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Hematology 1 [LEC] > MODULE 3 UNIT 2 > Flashcards

MODULE 3 UNIT 2 Flashcards

1
Q

main function of hemoglobin

A

to transport oxygen

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2
Q

oxygen has to depend on hemoglobin found in red blood cells for its transport to the different organs and tissues of the human body

A

non-water soluble

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3
Q

Hemoglobin increases (?) in blood by about a hundredfold.

A

O2 solubility

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4
Q

This means that without hemoglobin, in order to provide sufficient oxygen to the tissues, blood would have to make a complete circuit through the body in less than a second, instead of the minute that it actually takes.

A

Hemoglobin increases O2 solubility in blood by about a hundredfold.

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5
Q

That would take a mighty powerful heart, which in normal circumstances cannot be maintained by the human heart leading to increased cardiac output that may result to heart failure.

A

Hemoglobin increases O2 solubility in blood by about a hundredfold.

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6
Q

each of the four heme iron atoms in a hemoglobin molecule can reversibly bind one oxygen molecule

A

oxygenation

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7
Q

is bound by each gram of hemoglobin

A

1.34 mL of oxygen

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8
Q

Let’s follow the path of oxygen from the lungs to the peripheral tissues.
o Oxygen diffuses from the (?) of the lungs, little sacs at the end of the finely divided air passageways in the lung into the (?) of the bloodstream and then into the (?), where it binds to hemoglobin.

A

alveoli
capillaries
red blood cells

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9
Q

The concentration of oxygen is relatively high in the alveoli, about (?) which means that Hb is virtually 100% saturated in the lungs and all four heme molecules have an O2 molecule bound to them.

A

100 mmHg

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10
Q

The reference interval for arterial oxygen saturation is

A

96% to 100%

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11
Q

affinity of hemoglobin for oxygen relates to the

A

partial pressure of oxygen (PO2)

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12
Q

often defined in terms of the amount of oxygen needed to saturate 50% of hemoglobin

A

P50 value

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13
Q

plots the percent oxygen saturation of hemoglobin versus the PO2

A

oxygen dissociation curve of hemoglobin

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14
Q

indicates low hemoglobin affinity for oxygen at low oxygen tension and high affinity for oxygen at high oxygen tension

A

sigmoidal

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15
Q

contributes to the shape of the curve

A

Cooperation among hemoglobin subunits

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16
Q

Hemoglobin that is completely deoxygenated has

A

little affinity for oxygen

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17
Q

The secret to hemoglobin’s success as an oxygen delivery molecule is the fact that it has (?) that communicate to each other.

A

four subunits

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18
Q

Evidence for this is provided by hemoglobin’s (?) in oxygen binding.

A

“cooperativity”

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19
Q

In other words, the binding of one O2 molecule affects the binding of others, as we can see by the following:
o In order to achieve 25% saturation (an average of 1 O2 molecule per hemoglobin), the amount of O2 needs to be about (?)
o In order to achieve 50% saturation (an average of 2 O2 molecules per hemoglobin), the amount of O2 needs to be about (?)

A

18 mm Hg
27 mm Hg

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20
Q

Therefore, it is easier to bind the second molecule of O2 than the first. This was illustrated by (?), Nobel Prize winners for Chemistry for their studies of the structures of hemoglobin and myoglobin.

A

Max Perutz and John Kendrew

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21
Q

hemoglobin was found to have two different forms or shapes

A

X-ray diffraction

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22
Q

dependent on the presence or absence of oxygen

A

conformation or shape

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23
Q

has a relatively low attraction for oxygen

A

deoxyhemoglobin

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24
Q

has a relatively low attraction for oxygen, but when one molecule of oxygen binds to a heme group, the structure changes to the oxygenated form, which has a greater attraction for oxygen.

A

deoxyhemoglobin

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25
Q

when one molecule of oxygen binds to a heme group, the structure changes to the (?) form, which has a greater attraction for oxygen.

A

oxygenated

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26
Q

the second molecule of O2 binds more easily, and the third, and fourth even more easily

A

TRUE

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27
Q

oxygen affinity of (?) is many times greater than that of deoxy-hemoglobin

A

oxy-hemoglobin

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28
Q

illustrates the relationship between oxygen saturation of hemoglobin and the partial pressure of oxygen

A

oxygen dissociation curve

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29
Q

P50 is the partial pressure of oxygen (O2) needed for 50% O2 saturation of hemoglobin.

A

Normal (N)

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30
Q

↓ P50

A

Left-shifted (L)

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31
Q

↑ P50

A

Right-shifted (R)

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32
Q

o Hemoglobin F and hemoglobin variants

A

Left-shifted (L)

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33
Q

o Pulmonary insufficiency
o Congestive heart failure
o Severe anemia
o Hemoglobin variants

A

Right-shifted (R)

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34
Q

 ↓ 2,3-bisphosphoglycerate (2,3-BPG)

A

Left-shifted (L)

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35
Q

 ↓ H+ ions (↑pH)

A

Left-shifted

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36
Q

 ↓ (PCO2)

A

Left-shifted (L)

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37
Q

 ↓ body temperature

A

Left-shifted (L)

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38
Q

 ↑ oxygen affinity

A
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39
Q

 Alkalosis

A

Left-shifted (L)

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40
Q

multiple transfusion of stored blood

A

Left-shifted (L)

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41
Q

 ↑ 2,3-BPG

A

Right-shifted (R)

42
Q

(e.g., in response to hypoxic conditions such as in high altitudes)

A

Right-shifted (R)

43
Q

 ↑ H+ ions (↓ pH)

A

Right-shifted (R)

44
Q

 ↑ PCO2, and/or temperature

A

Right-shifted (R)

45
Q

 ↓ oxygen affinity

A

Right-shifted (R)

46
Q

A patient with arterial and venous PO2 levels in the reference intervals (80 to 100 mm Hg arterial and 30 to 50 mm Hg venous)
 ↑ percent oxygen saturation
 ↑ affinity for oxygen

A

Partial pressure of oxygen

47
Q

Strenuous physical activities:
 ↑ cellular respiration
 ↑ metabolic activity
 ↑ CO2
 ↓ O2

A

pH of blood

48
Q

Bohr effect

A

 ↓ affinity for oxygen  ↑ pCO2  ↓ pH  ↑ H+

49
Q

To transport CO2 through the venous blood, it diffuses into the red blood cells combining with water to form carbonic acid (H2CO3).

A

Bohr effect

50
Q

This reaction is facilitated by the enzyme, carbonic anhydrase. The carbonic acid will then dissociate to release H+ and bicarbonate (HCO3 -).

A

Bohr effect

51
Q

a small molecule made in red blood cells

A

2,3-Biphosphoglycerate (2,3-BPG)

52
Q

affects oxygen-binding affinity by binding in a small central cavity of deoxygenated hemoglobin. This shifts the equilibrium towards deoxy-hemoglobin

A

2,3-Biphosphoglycerate (2,3-BPG)

53
Q

The presence of acids leads to:

A

 ↑ H+  ↓ pH  ↑ O2

54
Q

This promotes formation of the deoxy form of hemoglobin, shifting the oxygen dissociation curve to the right, promoting oxygen release to actively respiring tissues.

A

2,3-Biphosphoglycerate (2,3-BPG)

55
Q

At high altitude, when oxygen in the atmosphere is scarce because the air is “thinner,”:

A

 ↑ 2,3- BPG (helping hemoglobin to release more of its bound oxygen = ↑ aerobic capacity)  ↑ CO2  ↓ O2

56
Q

It takes about 24 hours for (?) levels to rise, and over longer periods of time, the levels continue to increase as part of the acclimation effect.

A

2,3-BPG

57
Q

Interestingly, 2,3-BPG does not bind to fetal hemoglobin. This results in tighter binding of oxygen relative to maternal hemoglobin.

A

Giving the developing fetus better access to oxygen from the mother’s bloodstream

58
Q

Through heat transfer, the thermal energy diffuses to the blood in nearby capillaries.

A

 ↑ metabolic rates  ↑ thermal energy  ↑ average kinetic energy  ↑ temperature  ↓ affinity for oxygen

59
Q

is interpreted by the body that cells are working harder thus requiring more oxygen to keep them going

A

• ↑ temperature

60
Q

Hb decrease its affinity for oxygen to facilitate delivery to the tissues

A

• ↑ temperature

61
Q

shifts the oxygen dissociation curve to the right such as when tissues are actively engaged in physical activity, these tissues would require and eventually receive more O2

A

• ↑ temperature

62
Q

Carbon dioxide

A

 ↑ cellular respiration  ↑ metabolic activity  ↑ CO2  ↓ O2  ↑ H+ ions  ↑ 2,3-BPG

63
Q

CO2 diffuses from the tissues to red cells to form H2CO3 which dissociates to H+ and HCO3

A

shift of the curve to the right

64
Q

Once the red cells reach the lungs, O2 will diffuse into the deoxygenated Hb resulting to release of H+ that will combine with HCO3 - to form H2CO3 which in turn will dissociate to water and CO2 where the latter will diffuse out of the cells and eventually expelled by the lungs.

A

Haldane effect

65
Q

describes the binding of oxygen to Hb which promotes the release of CO2

A

Haldane effect

66
Q

are hemoglobins that were previously produced in a normal red blood cell precursor but have been exposed to certain drugs, toxic agents, environmental chemicals or gases

A

Dyshemoglobins

67
Q

are dysfunctional hemoglobins that cannot properly dispense its function of transporting oxygen because the offending agent has modified the structure of the Hb molecule

A

Dyshemoglobins

68
Q

 – produced when Hb is exposed to carbon monoxide which as an affinity of 240 times that of oxygen.

A

Carboxyhemoglobin (COHb)

69
Q

 Binding of (?) shifts the oxygen dissociation curve to the left increasing its affinity and impairing release of oxygen to the tissues.

A

carbon monoxide to Hb

70
Q

 Sources of CO poisoning include

A

house fires, car exhaust, indoor heaters, and stoves

71
Q

occurs during the degradation of heme and contributes to the baseline COHb concentration found in healthy people.

A

Endogenous production

72
Q

In patients afflicted with hemolytic anemias, COHb can reach concentrations of

A

8%

73
Q

Values also may be elevated in severe sepsis.

A

Carboxyhemoglobin (COHb)

74
Q

In smokers, COHb levels may be as high as 15%. As a result, smokers may have a higher (?) to compensate for the hypoxia.

A

hematocrit and polycythemia

75
Q

Treatment involves (?) from the carbon monoxide source and administration of 100% oxygen.

A

removal of the patient

76
Q

The use of (?) is controversial. It is primarily used to prevent neurologic and cognitive impairment after acute carbon monoxide exposure in patients whose COHb level exceeds 25%.

A

hyperbaric oxygen therapy

77
Q

may be detected by spectral absorption instruments at 540 nm

A

Carboxyhemoglobin

78
Q

It gives blood a cherry red color, which is sometimes imparted to the skin of victims.

A

Carboxyhemoglobin

79
Q

A diagnosis of carbon monoxide poisoning is made if the COHb level is greater than (?) in nonsmokers and greater than (?) in smokers.

A

3%
10%

80
Q

 – formed when the iron (Fe+2) in Hb is reversibly oxidized to the ferric (Fe3+) state.

A

Methemoglobin (MetHb or Hemiglobin)

81
Q

 Normally, a small amount of (?) is continuously formed by oxidation of iron during the normal oxygenation and deoxygenation of hemoglobin.

A

Methemoglobin (MetHb or Hemiglobin)

82
Q

 However, methemoglobin reduction systems, predominantly the (?), normally limit its accumulation to only 1% of total hemoglobin.

A

NADH-cytochrome b5 reductase 3 (NADH-methemoglobin reductase) pathway

83
Q

 While it levels up to 25% are generally asymptomatic, increased levels of more that 30% of the total Hb may result to cyanosis, and symptoms of hypoxia (e.g., headache, dyspnea, vertigo, changes in mental status).

A

Methemoglobin (MetHb or Hemiglobin)

84
Q

 Levels greater than 50% have resulted to coma and death.

A

Methemoglobin (MetHb or Hemiglobin)

85
Q

Types of Methemoglobinemia:

A

Acquired Acquired Methemoglobinemia
Hereditary Acquired Methemoglobinemia

86
Q

– also known as toxic methemoglobinemia is due to exposure of affected individuals to exogenous oxidants such as nitrites (e.g., ingestion of nitrite-containing well water, gastroenteritis resulting in nitrite production), primaquine, dapsone or benzocaine

A

Acquired Methemoglobinemia

87
Q

If the level of MetHb is less than 30%, removal of the offending agent may be sufficient for recovery.

A

Acquired Methemoglobinemia

88
Q

If the level is more than 30%, methylene blue, which reduces ferric iron to the ferrous state, is given to patients intravenously.

A

Acquired Methemoglobinemia

89
Q

– due to mutations in the gene that codes for NADHcytochrome b5 reductase 3 (CYB5R3), resulting in a diminished capacity to reduce methemoglobin.

A

Hereditary Methemoglobinemia

90
Q

It may also arise from mutations in the a-, β- , or γ-globin gene, resulting in a structurally abnormal polypeptide chain that favors the oxidized ferric form of iron and prevents its reduction, this phenomenon is called the

A

M hemoglobin or Hb M

91
Q

– a spectral absorption analysis instrument that measures concentrations of oxygenated hemoglobin (oxyHb), deoxygenated hemoglobin (deoxyHb or reduced Hb), carboxyhemoglobin (COHb), and methemoglobin (MetHb) as a percentage of the total hemoglobin concentration in the blood sample.

A

CO-oximeter

92
Q

MetHb shows an absorption peak at

A

630 nm

93
Q

Blood samples with high levels of MetHb have

A

chocolate brown color

94
Q

Since Hb M has different absorption peaks, it may be detected using

A

Hb electrophoresis, high performance liquid chromatography (HPLC) and DNA mutation testing

95
Q

 – is a rare condition that may result from exposure to sulfonamides, acetanilide, phenazopyridine, nitrates, trinitrotoluene, and phenacetin.

A

sulfhemoglobin

96
Q

 is unique because its presence is not detected by co-oximetry.

A

sulfhemoglobin

97
Q

 unlike the other dyshemoglobins, (?) shifts the oxygen dissociation curve to the right, resulting in oxygen being more readily available to tissues.

A

sulfhemoglobin

98
Q

 should be suspected when a patient who has cyanosis has a normal po2 and elevated methemoglobin concentration by co-oximetry but does not respond to methylene blue therapy.

A

sulfhemoglobinemia

99
Q

 treatment involves administering oxygen and discontinuing the offending agent

A

Sulfhemoglobin

100
Q

The main function of hemoglobin (?)

A

is to transport oxygen

Hematology 1 [LEC] (25 decks)

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