TBL 12: Blood Smears/Blood

Question 2

How is a blood smear performed?

Answer 2

A blood smear is performed by evenly spreading a drop of blood across a glass slide to create a thin film. This smear is then stained with eosin (orange-red to pink dye), basica dyes (dark blue dye), and neutral dyes (faint pink) which enables distinction of the blood cells.

Question 3

What are the typical staining colors of RBCs and nucleiof leukocytes, respectively?

Answer 3

RBCs typically stain orange-red to pink.

Nuclei of leukocytes typically stain dark blue.

Question 4

Explain the rationale behind the names:

a) eosinophils
b) basophils
c) neutrophils

Answer 4

a) eosinophils stain orange-red to pink (eosin dye)
b) basophils stain dark blue (basic dye)
c) neutrophils stain faint pink (neutrophils)

Question 5

Arrange the following leukocytes in order of most common to least commonly seen in normal blood smears:

• monocytes, neutrophils, basophils, lymphocytes, eosinophils.*

Answer 5

Most common

1) neutrophils

2) lymphocytes

3) monocytes

4) eosinophils

5) basophils

Least common

Question 6

What are the respective fractions of the following cells within blood:

hematocrit, leukocytes and platelets, plasma

Answer 6

Question 7

What characterizes neutrophils?

What are other names for neutrophils?

Answer 7

Neutrophils are characterized by multibulated nucleie and fin cytoplasmic granules.

Others names are polymorphonuclear leukocytes, PMNs, polys, and polymorphs.

Question 8

How long do leukocytes remain in the circulation?

Answer 8

Leukocytes remain in the circulation for only a few days before taversing the capillary endothelium into the interstitial fluid of the surround connective tissue.

Question 9

What is anemia and why can a loss of central pallor indicate sickle cell anemia?

Answer 9

Anemia is a deficiency of RBCs and/or hemoglobin.

Since RBC’s are usually biconcave, the central portion is usually the thinnest portion and therefore has relatively less hemoglobin so less staining occurs here. In sickle cell anemia, there is loss of this biconcave shape, thus loss of the central pallor.

Question 10

What conditions cause neutrophilia and neutropenia?

Answer 10

Neutrophilia (increase in neutrophil numbers) occurs in acute bacterial infections.

Neutopenia is an abnormal decrease in neutrophil numbers often caused by genetics, drugs, or autoimmune diseases such as AIDS.

Question 11

What is a “shift to the left” that can occur with bacterial infections?

Question 12

What is the function of eosinophils and how do they affect the functions of mast cells and basophils?

Answer 12

Eosinophils phagocytose antigen-antibody complexes and parasites. They secrete histaminase which inactivates histamine produced by basophils and mast cells.

Question 13

Which primary conditions induce eosinophilia?

Answer 13

Mainly parasitic infestations, allergic reactions, and some malignancies.

Question 14

How is mild and severe basophilia distinguished?

Answer 14

There is a larger increase in severe basophilia..

Question 15

Contrast monocytes and lymphocytes.

Answer 15

Monocyte nuclei are highly indented and less densely stained than that of lymphocytes

Question 16

What are monocytes?

Answer 16

monocytes are precursor cells that enter the interstitial fluid to become macrophages during acute inflammatory responses.

Question 17

When does lymphocytosis occur in infants and adolescents, and what is infectious mononucleosis?

Answer 17

Lymphocytosis is an abnormal increase in absolute number of lymphocytes in peripheral blood. It often occurs in infants and adolescents during infections that would likely produce a neutrophil response in adults.

Infectious mononucleosis is a rise in circulating T lymphocyte numbers in response to Epstein-Barr viral infection of B cells. Lymphocytes are larger than normal and look atypical.

Question 18

Why does monocytosis occur with chronic infections such as bacterial endocarditis?

Answer 18

Monocytosis is an abnormal rise in the monocyte count. This is common with chronic infections because large numbers are found in areas of inflammation where they engage in phagocytosis and scavenging of cell debris.

Question 19

What are platelets?

Answer 19

Platelets (thrombocytes) are tiny cytoplasmic fragments, visible in blood smears only when they cluster into larger clumps. These are related to blood clot formation.

Question 20

What is the largest hemopoietic cell in the bone marrow and what does it do?

Answer 20

Megakaryocytes are the largest hemopoietic cell in the bone marrow and after being stimulated by thrombopoietin, it forms platelets through organized cytoplasmic fragmentation.

Question 21

What causes thrombocytopenia?

Answer 21

Thrombocytopenia is a condition involving abnormal depletion of platelets in blood. It may be caused by failure of bone marrow to produce adequate numbers of platelets or by a greater rate of removal of platelets from blood.

Question 22

Why are brusing, infections, and lethargy associated with aplastic anemia?

Answer 22

Aplastic anemia is a hematologic disorder caused by bone marrow failure. It is usually dfined as pancytopenia, or a reduced count of all major blood cells of the erythroid and myeloid series.

Bruising occurs because lack of platelets, infections occur because lack of immune cells, lethargy because lack of RBCs carrying oxygen.

Question 23

What is a “shift to the left” that can occur with bacterial infections?

Answer 23

Normally with no infection present, you will see more mature immune cells in the blood (the right side of the spectrum). However with an infection, the bone marrow pumps out immature immune cells *(left side of the spectrum) *called bands which will then differentiate into either eosinophils, basophils, or neutrophils.