effect on the respiratory system is greater

92
Q

fever would cause you to hyperventilate/hypo

A

hyperventilate

93
Q

only _ and _ can pass easily thru lipid bilayer

A

water and gases

94
Q

in membranes passive diffusion is limited to _ molecules

A

lipid soluble

95
Q

water soluble molecules require _ to cross membrane

A

carrier mediated transport

96
Q

uniport is __

A

facilitated diffusion

97
Q

respiratory alkalosis/acidosis prob is

A

respiratory

98
Q

in metabolic acidosis ABG would be

A

low pH, because you are low on base,

99
Q

why would you be lacking base?

A

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

100
Q

why does diarrhea cause acidosis?

A

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

101
Q

main reason for metabolic alkalosis

A

severe emesis (vomiting)

102
Q

in metabolic alkalosis you have increased

A

pH and HCO3-

103
Q

in metabolic acidosis you have decreased

A

pH and HCO3-

104
Q
given:
pH = 7.31
Pa CO2 = 70mmHg
Pa O2 = 54mmHg
HCO3- = 34mEq/L
what type of acid base disturbance is this?
A

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
Q

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

A

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

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

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

108
Q

carbaminohemoglobin

A

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

covalent

110
Q

the Michaelis menten constant is

A

Km

111
Q

how does NaF inhibit glycolysis in bacteria?

A

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
Q

what enzyme converts trypsinogen to trypsin

A

enterokinase