Erythrocyte Development

Question 1

Anemia is the most common disorder or the blood with 3 classes

Answer 1

excessive blood loss
excessive destruction
deficient production

Question 2

When does Hemoglobin synthesis begin?

Answer 2

Hemoglobin synthesis begins at the early erythroblast stage

Question 3

Erythropoietin

Answer 3

Acts in the bone marrow by binding to receptors on committed stem cells

Promote hemoglobin synthesis, increases membrane proteins, and causes differentiation of erythroblasts.

We can make it too!

Question 4

What is the most important function of the erythrocyte?

Answer 4

To transport hemoglobin (which is enclosed in red blood cells), which in turn carries oxygen from the lungs to the tissues

Question 5

What happens when hemoglobin formation is deficient?

Answer 5

When hemoglobin formation is deficient (as in iron deficiency for example), the percentage of hemoglobin in the cells may fall considerably, and the volume of the red cell may decrease

Question 6

Hemoglobin A

Answer 6

the normal hemoglobin
molecule found in adults

2 alpha chains + 2 beta chains => Hemoglobin A molecule

Question 7

Life Span of Erythrocyte

Answer 7

RBC is delivered from the bone marrow into circulatory system, circulates an average of 120 days before being destroyed

metabolic systems become progressively less active, and the cells become more fragile

When cell is fragile it can rupture during passage through some tight spot of the circulation

Many red cells self destruct in the spleen (spaces in the red pulp of spleen are very small, 3 micrometers wide versus 8 micrometer diameter of red cell)

Question 8

Destruction of Hemoglobin

Answer 8

RBC’s burst and release hemoglobin, the hemoglobin is phagocytized almost immediately by macrophages (especially by Kupffer cells of the liver and macrophages of the spleen and bone marrow)

Then, the macrophages release iron from the hemoglobin and pass it back into the blood, where it is carried by transferrin to either:
bone marrow for production of new red blood cells
liver and other tissues for storage in the form of ferritin

the porphyrin portion of the hemoglobin molecule is converted into the bile pigment bilirubin, which is released into the blood and later removed from the body by secretion through the liver into the bile

Question 9

Two main types of hemoglobinopathies can cause red blood cell hemolysis

Answer 9

1. Abnormal substitution of an amino acid in the hemoglobin molecule, as in sickle cell anemia
2. Defective synthesis of one of the polypeptide chains that form the globin portion of hemoglobin, as in the thalassemias

Question 10

Sickle Cell Disease

Answer 10

Results from point mutation in Beta chain of hemoglobin molecule, with abnormal substitution of a single amino acid, valine, for glutamic acid.
Sickle hemoglobin (HbS) is transmitted by recessive inheritance and can manifest as:
Sickle cell trait (heterozygote with one HbS gene)
Sickle cell disease (homozygote with two HbS genes)

Question 11

Sickle Cell Disease Pathophysiology

Answer 11

At low oxygen tension HbS becomes sickled

Sickling occurs as a result of the formation of elongated crystals inside the red blood cells (can be as long as 15 micrometers in length)

Question 12

Sickling causes two major problems

Answer 12

1. Makes it almost impossible for the red blood cell to pass through many small capillaries
2. Spiked end of crystals rupture membranes, leading to sickle cell anemia

Question 13

Acute chest syndrome

Answer 13

atypical pneumonia resulting from pulmonary infarction

Acute Chest Syndrome is a leading cause of death in sickle cell disease

Question 14

Alpha-Thalassemia

Answer 14

Impaired production of alpha globin chains, which leads to excess of beta globin chains
Asians
Synthesis is controlled by two pairs of genes
Silent carriers have a deletion of a single alpha-globin gene and are asymptomatic
Deletion of two genes (Alpha thalassemia trait)? Mild hemolytic anemia
Deletion of all 4 genes? Death

Question 15

Beta-Thalassemia

Answer 15

Impaired production of beta globin chains, which leads to a variable excess of alpha globin chains.
Most prevalent
Mediterranean anemia
One normal gene in heterozygous persons (Thalassemia minor)? => usually results in sufficient normal hemoglobin synthesis to prevent severe anemia
Homozygous persons (Thalassemia major)? => severe, transfusion-dependent anemia that is evident at 6-9 months of age

Question 16

Deficiency of G6PD

Answer 16

The disorder makes red blood cells vulnerable to oxidants and causes them to denature forming Heinz Bodies

Question 17

Carbon Monoxide

Answer 17

CO binds to hemoglobin with much greater affinity than oxygen (which is not good!), forming carboxyhemoglobin (COHb) and resulting in impaired oxygen transport and utilization

Question 18

Lead Toxicity

Answer 18

Lead is stored in bone and eliminated by the kidneys
Toxicity:
Inactivates enzymes
Competes with calcium for incorporation into the bone
Interferes with nerve transmission and brain development

Question 19

THE MAJOR TARGETS OF LEAD TOXICITY:

Answer 19

RBCs
GI tract
Kidneys
Nervous system

Question 20

Lead toxicity smear

Answer 20

RBCs smaller than normal-Increased zone of central pallor

Basophilic stippling on blood smear

Question 21

The cardinal sign of lead toxicity

Answer 21

ANEMIA
Lead competes with the enzymes required for hemoglobin synthesis

Resulting RBCs are MICROCYTIC and HYPOCHROMIC (similar to iron deficiency anemia)

Question 22

LEAD TOXICITY-SYMPTOMS / SIGNS

Answer 22

GI tract is the main source of symptoms
“Lead line”
Diffuse Kidney damage
Nervous System

Question 23

Normochromic Anemia

Answer 23

Concentration of hemoglobin in the cell is in the normal range
However, there are not enough red blood cells
Includes aplastic, post-hemorrhagic, hemolytic anemias, and anemia of chronic disease
Most frequent type of anemia

Question 24

Hypochromic Anemia

Answer 24

Red blood cells are pale
Increased central pallor
HgB is what adds the red pigment
Red Blood Cells are also usually small
Fe deficient Anemia and Thallasemia

Question 25

Microcytic Anemia

Answer 25

Small Red Blood Cells
MCV Decreased
Also, MCHC, because usually goes with hypochromic
And……Fe deficiency and Thallasemia

Question 26

Macrocytic Anemia

Answer 26

Red Blood Cells are large
Hemoglobin also down
Folate, B12, Codocytes (target cells)

Question 27

Anisocytosis

Answer 27

RBCs are of unequal size
RDW
FE DEFICIENCY ANEMIA AND THALLASEMIA

Question 28

Poikilocytosis (Erythrocytosis)

Answer 28

Abnormal shaped RBCs
Flattened disks that are thinner in the middle than at the edges
Abnormal if make up >10%
Membrane abnormalities and trauma