Week 7 Lec: RBC Structure, Metabolism, Destruction, Functions Flashcards

1
Q

Term describing the dynamics of RBC production and destruction.

A

Erythrokinetics

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2
Q

Name given to the collection of all stages of erythrocytes throughout the body, developing precursor in the bm and the circulating RBC in peripheral blood.

A

Erythron

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3
Q

A hormone produced in the kidney in response to tissue hypoxia.

A

Erythropoietin (EPO)

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4
Q

A growth hormone for the production and proliferation of RBC.

A

Erythropoietin (EPO)

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5
Q

Where is EPO produced?

A

peritubular fibroblast in the kidney

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6
Q

Specific Action of EPO?

A
  1. Induces committed progenitor cells in the bone marrow to differentiate and proliferation into pronormoblast.
  2. Shortens the generation time of pronormoblast.
  3. Promotes the early release of reticulocytes to the peripheral blood.
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7
Q

Elevated EPO levels are observed in?

A
  1. Erythroid hyperplasia
  2. Polycythemia
  3. Hemorrhages
  4. Increased RBC destruction
  5. Testosterone
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8
Q

Decreased EPO level is seen in?

A

anemia

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9
Q

Mature RBCs should be?

A

soft and pliable

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10
Q

Mature RBC shape?

A

Biconcave disk (doughnut-shaped with a depressed area rather than a hole in the center)

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11
Q

Mature RBC size?

A

7 – 8 um in diameter

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12
Q

With _____ stain, central pallor (1/3) is seen.

A

Wright’s

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13
Q

Carries the oxygen to the cells of the body which is transported in a chemical combination with hemoglobin, a combination of heme (iron) and globin.

A

Mature RBC

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14
Q

The deficiency in the presence or metabolism of RBC results to decrease in?

A

hemoglobin and oxygen-carrying capacity

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15
Q

Mature RBC includes the assessment of?

A

– Color or Hemoglobin Content (Anisochromia)
– Size (Anisocytosis)
– Shape (Poikilocytosis)
– Structures and Inclusions
– Artifacts and Abnormal Distribution Patterns

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16
Q

Protein percentage?

A

52%

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17
Q

2 Types of Protein?

A
  1. Integral Protein
  2. Peripheral Protein
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18
Q

Integral Protein consists of?

A

Glycophorin A and Component A

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19
Q

Peripheral Protein consists of?

A

Spectrin and Actin

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20
Q

Lipid percentage?

A

40%

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21
Q

Internal Surface lipids?

A
  • Phosphatidylethanolamine
  • Phosphatidylinositol
  • Phosphatidylserine
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22
Q

A ligand (binding) for phagocytosis of dead RBC.

A

Phosphatidylethanolamine

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23
Q

Important in complement regulatory proteins; deficiency can lead to hematologic problems such as PNH.

A

Phosphatidylinositol

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24
Q

Signals the death of RBC; important for clearance.

A

Phosphatidylserine

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25
Q

External Surface lipids?

A
  • Phosphatidylcholine
  • Glycolipid
  • Sphingomyelin
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26
Q

Most abundant lipid that maintains the fluidity and structure of RBC membrane.

A

Phosphatidylcholine

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27
Q

It maintains the cholesterol content of RBC.

A

Lecithin cholesterol acyltransferase (LCAT)

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28
Q

Problems in Lecithin cholesterol acyltransferase (LCAT) cause?

A

acanthocytes

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29
Q

Carbohydrates percentage?

A

8%

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30
Q

Carbohydrates are supported in the RBC membrane by?

A

transmembrane protien

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31
Q

For determining the blood type.

A

Carbohydrates in RBC membrane

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32
Q

A antigen contains?

A

N-Acetyl-D-Galactosamine

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33
Q

B antigen contains?

A

D-Galactose

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34
Q

AB blood type contains?

A

N-Acetyl-D-Galactosamine and D-Galactose

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35
Q

O blood type contains?

A

none

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36
Q

Function of vertical interactions in the RBC membrane?

A

stabilizes the lipid bilayer membrane

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37
Q

Function of horizontal interactions in the RBC membrane?

A

support the structural integrity of RBC membrane

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38
Q

Vertical Anchorage?

A
  1. TRANSMEMBRANE Proteins
  2. INTEGRAL Proteins
  3. Traverses across the bilipid layer
  4. Band 3
  5. Glycophorins (A, B, C)
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39
Q

Horizontal/Lateral Anchorage?

A
  1. CYTOSKELETON proteins
  2. PERIPHERAL proteins
  3. Because the skeletal proteins do not penetrate the bilayer, they are also called peripheral proteins (spreads)
  4. α-spectrin and β-Spectrin
  5. Actin
  6. Protein 4.1
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40
Q

Membrane Proteins: Integral Proteins?

A
  1. Band 3
  2. Aquaporin
  3. Glycophorin A, B, and C
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41
Q

Anion transporter.

A

Band 3

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42
Q

Band 3 comprises how many percent of the total protein?

A

27%

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43
Q

Important for the prevention of surface loss.

A

Band 3

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44
Q

Water transporter.

A

Aquaporin

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45
Q

With Colton Antigen.

A

Aquaporin

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46
Q

Component of aquaporin that is also present in tubules of the kidney and can determine blood type.

A

Colton Antigen

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47
Q

Sialic acid transporter location of MN blood group antigen.

A

Glycophorin A

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48
Q

Glycophorin A percentage?

A

85% GP

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49
Q

Ss blood group antigen.

A

Glycophorin B

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50
Q

Glycophorin B percentage?

A

45% GP

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51
Q

Gerbich blood system.

A

Glycophorin C

52
Q

Glycophorin C percentage?

A

10% GP

53
Q

Membrane Proteins: Peripheral Proteins?

A
  1. Spectrin
  2. Actin
  3. Protein 4.2
  4. Adducin
  5. Ankyrin
  6. Tropomyosin
  7. Tropomodulin
54
Q

Flexible, rod–like molecules responsible for biconcave shape of RBC.

A

Spectrin

55
Q

Binding sites for actin filaments and protein 4.1 - forming a junctional complex.

A

Spectrin

56
Q

Responsible for the contraction and relaxation of the membrane.

A

Actin

57
Q

Stabilizes actin–spectrin interactions.

A

Protein 4.2

58
Q

Stabilizes interaction of spectrin with actin.

A

Adducin

59
Q

Adducin is influenced by?

A

calmodulin–actin interaction

60
Q

A multifunctional molecule that regulates activities of a large number of proteins in the cell.

A

Calmodulin

61
Q

Interacts with band 3 and spectrin to achieve linkage.

A

Ankyrin

62
Q

It regulates actin polymerization.

A

Tropomyosin

63
Q

It controls the actin filaments length.

A

Tropomodulin

64
Q

__________ is an important property of red cell function.

A

Deformability

65
Q

Red Cell Mechanics is influenced by?

A
  • Cell shape (ratio of cell surface area to cell volume)
  • Cytoplasmic viscosity (regulated by MCHC and thus cell volume)
  • Membrane deformability and stability
66
Q

Biconcave disc shape creates an advantageous _________________.

A

surface area/volume relationship

67
Q

Cell shape facilitates?

A

deformation whilst maintaining constant surface area

68
Q

____________________ results in biconcave shape and improved deformability.

A

Progressive loss of intracellular and membrane components

69
Q

_________ will result in more spherical shape with less redundant surface area, and thus less capacity for deformability and diminished survival.

A

SA/V ratio alterations

70
Q

True or false: Membrane loss = reduced SA.

A

True

71
Q

True or false: Increase in cell water content = increased volume.

A

True

72
Q

True or false: During pressure upon RBC, spectrin molecules undergo irreversible change in conformation: some uncoiled and extended, others compressed and folded.

A

False. Should be reversible.

73
Q

During extreme or sustained pressure, membrane exhibits?

A

permanent “plastic” deformation

74
Q

Deformability can be reduced by?

A

increases in associations between skeletal proteins or between skeletal and integral (esp band 3) proteins

75
Q

Cytoplasmic contents of RBCs include?

A
  • potassium ions
  • sodium ions
  • glucose
  • intermediate products of glycolysis
  • enzymes
76
Q

Importance of Energy Metabolism?

A
  • transport of oxygen/RBCs
  • maintain activities/physical characteristics of RBCs
  • survival of RBCs within 120 days
77
Q

Embden-Meyerhof pathway utilizes _____ of RBC total glucose.

A

90%

78
Q

Efficient cellular metabolism depends on?

A

long-lived enzymes

79
Q

Major source of essential cellular energy.

A

Embden-Meyerhof pathway

80
Q

Glucose undergoes glycolysis (glucose to lactate) to form ATPs.

A

Embden-Meyerhof pathway

81
Q

Maintains pyridine nucleotides in a reduced state to permit their function in oxidation-reduction reactions within the cell.

A

Embden-Meyerhof pathway

82
Q

Deficiencies in the production of ATP can be exhibited by?

A
  • Premature cell death due to inherited defects in glycolysis
  • Loss of viability during the storage of blood for transfusion
83
Q

Number of ATP produced in Embden-Meyerhof pathway?

A

4

84
Q

ATP net gain in Embden-Meyerhof pathway?

A

2

85
Q

True or false: Embden-Meyerhof pathway is anaerobic.

A

True

86
Q

Oxidative catabolism of glucose with reduction of NADP (nicotinamide-adenine dinucleotide phosphate) to NADPH (reduced form of NADP) which is required to reduce glutathione.

A

Oxidative Pathway or Hexose Monophosphate Shunt

87
Q

Oxidative Pathway is increased with?

A

increased oxidation of glutathione

88
Q

If Oxidative Pathway is defective, the amount of reduced glutathione becomes insufficient to neutralize oxidants, which causes?

A

denaturation of globin (Heinz bodies)

89
Q

Oxidative Pathway or Hexose Monophosphate Shunt extends the life of RBCs by?

A

maintaining membrane protein, lipids, enzymes, and hemoglobin iron in reduced ferrous state

90
Q

The only means of generating NADPH for glutathione reduction.

A

G6PD/Glucose-6-phosphate dehydrogenase

91
Q

Who maintains reduced glutathione?

A

NADPH

92
Q

Function of glutathione?

A
  • reduces peroxides
  • protects proteins, lipids, and heme iron form oxidation
93
Q

Depends on Embden-Meyerhof pathway for the reduced pyridine nucleotides that keeps hgb in a reduced ferrous state.

A

Methemoglobin Reductase Pathway

94
Q

Prevent the oxidation of heme iron.

A

Methemoglobin Reductase Pathway

95
Q

Methemoglobin Reductase Pathway requires the reducing action of?

A

NADH and the enzyme methemoglobin reductase

96
Q

Important in the oxygen-carrying capacity of RBCs.

A

Leubering-Rapoport Pathway

97
Q

This mechanism is low in energy consumption.

A

Leubering-Rapoport Pathway

98
Q

Capable of regulating oxygen transport even with hypoxia and acid-base disorders.

A

Leubering-Rapoport Pathway

99
Q

Leubering-Rapoport Pathway permits accumulation of?

A

2,3 DPG / 2,3 Diphosphoglyceric Acid

100
Q

In Leubering-Rapoport Pathway, increase in ________________ results in the binding of 2,3 DPG which stimulates glycolysis.

A

deoxyhemoglobin

101
Q

Maintains cellular energy by generating ATP.

A

Embden Meyerhof

102
Q

Prevents denaturation of globin of the hemoglobin molecule by oxidation.

A

Oxidative or Hexose-monophosphate shunt

103
Q

Prevents oxidation of heme iron.

A

Methemoglobin reductase

104
Q

Regulates oxygen affinity of hemoglobin

A

Leubering-Rapoport

105
Q

loss of a portion of the erythrocytes membrane, accompanied by loss of cellular contents, including hemoglobin

A

Fragmentation

106
Q

passing of water into the red cell as to ultimately burst it

A

Osmotic lysis

107
Q

ingestion of whole red cells by circulating monocytes or neutrophil or by fixed macrophages of the mononuclear phagocyte system

A

Erythrophagocytosis

108
Q

complement has the ability to attach itself to the cells and induce lysis

A

Complement induced cytolysis

109
Q

when hb is exposed to oxidant stress and the mechanism to protect the cell from such damage fails to work, denatured hb precipitates forming inclusion bodies are known as Heinz bodies

A

Hemoglobin denaturation

110
Q

2 Types of Destruction?

A
  1. Intravascular hemolysis
  2. Extravascular hemolysis
111
Q

lysis of erythrocytes which occur within the circulation through the classic pathway

A

Intravascular hemolysis

112
Q

It is the usual outcome of sensitization of erythrocytes with complement.

A

Intravascular hemolysis

113
Q

10% of aged red cell undergo this destruction.

A

Intravascular hemolysis

114
Q

Type of catabolism: Happens inside the blood vessels

A

Intravascular Catabolism

115
Q

Type of catabolism: Mechanical Hemolysis & Fragmentation Hemolysis

A

Intravascular Catabolism

116
Q

Type of catabolism: Happens in HEMOGLOBINOPATHIES, blood transfusion incompatibilities (destroyed before going to the spleen)

A

Intravascular Catabolism & Extravascular Catabolism

117
Q

Type of catabolism: Macrophage-Mediated Hemolysis (macrophage destroys the RBC)

A

Extravascular Catabolism

118
Q

Type of catabolism: Happens in senescent RBCs

A

Extravascular Catabolism

119
Q

A transport protein of hemoglobin that brings hemoglobin to the liver and some to kidney.

A

Haptoglobin

120
Q

A crystal that indicates intravascular hemolysis.

A

Hemosiderin

121
Q

Heme absorbed into albumin forming methemalbumin and converted to Hemopexin; Heme directly converted to Hemopexin

A

Haptoglobin – Hemopexin – Methealbumin Salvage System

122
Q

True or false: There should be no Heme in plasma/should be cleared in the blood stream.

A

True

123
Q

Laboratory Diagnosis of Intravascular hemolysis?

A
  1. Decreased haptoglobin (excessive RBC destruction utilizes haptoglobin)
  2. Increased Hemopexin (excessive free hemoglobin converted)
  3. Increased hemoglobinuria and hemosiderinuria (over-saturated free hemoglobin)
124
Q

Causes of Intravascular Hemolysis: Activation of complement on RBC Membrane?

A
  • ABO mismatched blood transfusion
  • Paroxysmal cold hemoglobinuria
  • Paroxysmal nocturnal hemoglobinuria
125
Q

Causes of Intravascular Hemolysis: Toxic Microenvironment of the RBC?

A
  • Burns
  • Snake bites
  • Bacterial - Clostridium perfringens sepsis
  • Parasitic infections - Plasmodium malariae
126
Q

Causes of Intravascular Hemolysis: Physical or Mechanical Trauma to the RBC?

A
  • Acute drug rxn in G6PD deficiency
  • Mechanical heart valves
127
Q

Causes of Extravascular Hemolysis?

A
  • Bacterial/Viral infections
  • Drug-induced
  • Autoimmune
  • Microangiopathy-Malignancy DIC (Disseminated intravascular coagulation), TTP (Thrombotic thrombocytopenic purpura), Eclampsia
  • Hemoglobinopathies
  • Membrane defects-spherocytosis, elliptocytosis, acanthocytosis
  • Metabolic defects-G6PD deficiency/oxidant drugs