01 LEC: Erythrocyte metabolism & membrane structure Flashcards
Glucose enters the RBC by facilitated diffusion via the transmembrane protein ___
Glut-1
The ___ is an anaerobic pathway that generates ATP
Embden Meyerhof Pathway
The enzyme deficiency present for defective Embden Meyerhof Pathway
Pyruvate kinase deficiency
The hexose monophosphate shunt is also called
Pentose phosphate shunt
The hexose monophosphate shunt provides ___ and ___
reduced glutathione and NADPH
Enzyme deficiency for defective hexose monophosphate shunt
glucose-6-phosphate dehydrogenase deficiency
G6PD deficiency causes ___ ___ anemia
episodic hemolytic
In G6PD, the denatured hgb produces ___
Heinz bodies
Where can we see presence of bite cells/pitted cells?
G6PD deficiency
T/F: bite cells can be seen using wright stain
T
RBC components that can be seen through supravital staining
Reticulocyte
Heinz bodies
Hemoglobin H
The methemoglobin reductase pathway is also called ___
cytochrome b5 reductase
The methemoglobin reductase pathway is able to ___ ___ once it forms
Reduce methemoglobin
T/F: NADPH is more efficient in reducing methemoglobin than cytochrome b5
F
This pathway generates 2,3-bisphosphoglycerate
Rapoport-Luebering pathway
Importance of 2,3-DPG/BPG in the erythrocyte metabolism
Expels out O2 from the hemoglobin
The binding of 2,3-DPG/BPG shifts the hemoglobin-oxygen dissociation curve to the ___, which enhances delivery of oxygen to the tissues
right
RBC membrane components
CHO 10%
Protein 50%
Lipid 40%
RBC membrane phospholipids are ___ distributed
asymmetirically
___ and ___ predominate in the outer layer of RBC membrane
phosphotidylcholine
sphingomyelin
___ and ___ predominate in the inner layer of RBC membrane
phosphatidylserine
phosphatidylethanolamine
This is described as regularly spaced projections present in a cell
echinocyte/burr cell
This is described as large, irregular projections present in a cell
acanthocytosis/spur cell
___ and ___ are associated with abnormalities in the concentration or distribution of membrane cholesterol and phospholipids
acanthocytosis and target cells
transmembrane and cytoskeletal proteins make up ___ of the half of the RBC membrane structure by mass
52%
This serve many functions, including transport sites, adhesion sites, and signaling receptors
transmembrane proteins
Identify the transmembrane protein:
water transporter, colton antigen
aquaporin 1 (AQP1)
Identify the transmembrane protein:
anion transporter, location of ABH antigens
Band 3 (SLC4A1)
Identify the transmembrane protein:
G protein-coupled receptor, chemokine receptor, Duffy antigens, receptor for malarial parasites
Duffy (FY, DARC, ACKR1)
Identify the transmembrane protein:
Glucose transporter, location of ABH blood group antigens
Glut-1 (SLC2A1)
Identify the transmembrane protein:
Sialic acid transporter, location of MN blood group antigens
Glycophorin A (GYPA)
Identify the transmembrane protein:
Sialic acid transporter, location of Ss blood group antigens
Glycophorin B (GYPB)
Identify the transmembrane protein:
Sialic acid transporter, location of Gerbich system antigens
Glycophorin C (GYPC)
Identify the transmembrane protein:
Zn binding endopeptidase
Kell (KEL)
Identify the transmembrane protein:
Urea transporter
Kidd (SLC14A1)
Identify the transmembrane protein:
D and CcEe antigens; stabilizes band 3 and Rh macrocomplexes
Rh (RHCE, RHD)
Located in membrane macromolecular complexes that serve as transporters, structural components, enzymes, receptors, and adhesion molecules
Blood group antigens
___ and ___ support the majority of ABH system
Band 3 & Glut-1
Glycophorins C & D carry the ___
Gerbich system antigens
Loss of the RhAG glycoprotein (Rh-null) prevents expression of both the D and CcEe antigens and is associated with RBC morphologic abnormalities such as ___
stomatocytosis
A few copies of the ___ ___ reside in the outer, plasma-side layer of the membrane, which serves as a base on which a glycan core of sugar molecules is synthesized
phospholipid phosphatidylinositol (PI)
PI serves as a base for a glycan core to synthesize ___
glycosylphosphatidylinositol (GPI) anchor
They protect the RBC membrane from lysis by complement
GPI anchored proteins
The GPI anchored proteins include:
Decay-accelerating factor (CD55)
Membrane Inhibitor of Reactive Lysis (MIRL or CD59)
An acquired mutation of PIGA genes affect the cells and make them susceptible to ___ ___
complement-mediated hemolysis
The principal cytoskeletal proteins are the filamentous ___ and ___
a-spectrin and b-spectrin
They arise from defects in spectrin or proteins forming the ankyrin complex that provide vertical support for the membrane
hereditary spherocytsosis
They are due to defects in cytoskeletal proteins that provide horizontal support for the membrane
hereditary elliptocytosis
Identify the cytoskeletal protein:
filamentous antiparallel heterodimer, primary cytoskeletal proteins
a-spectrin
b-spectrin
Identify the cytoskeletal protein:
Anchors band 3, protein 4.2, and other proteins
Ankyrin
Identify the cytoskeletal protein:
Anchors the actin junctional complex to spectrin tetramers, RBC cytoskeleton shape
Protein 4.1
Identify the cytoskeletal protein:
Part of ankyrin complex, ATP binding protein
Protein 4.2
Heme is composed of ___ and ___
Protoporphyrin IX and Fe2+
Heme synthesis begins in the ___ with the formation of ___
mitochondria
ALA
___ portion gives RBC their characteristic red color
heme
Chromosome __ codes for Alpha and Zeta
16 (short arm)
Chromosome __ codes for Beta, Gamma, Delta, and Epsilon
11 (short arm)
The primary hemoglobin until 6 months of age
HgbF
This factor binds in the B-gene promoter region
Kruppel-like factor 1 (KLF-1)
T/F: during oxygenation, each one of the four heme iron atoms in a hemoglobin molecule irreversibly bind one O2 molecule
F (reversible)
Approximately ___ of oxygen is bound by each gram of hemoglobin
1.34 mL
Normally, a PO2 of approximately ___ results in 50% O2 saturation
27 mmHg
A shift in the curve because of a change in pH
Bohr effect
During __ state, there is low affinity to oxygen and it is less likely to bind to O2 molecules
tensed (right shift)
During __ state, the blood is in deoxygenated form
tensed (right shift)
The __ state is stabilized by a network of salt bridges and hydrogen bonds between subunits
tensed (right shift)
The tensed state is more stable in condition of __ pH and __ conc of 2,3-DPG
low, high
During __ state, hemoglobin has a higher affinity for oxygen
relaxed (left shit)
During __ state, the hemoglobin is typically in its oxygenated form
relaxed (left shift)
During relaxed state, binding of O2 disrupts the ___ and ___ that stabilized the t state
salt bridges
hydrogen bonds
This is formed by reversible oxidation of heme iron to the ferric state
methemoglobin
Occurs after exposure to exogenous oxidants such as nitrites, primaquine, dapsone, benzocaine
Acquired/toxic methemoglobin
30-50% methemoglobin, structurally abnormal polypeptide chain that favors the oxidized ferric form of iron and prevent its reduction
M hemoglobin/ HbM
Levels of methemoglobin and its interpretation
<25% asymptomatic
>30% cyanosis, hypoxia (needs IV methylene blue)
>50% coma and death
Methemoglobin causes ___ discoloration of blood
chocolate brown
Methemoglobin is detected at ___ nm spectral absorption
630 nm
The treatment for methemoglobin is ___
methylene blue
Irreversible oxidation of hgb by materials containing sulfur or exposure to sulfur chemicals
sulfhemoglobin
Addition of sulfur atom to pyrrole ring results to ___ pigment
greenish
Sulfhemoglobin is also reported in px with severe constipation in cases of bacteremia due to ___
C. perfringens
T/F: Sulfhemoglobin is reversible and can be converted back to adult hemoglobin
F (persist for the life of the cell :(()
Sulfhemoglobin causes ___ discoloration of blood
mauve lavender
Methemoglobin is detected at ___ nm spectral absorption
630
Cyanmethemoglobin is detected at ___ nm spectral absorption
540
Cyanmethemoglobin measures all forms of hgb except ___
sulfhemoglobin
Combination of CO with heme iron
Carboxyhemoglobin (COHb)
In COHb, the affinity of CO is ___x that of oxygen
240 (200)
__ has been termed as the silent killer, because it is an odorless and colorless gas, and victims may quickly become hypoxic
CO
Diagnosis of CO poisoning is made if the COHb levels is ___ in nonsmokers and ___ in smokers
3%
10%
How many % til COHb symptoms appear?
20-30%
How many % til COHb cause coma, seizure, or death?
> 40%
COHb causes ___ discoloration of blood
cherry red color (skin also !)
COHb is detected at __ nm spectral absorption
540
Treatment for COHb
hyperbaric oxygen therapy
