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Liz's Hematology Module 1 > RBC Metabolism > Flashcards

RBC Metabolism Flashcards

1
Q

3 areas crucial for RBC metabolism crucial for normal survival and function

A
  1. RBC membrane
  2. Hemoglobin structure and function
  3. RBC metabolic pathways
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2
Q

2 major proteins of the RBC membrane

A
  1. Glycophorin

2. Spectrin

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3
Q

Proteins that extend from outer surface through lipid bilayer of cell membrane

A

Integral protein

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4
Q

Proteins that line the inner membrane surface to form the membrane cytoskeleton

A

Peripheral protein

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5
Q

Glycophorin

- Integral or peripheral protein?

A

Integral

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6
Q

Spectrin

- Integral or peripheral protein?

A

Peripheral

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7
Q

Major functionof glycophorin

A

Accounts for most of membrane sialic acid and gives RBC its negative charge (zeta potential); location of many RBC Ags

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8
Q

Major function of spectrin

A

Strengthens RBC membrane (shape and stability) and preserves deformability (pliability)

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9
Q

Acanthocyte

- Structural membrane defect

A

Lack of beta lipid protein

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10
Q 
Bite cell (schistocyte)
- Structural membrane defect
A

↓ spectrin (not as pliable, sluggishly travel through splenic cords); RE cells try to phagocytize them

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11
Q

Spherocytes

- Structural membrane defect

A

↓ spectrin (not as pliable, sluggishly travel through splenic cords); RE cells try to phagocytize them

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12
Q

Target cells

A

Accumulation of cholesterol in membrane

↑ surface area → ↓ intracellular hemoglobin → target cells)

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13
Q

Protein carrier that delivers iron to RBC membrane for hemoglobin synthesis

A

Transferrin

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14
Q

2 major tissues in the body where heme synthesis occurs

A
  1. Erythroid marrow (nRBCs)

2. Liver

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15
Q

Diagram sequence leading to heme synthesis beginning w/ succinyl coenzyme A + glycine and ending w/ heme

A
  1. Glycine & succinyl CoA
  2. ALA
  3. Porphobilinogen (PBG)
  4. Uroporphyrinogen
  5. Coproporphrinogen
  6. Protophorphyrinogen + Fe = protoporphyrin…to form heme
    INSERT PIC HERE
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16
Q

3 processes necessary for normal hemoglobin production

A
  1. Adequate iron delivery and supply
  2. Adequate synthesis or portoporphyrins (precursor to heme)
  3. Adequate globin synthesis
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17
Q

Overview of hemoglobin biosynthesis (nRBCs)

A
  1. Begins in mitochondria of cell
  2. Intermediate steps in cytosol
  3. Process completed in mitochondria w/ insertion of iron into protophorphyrin ring to produce heme
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18
Q

aka heme

A

Porphyrin

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19
Q

Describe the chemical structure of heme

A
  • Molecule made up of 4 pyrrole rings

- Arrangement of 4 nitrogen atoms in center enables porphyrins to chelate metal atoms (like iron)

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20
Q

Why does a patient w/ lead poisoning present “ringed sideroblasts”?

A
  • Lead blocks incorporation of iron into heme molecule

- Mitochondrial buildup of iron causes “ringed sideroblasts” → M/H anemia

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21
Q

Why is freshly voided urine from a porphyria patient not red in color?

A

It isn’t oxidized (will initially be yellow); 1 hour later will be burgundy

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22
Q

Porphyrinogen

  • Precursor to ____
  • Colorless, non-fluorescence, highly ____
  • Quickly and ____ oxidizes to ____
A

Porphyrin; unstable; irreversibly; porphyrin

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23
Q

Porphyrin

  • Stable?
  • Fluorescent?
  • Color?
A

Yes, it’s stable
Yes, it’s fluroescent
Color is pinkish-red (“port wine”) in color

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24
Q

Disorder of heme synthesis

A

Porphyria

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25
How can someone develop porphyria?
- May be inherited or acquired | - Acquired via lead poisoning or liver disease
26
Where does the abnormal accumulation of prophyrins or porphyrin precursors occur?
- Erythroid marrow | - Liver
27
3 hemoglobins found exclusively in the embryo
1. Gower 1 2. Gower 2 3. Portland
28
Hemoglobin A | - Globin chain composition and percentage of adult hemoglobin
2 alpha chains 2 beta chains > 95%
29
Hemoglobin B | - Globin chain composition and percentage of adult hemoglobin
2 alpha chains 2 delta chains 1.5-3.0%
30
Hemoglobin F | - Globin chain composition and percentage of adult hemoglobin
2 alpha chains | 2 gamma chains
31
Oxygen affinity in the relaxed form of hemoglobin
↑ oxygen affinity | - Binds to iron; as soon as one atom of iron binds to O2, three more bind causing a confirmation change
32
The relaxed form of hemoglobin is found in ____
Arterial blood
33
Another name for the relaxed form of hemoglobin
Oxyhemoglobin
34
Oxygen affinity in the tense form of hemoglobin
↓ oxygen affinity | - Results in the unloading of O2 by hemoglobin; binding of 2,3-DPG occurs
35
The tense form of hemoglobin is found in ____
Veins and tissues
36
Another name for the tense form of hemoglobin
Deoxyhemoglobin
37
What does pO2 represent on an oxygen dissociation curve?
The partial pressure or tension of oxygen in the tissues plotted against % of O2 saturation
38
On an oxygen dissociation curve, what does p50 represent?
pO2 = 26.6 mmHg when hemoglobin is 50% saturated w/ O2
39
On an oxygen dissociation curve, what is a "shift-to-the-right?"
The releasing of O2 in the tissues
40
"Shift-to-the-right" - Hb's affinity for O2 - pH - 2,3-DPG - Temperature
↓ Hb's affinity for O2 ↓ in pH ↑ in 2,3-DPG ↑ in temperature
41
On an oxygen dissociation curve, what is a "shift-to-the-left?"
O2 uptake in the lungs
42
"Shift-to-the-left" - Hb's affinity for O2 - pH - 2,3-DPG - Temperature
↑ Hb's affinity for O2 ↑ in pH ↓ in 2,3-DPG ↓ in temperature
43
3 abnormal hemoglobins taht are unable to transport or deliver oxygen
1. Carboxyhemoglobin 2. Methemoglobin 3. Sulfhemoglobin
44
Main source of ATP production in the mature RBCs
Anaerobic glycolysis in the mitochondria
45
Metabolic pathway that generates most of the RBC's ATP
Embden-Meyerhof
46
4 major RBC metabolic pathways
1. Embden-Meyerhof 2. Hexose Monophosphate Shunt 3. Methemoglobin Reductase Pathway 4. Leubering -Rapaport Shunt
47
Major function of Embden-Meyerholf pathway
Produces 90% of the energy needed by the RBC's via anaerobic glycolysis
48
Major function of hexose monophosphate shunt
Protects RBCs from environmental oxidants
49
Major function of methemoglobin reductase pathway
Maintains iron in the ferrous (2+) state in order for it to carry O2
50
Major function of Leubering-Rapaport shunt
Synthesis of 2,3-DPG
51
Changes in RBCs leading to its demise at 120 days
Senescence and then phagocytized by RES cells
52
Breakdown of senescent RBCs outside of the blood vessel w/in the cells of the RES
Extravascular hemolysis
53
Breakdown of senescent RBCs w/in the blood vessel
Intravascular hemolysis
54
___% of the destruction of senescent RBCs occurs by extravascular hemolysis
90%
55
Steps involved in extravascular hemolysis
1. RES cells phagocytize RBCs 2. Iron is coupled to transferrin and returned to BM and globin is returned to amino acid pool 3. Protophorphyrin ring of heme is disassembled and biliverdin is converted to bilirubin 5. Bilirubin is coupled to albumin and transported to liver 6. In the liver, bilirubin is conjugated to bilirubin glucuronide, converted to urobiliogen, and excreted
56
____% of the destruction of senescent RBCs occurs by intravascular hemolysis
10%
57
Steps involved in intravascular hemolysis
1. RBCs break in the lumen of vessel 2. Haptoglobin picks up free Hb 3. Hp-Hb complex goes to liver for futher catabolism...following same process as in extravascular hemolysis (do you remember it?)
58
Haptoglobin is ____ in the presence of intravascular hemolysis
Decreased
59
Why is haptoglobin decreased in the presence of intravascular hemolysis?
B/c it's busy binding up the free hemoglobin
60
What happens when haptoglobin is decreased in the presence of intravascular hemolysis?
Unbound hemoglobin dimers appear in the plasma
61
"Free heme"/unbound hemolgobin dimers in the plasma is called ____
Hemoglobinemia
62
"Free heme" is ____ by the ____ and excreted as either ____ or hemosiderin in the urine
Filtered; kidneys; hemoglobin
63
Presence of hemoglobin in the urine
Hemoglobinuria
64
T/F, under normal conditions hemoglobinemia and hemoglobinuria should be seen
False
65
Protein carrier for bilirubin
Albumin
66
Protein carrier for hemoglobin
Haptoglobin
67
Protein carrier for iron
Transferrin

Liz's Hematology Module 1 (15 decks)

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