Week 7 Lec: RBC Structure, Metabolism, Destruction, Functions Flashcards
(127 cards)
1
Q
Term describing the dynamics of RBC production and destruction.
A
Erythrokinetics
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
3
Q
A hormone produced in the kidney in response to tissue hypoxia.
A
Erythropoietin (EPO)
4
Q
A growth hormone for the production and proliferation of RBC.
A
Erythropoietin (EPO)
5
Q
Where is EPO produced?
A
peritubular fibroblast in the kidney
6
Q
Specific Action of EPO?
A
- Induces committed progenitor cells in the bone marrow to differentiate and proliferation into pronormoblast.
- Shortens the generation time of pronormoblast.
- Promotes the early release of reticulocytes to the peripheral blood.
7
Q
Elevated EPO levels are observed in?
A
- Erythroid hyperplasia
- Polycythemia
- Hemorrhages
- Increased RBC destruction
- Testosterone
8
Q
Decreased EPO level is seen in?
A
anemia
9
Q
Mature RBCs should be?
A
soft and pliable
10
Q
Mature RBC shape?
A
Biconcave disk (doughnut-shaped with a depressed area rather than a hole in the center)
11
Q
Mature RBC size?
A
7 – 8 um in diameter
12
Q
With _____ stain, central pallor (1/3) is seen.
A
Wright’s
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
14
Q
The deficiency in the presence or metabolism of RBC results to decrease in?
A
hemoglobin and oxygen-carrying capacity
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
16
Q
Protein percentage?
A
52%
17
Q
2 Types of Protein?
A
- Integral Protein
- Peripheral Protein
18
Q
Integral Protein consists of?
A
Glycophorin A and Component A
19
Q
Peripheral Protein consists of?
A
Spectrin and Actin
20
Q
Lipid percentage?
A
40%
21
Q
Internal Surface lipids?
A
- Phosphatidylethanolamine
- Phosphatidylinositol
- Phosphatidylserine
22
Q
A ligand (binding) for phagocytosis of dead RBC.
A
Phosphatidylethanolamine
23
Q
Important in complement regulatory proteins; deficiency can lead to hematologic problems such as PNH.
A
Phosphatidylinositol
24
Q
Signals the death of RBC; important for clearance.
A
Phosphatidylserine
25
External Surface lipids?
* Phosphatidylcholine
* Glycolipid
* Sphingomyelin
26
Most abundant lipid that maintains the fluidity and structure of RBC membrane.
Phosphatidylcholine
27
It maintains the cholesterol content of RBC.
Lecithin cholesterol acyltransferase (LCAT)
28
Problems in Lecithin cholesterol acyltransferase (LCAT) cause?
acanthocytes
29
Carbohydrates percentage?
8%
30
Carbohydrates are supported in the RBC membrane by?
transmembrane protien
31
For determining the blood type.
Carbohydrates in RBC membrane
32
A antigen contains?
N-Acetyl-D-Galactosamine
33
B antigen contains?
D-Galactose
34
AB blood type contains?
N-Acetyl-D-Galactosamine and D-Galactose
35
O blood type contains?
none
36
Function of vertical interactions in the RBC membrane?
stabilizes the lipid bilayer membrane
37
Function of horizontal interactions in the RBC membrane?
support the structural integrity of RBC membrane
38
Vertical Anchorage?
1. TRANSMEMBRANE Proteins
2. INTEGRAL Proteins
3. Traverses across the bilipid layer
4. Band 3
5. Glycophorins (A, B, C)
39
Horizontal/Lateral Anchorage?
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
40
Membrane Proteins: Integral Proteins?
1. Band 3
2. Aquaporin
3. Glycophorin A, B, and C
41
Anion transporter.
Band 3
42
Band 3 comprises how many percent of the total protein?
27%
43
Important for the prevention of surface loss.
Band 3
44
Water transporter.
Aquaporin
45
With Colton Antigen.
Aquaporin
46
Component of aquaporin that is also present in tubules of the kidney and can determine blood type.
Colton Antigen
47
Sialic acid transporter location of MN blood group antigen.
Glycophorin A
48
Glycophorin A percentage?
85% GP
49
Ss blood group antigen.
Glycophorin B
50
Glycophorin B percentage?
45% GP
51
Gerbich blood system.
Glycophorin C
52
Glycophorin C percentage?
10% GP
53
Membrane Proteins: Peripheral Proteins?
1. Spectrin
2. Actin
3. Protein 4.2
4. Adducin
5. Ankyrin
6. Tropomyosin
7. Tropomodulin
54
Flexible, rod–like molecules responsible for biconcave shape of RBC.
Spectrin
55
Binding sites for actin filaments and protein 4.1 - forming a junctional complex.
Spectrin
56
Responsible for the contraction and relaxation of the membrane.
Actin
57
Stabilizes actin–spectrin interactions.
Protein 4.2
58
Stabilizes interaction of spectrin with actin.
Adducin
59
Adducin is influenced by?
calmodulin–actin interaction
60
A multifunctional molecule that regulates activities of a large number of proteins in the cell.
Calmodulin
61
Interacts with band 3 and spectrin to achieve linkage.
Ankyrin
62
It regulates actin polymerization.
Tropomyosin
63
It controls the actin filaments length.
Tropomodulin
64
__________ is an important property of red cell function.
Deformability
65
Red Cell Mechanics is influenced by?
* Cell shape (ratio of cell surface area to cell volume)
* Cytoplasmic viscosity (regulated by MCHC and thus cell volume)
* Membrane deformability and stability
66
Biconcave disc shape creates an advantageous _________________.
surface area/volume relationship
67
Cell shape facilitates?
deformation whilst maintaining constant surface area
68
____________________ results in biconcave shape and improved deformability.
Progressive loss of intracellular and membrane components
69
_________ will result in more spherical shape with less redundant surface area, and thus less capacity for deformability and diminished survival.
SA/V ratio alterations
70
True or false: Membrane loss = reduced SA.
True
71
True or false: Increase in cell water content = increased volume.
True
72
True or false: During pressure upon RBC, spectrin molecules undergo irreversible change in conformation: some uncoiled and extended, others compressed and folded.
False. Should be reversible.
73
During extreme or sustained pressure, membrane exhibits?
permanent “plastic” deformation
74
Deformability can be reduced by?
increases in associations between skeletal proteins or between skeletal and integral (esp band 3) proteins
75
Cytoplasmic contents of RBCs include?
* potassium ions
* sodium ions
* glucose
* intermediate products of glycolysis
* enzymes
76
Importance of Energy Metabolism?
* transport of oxygen/RBCs
* maintain activities/physical characteristics of RBCs
* survival of RBCs within 120 days
77
Embden-Meyerhof pathway utilizes _____ of RBC total glucose.
90%
78
Efficient cellular metabolism depends on?
long-lived enzymes
79
Major source of essential cellular energy.
Embden-Meyerhof pathway
80
Glucose undergoes glycolysis (glucose to lactate) to form ATPs.
Embden-Meyerhof pathway
81
Maintains pyridine nucleotides in a reduced state to permit their function in oxidation-reduction reactions within the cell.
Embden-Meyerhof pathway
82
Deficiencies in the production of ATP can be exhibited by?
* Premature cell death due to inherited defects in glycolysis
* Loss of viability during the storage of blood for transfusion
83
Number of ATP produced in Embden-Meyerhof pathway?
4
84
ATP net gain in Embden-Meyerhof pathway?
2
85
True or false: Embden-Meyerhof pathway is anaerobic.
True
86
Oxidative catabolism of glucose with reduction of NADP (nicotinamide-adenine dinucleotide phosphate) to NADPH (reduced form of NADP) which is required to reduce glutathione.
Oxidative Pathway or Hexose Monophosphate Shunt
87
Oxidative Pathway is increased with?
increased oxidation of glutathione
88
If Oxidative Pathway is defective, the amount of reduced glutathione becomes insufficient to neutralize oxidants, which causes?
denaturation of globin (Heinz bodies)
89
Oxidative Pathway or Hexose Monophosphate Shunt extends the life of RBCs by?
maintaining membrane protein, lipids, enzymes, and hemoglobin iron in reduced ferrous state
90
The only means of generating NADPH for glutathione reduction.
G6PD/Glucose-6-phosphate dehydrogenase
91
Who maintains reduced glutathione?
NADPH
92
Function of glutathione?
* reduces peroxides
* protects proteins, lipids, and heme iron form oxidation
93
Depends on Embden-Meyerhof pathway for the reduced pyridine nucleotides that keeps hgb in a reduced ferrous state.
Methemoglobin Reductase Pathway
94
Prevent the oxidation of heme iron.
Methemoglobin Reductase Pathway
95
Methemoglobin Reductase Pathway requires the reducing action of?
NADH and the enzyme methemoglobin reductase
96
Important in the oxygen-carrying capacity of RBCs.
Leubering-Rapoport Pathway
97
This mechanism is low in energy consumption.
Leubering-Rapoport Pathway
98
Capable of regulating oxygen transport even with hypoxia and acid-base disorders.
Leubering-Rapoport Pathway
99
Leubering-Rapoport Pathway permits accumulation of?
2,3 DPG / 2,3 Diphosphoglyceric Acid
100
In Leubering-Rapoport Pathway, increase in ________________ results in the binding of 2,3 DPG which stimulates glycolysis.
deoxyhemoglobin
101
Maintains cellular energy by generating ATP.
Embden Meyerhof
102
Prevents denaturation of globin of the hemoglobin molecule by oxidation.
Oxidative or Hexose-monophosphate shunt
103
Prevents oxidation of heme iron.
Methemoglobin reductase
104
Regulates oxygen affinity of hemoglobin
Leubering-Rapoport
105
loss of a portion of the erythrocytes membrane, accompanied by loss of cellular contents, including hemoglobin
Fragmentation
106
passing of water into the red cell as to ultimately burst it
Osmotic lysis
107
ingestion of whole red cells by circulating monocytes or neutrophil or by fixed macrophages of the mononuclear phagocyte system
Erythrophagocytosis
108
complement has the ability to attach itself to the cells and induce lysis
Complement induced cytolysis
109
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
Hemoglobin denaturation
110
2 Types of Destruction?
1. Intravascular hemolysis
2. Extravascular hemolysis
111
lysis of erythrocytes which occur within the circulation through the classic pathway
Intravascular hemolysis
112
It is the usual outcome of sensitization of erythrocytes with complement.
Intravascular hemolysis
113
10% of aged red cell undergo this destruction.
Intravascular hemolysis
114
Type of catabolism: Happens inside the blood vessels
Intravascular Catabolism
115
Type of catabolism: Mechanical Hemolysis & Fragmentation Hemolysis
Intravascular Catabolism
116
Type of catabolism: Happens in HEMOGLOBINOPATHIES, blood transfusion incompatibilities (destroyed before going to the spleen)
Intravascular Catabolism & Extravascular Catabolism
117
Type of catabolism: Macrophage-Mediated Hemolysis (macrophage destroys the RBC)
Extravascular Catabolism
118
Type of catabolism: Happens in senescent RBCs
Extravascular Catabolism
119
A transport protein of hemoglobin that brings hemoglobin to the liver and some to kidney.
Haptoglobin
120
A crystal that indicates intravascular hemolysis.
Hemosiderin
121
Heme absorbed into albumin forming methemalbumin and converted to Hemopexin; Heme directly converted to Hemopexin
Haptoglobin – Hemopexin – Methealbumin Salvage System
122
True or false: There should be no Heme in plasma/should be cleared in the blood stream.
True
123
Laboratory Diagnosis of Intravascular hemolysis?
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
Causes of Intravascular Hemolysis: Activation of complement on RBC Membrane?
* ABO mismatched blood transfusion
* Paroxysmal cold hemoglobinuria
* Paroxysmal nocturnal hemoglobinuria
125
Causes of Intravascular Hemolysis: Toxic Microenvironment of the RBC?
* Burns
* Snake bites
* Bacterial - Clostridium perfringens sepsis
* Parasitic infections - Plasmodium malariae
126
Causes of Intravascular Hemolysis: Physical or Mechanical Trauma to the RBC?
* Acute drug rxn in G6PD deficiency
* Mechanical heart valves
127
Causes of Extravascular Hemolysis?
* 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
