03b: RBC Flashcards
List some things transported by blood.
- Water
- Heat
- Gasses
- Defense components
- Proteins
- Nutrients/salt/waste
- Messengers (hormones)
Amount of blood per kg BW in male and female.
Male: 75 mL/kg
Female: 65 mL/kg
How many liters blood in average person?
5-6 L
Clinically, one “unit” of blood is what volume?
450 mL
Concentration of Hb in a RBC:
30g/dL RBC
Why is Hb packaged in RBC?
Has short half-life in circulation
RBC is about (X) thick and has a diameter of (Y).
X = 1-2 micrometers Y = 8 micrometers
What can occur to RBCs in slow-flowing blood?
Form rouleaux (stack together like roll of coins)
RBC rouleaux more seen in which cases?
- Diseases that increase RBC stickiness (change surface proteins)
- Pregnancy
T/F: RBC transports lots of oxygen, but does not use it.
True
RBC mitochondria produce ATP at (slower/faster) rate than other cells.
No mitochondria! Only ATP production by anaerobic glycolysis
If an RBC is depleted of ATP:
Shape changes (crenated)
Glucose enters RBC via which transporter(s)?
None; just by simple diffusion
Why/how does crenation of RBC happen?
- ATP depletion
- Dysfunction of Na/K and Ca pump
- Ca accumulates in cell (spiky appearance)
Sickle cell disease arises from:
One AA change in Hb
Which conditions begin the sickle cell crisis? Why?
Low oxygen or low pH; causes HbS to crystallize into long, rigid rods (gives cell sickle shape)
Why is a sickle shape problematic?
Cells not flexible, block vasculature, decrease oxygen and increase LA buildup (cycle)
Methemoglobin is (X) and functions to (Y).
X = oxidized form of Hb (has ferric ion)
Non-functional!
Oxidized Hb transforms into:
Dysfunctional Hb (methemoglobin)
T/F: oxidation of Hb is reversible.
True
(X) restores the iron to (Y), making Hb functional again.
X = methemoglobin reductase Y = ferrous state (Fe2+)
RBC requires NADH because it acts as a(n) (X) for (Y).
X = cofactor Y = methemoglobin reductase
NADH levels in RBC maintained by:
Glycolysis
Why is it important to maintain adequate H2O2 levels in RBC?
It’s not… H2O2 is potent oxidizing species for Hb
What’s the effect of H2O2 on RBC?
Cross-links Hb cysteines (inactivated protein)
H2O2 levels in RBC are kept in check by:
Reaction with reduced GSH (glutathione)
H2O2 + GSH equals…
Glutathione-peroxidase,
which then becomes oxidized glutathione and water
Reduced GSH levels are kept in check by:
Glutathione reductase
RBC requires NADPH because it acts as a(n) (X) for (Y).
X = cofactor Y = glutathione reductase
NADPH levels in RBC are kept in check by:
G6PD (in phosphogluconate pathway)
Deficiency in (NADH/NADPH) can cause (X) anemia.
NADPH;
X = hemolytic
The Luebering-Rapoport pathway is an off-shoot of (X). It’s important in producing (Y) for RBC.
X = glycolysis Y = 2,3-DPG
What’s the effect of 2,3-DPG in RBC?
Changes Hb affinity for oxygen (binds it less tightly if 2,3-DPG present)
Formation of RBCs in fetus is dependent on:
Yolk sac (liver and spleen) and bone marrow
Describe role of kidney in RBC formation.
RBC formation increased if low oxygen levels detected by JG Apparatus; kidney will secrete more EPO
Iron used to synthesize Hb comes from:
- Old RBC (mainly)
- Body stores
- GI tract
Old RBCs are taken up by (X). This occurs mostly in which organ? Why?
X = macrophages
Spleen - finest sieve in entire body and old RBC lose flexibility/can’t pass
Most RBC meet their end by:
Extra-vascular hemolysis
Macrophage breaks down Hb into which main components?
- Globin
- Fe
- Porphyrin ring
In extravascular hemolysis, what’s the fate of globin?
Recycled into AA pool
In extravascular hemolysis, what’s the fate of Fe?
Recycled by immediately binding Transferrin (which will take it to developing RBC)
In extravascular hemolysis, what’s the fate of porphyrin ring?
Can’t be recycled, so converted to bilirubin
In extravascular hemolysis, what’s the fate of bilirubin?
- Binds plasma albumin
- taken to hepatocyte
- secreted in feces as urobilinogen
What’s the first step in intravascular hemolysis?
- Immediate oxidation of Hb to methemoglobin
2. Breakdown of tetramer to Hb dimer
In intravascular hemolysis, what’s the fate of methemoglobin?
Breaks down into globin and heme
In intravascular hemolysis, what’s the fate of heme?
Binds hemopexin and carried to liver
In intravascular hemolysis, what’s the fate of Hb dimer?
- Binds haptoglobin and carried to liver
2. If haptoglobin all full, goes straight to kidney and secreted in urine
In intravascular hemolysis, what’s the function of liver?
Takes either Hb dimer or heme and breaks them down into Fe and bilirubin (eventually secreted in feces)
Why/when does our body produce CO?
Extravascular hemolysis; conversion of porphyrin ring to bilirubin in macrophage releases CO
What are the clinical methods to test for (extra/intra)-vascular hemolysis? About how long is each test valid following event?
Intravascular;
- Test for low haptoglobin levels (up to 5 days)
- Hemoglobinuria; Test for presence of Hb in urine (up to 2 days)
Why would inflammation cause hypoproliferative anemia?
Fe released by RBC death are taken up by bacteria, so low Fe content
Too few (X) can cause anemia.
X = RBC or Hb
Most common reason behind anemia is:
Hypoproliferation (production is too slow)
Hemolysis refers to:
Abnormally rapid destruction of RBC
In blood typing, the concern is agglutination of (donor/recipient/both) blood.
Donor (Ab in donor blood very dilute so they have no effect on recipient)
Cell with D antigen are termed:
Rh-positive
Describe the relationship between (deficiency/excess) of Vitamin (X) and (Y) anemia.
Deficiency;
X = B12
Y = hypoproliferative/pernicious
Condition leads to large-scale destruction of erythrocyte precursors
In (X) anemia, intestinal absorption is compromised due to failure of (Y) cells to (Z).
X = pernicious Y = parietal cells (in stomach) Z = produce intrinsic factor
Vitamin (X) is critical in which stage of RBC development?
X = B12 (and folic acid)
Proliferation of erythrocyte precursors in bone marrow
Renal disease can cause (X) anemia because of (Y) (destruction/production).
X = hypoproliferative
X = inadequate erythropoietin production
Thalassemia can be a cause for (X) anemia due to (Y) (destruction/production)
X = hypoproliferative
Y = abnormal Hb synthesis (and thus destruction of RBC precursors in marrow)
