Production of NADPH using G6PD

Reduces glutathione to active form

Protection from oxidation

In steady-stage glycolysis, 5-10% of G6P is diverted to this pathway. During oxidative challenge, the activity of this shunt may increase by up to 30-fold.

Ø H2O2 oxidizes heme iron to the nonfunctional ferric state and oxidizes and denatures proteins and lipids

G6PD provides the only means of generating NADPH for glutathione reduction, and in its absence, RBCs are particularly vulnerable to oxidative damage.

The HMP pathway is not able to reduce methemoglobin once it forms.

Ø The reduction of methemoglobin by NADPH is rendered more efficient in the presence of methemoglobin reductase, also called cytochrome-b5 reductase.

This shunt generates 2,3- bisphosphoglycerate (2,3- BPG), also called 2,3- diphosphoglycerate.

2,3 BPG production

Methemoglobin reduction

NADPH generation

Normal fraction of central pallor

Hemoglobin is composed of .. heme

Hemoglobin is composed of .. globin

Alpha

Zeta

Epsilon

Gamma

Delta

Beta

2 Zeta + 2 Epsilon chains

2 Alpha + 2 Epsilon chains

2 Zeta + 2 Gamma chains

2 Alpha + 2 Gamma chains

Begins in early embryogenesis; peaks during third trimester and declines before birth.

Approximately .. mL of O2 is bound by each gram of hemoglobin

2,3-BPG formation (oxygen release to tissues)

Shift to the right (O2 dissociation curve)

Converts ferric iron to ferrous iron

Characterized by cherry-red blood discoloration.

Absorbance at 540 nm:

Caused by exposure to carbon monoxide (CO) which has a 240 times aainity for hemoglobin than that of oxygen.

At 20-30%, toxic effects such as headache, dizziness, disorientation begin to appear.

At levels >40%, coma, seizure, hypotension, cardiac arrhythmia, pulmonary edema, and death may occur

Absorbance at 630 nm:

Formed by the reversible oxidation of heme iron to the ferric state (Fe3+).

High level of methemoglobin is associated with a chocolate brown blood discoloration that does not revert back to a normal red color after exposure to oxygen.

The NADH-cytochrome b5 reductase 3 is a pathway that limits the accumulation of methemoglobin to only 1%.

EUects: Ø <25%: Asymptomatic Ø >30%: Cyanosis, symptoms of hypoxia Ø >50%: Coma, death

Exogenous oxidants such as nitrites, primaquine, dapsone, or benzocaine can cause methemoglobinemia in the acquired form.

Formed by the irreversible oxidation of hemoglobin by drugs (i.e. sulfanilamides, phenacetin, nitrites, phenylhydrazine) or exposure to sulfur chemicals in industrial or environmental settings.

A sulfur atom is added to the pyrrole ring of heme and has a characteristic greenish pigment.

Despite having a similar peak with hemoglobin on a spectral absorption instrument, what diUerentiates sulfhemoglobin is that it does not shift when cyanide is added.

Characterized by a greenish tinge or mauve lavender discoloration of the blood

Does not revert back to normal color upon exposure to oxygen

Caused by irreversible oxidation of heme iron to its ferric form

By sulfanilamides, phenacetin, nitrites, phenylthydrazine, or exposure to sulfur chemicals in industrial or environmental settings

Contains iron actively functioning within cells, such as in hemoglobin, myoglobin, cytochromes, and enzymes.

Iron in the ferrous form (Fe2+).

Iron that is not actively functioning, but available for future use.

Stored mainly in hepatocytes, macrophages of the spleen and bone marrow, and in some amount in every cell except mature RBCs. se.

Iron in transit between body sites via plasma.

Iron in the ferric form (Fe3+).

Iron-free forms of transferrin and ferritin, respectively, with apotransferrin lacking bound iron and apoferritin empty of iron in its core.

Iron-loaded versions, with holotransferrin bound to iron in transit and holo-ferritin storing iron within its core for later use.

What is the most commonly used blood collection tubes in the Hematology section?

The anticoagulant-to-blood ratio for a light blue-top is

If a blood film is not stained within 2 hours, what background color will it give on a Wright's stain?

Proper application of tourniquet:

Cleansing of the venipuncture site should be in a ________ motion

Finger puncture should be done ___ to the fingerprint

Which of the following should be the last to be filled when collecting blood from skin puncture?

During the 5th to 7th gestational weeks, what is the main site of hematopoiesis?

After retrogression, active marrow is restricted to the following bones, except:

The following cells temporarily decreases after splenectomy except:

Which of the following is true regarding early hematopoietic stem cells (HSCs)?

Which of the following follows the general trends in the appearance in erythropoiesis?

Detectable hemoglobin synthesis occurs in the:

The pink color associated with stained hemoglobin is seen in which of the following stages?

The orthochromatic erythroblast stage is the last stage of ___ synthesis

The RBC lifespan in a term neonate is:

Which RBC membrane lipid has an increased distribution on the outer layer of senescent RBCs and serves as a receptor that macrophages bind to, leading to increased RBC death?

The M & N antigens are located in which glycophorin?

Production of 2,3-disphosphoglycertae occurs in which glycolysis diversion pathway?

A ring of carbon, hydrogen, and nitrogen atoms with a central atom of ferrous iron

Heme biosynthesis begins in the ___ and ends in the ___ of erythroid precursor cells

Which globin chain is coded on the short arm of chromosome 16?

In a normal adult, the composition of hemoglobin from the greatest to least is:

At birth, which composition of hemoglobin is predominant?

It is formed by the irreversible oxidation of hemoglobin by drugs or exposure to chemicals in industrial or environmental settings

The effect of hepcidin to the amount of serum iron: