Histology Testbank: Blood 3a

Instructions: For each histology question, pick the one best answer. This histology test bank is also useful for the histology questions on the USMLE (USMLE step 1).

1.
Which leukocyte is the second most abundant in a peripheral smear of blood?
a. Lymphocytes
b. Basophils
c. Neutrophil
d. Monocytes
e. Eosinophils

Answer: a Lymphocytes are the second most abundant leukocyte. Leukocytes are the white blood cells. The order of frequency of the leukocytes is: neutrophil, lymphocyte, monocyte, eosinophil, basophil. Histology hint fom Sarah Bellham: The order of frequency of the leukocytes can be remembered by the mnemonic: "Never Let Monkeys Eat Bananas".

2.
Which of the following is a granulocyte?
a. Lymphocyte
b. Neutrophil
c. Monocyte
d. Erythrocyte
e. Thrombocyte

Answer: b

The granulocytes are named because of the presence of visible cytoplasmic granules. The granulocytes consist of neutrophils, eosinophils, and basophils. The non-granulocytes are lymphocytes and monocytes. Erythrocytes are red blood cells. A thrombocyte is a platelet.

Histology hint from Sarah Bellham: The suffix (or prefix) "phil" comes from the Greek word meaning love. It is used to specify an attraction or affinity towards something. It is seen in such words as philosophy, philanthropy and bibliophile.

This suffix is used in naming the three granulocytes: eosinophils, basophils, and neutrophils. Eosinophils "love" or are attracted to the eosin dye; thus the granules in an eosinophil are orange/pink. Basophils "love" or are attracted to the basophilic dye; thus the granules in a basophil are blue. Neutrophils "love" or are attracted to the neutral dye; thus the granules in a neutrophil are neutral colored.

3.
Which leukocyte has orange-pink granules?
a. Neutrophil
b. Lymphocytes
c. Monocytes
d. Eosinophil
e. Basophils

Answer: d

The leukocytes consist of neutrophils, lymphocytes, monocytes, eosinophils, and basophils.

Neutrophils are granulocytes. Neutrophils have a multi-lobed nucleus. The lobes are separated by a thin strand. Because of the shape of the nucleus, neutrophils are also called "polymorphonuclear neutrophils", "poly's", "PMN", or "polymorph".

Lymphocytes are agranulocytes. Lymphocytes can be categorized by three sizes: small, medium, and large. The small lymphocytes are the smallest leukocyte, being only slightly larger than an erythrocyte.

Monocytes are agranulocytes. They are the largest leukocyte.

Eosinophils are granulocytes. Eosinophils have prominent orange pink granules. The nucleus of eosinophils is usually bi-lobed.

Basophils are granulocytes. Basophils have large blue granules, which often obscure the nucleus. The granules are basophilic, therefore they are blue.

4.
What is another term for a red blood cell?
a. Thrombocyte
b. Monocyte
c. Lymphocyte
d. Basophil
e. Erythrocyte

Answer: e

An erythrocyte is another name for a red blood cell.

5.
Which of the following is described as a "biconcave disc"?
a. Platelets
b. Erythrocytes
c. Leukocytes
d. Monocytes
e. Eosinophils

Answer: b

Erythrocytes (red blood cells) are described as biconcave discs. When stained, this phenomenon results in the central portion of the cell staining lighter, thus the "central pallor".

Histology hint from Sarah Bellham: A biconcave disc can be visualized by holding two Frisbees together so that the middle portion is thinner than the top or bottom.

6.
Which is the largest leukocyte?
a. Neutrophil
b. Lymphocytes
c. Monocytes
d. Eosinophil
e. Basophils

Answer: c

The leukocytes consist of neutrophils, lymphocytes, monocytes, eosinophils, and basophils.

Neutrophils are granulocytes. Neutrophils have a multi-lobed nucleus. The lobes are separated by a thin strand. Because of the shape of the nucleus, neutrophils are also called "polymorphonuclear neutrophils", "poly's", "PMN", or "polymorph".

Lymphocytes are agranulocytes. Lymphocytes can be categorized by three sizes: small, medium, and large. The small lymphocytes are the smallest leukocyte, being only slightly larger than an erythrocyte.

Monocytes are agranulocytes. They are the largest leukocyte.

Eosinophils are granulocytes. Eosinophils have prominent orange pink granules. The nucleus of eosinophils is usually bi-lobed.

Basophils are granulocytes. Basophils have large blue granules, which often obscure the nucleus. The granules are basophilic, therefore they are blue.