Question

The diagram given below represents different blood cells in a smear of human blood. Answer the questions that follow-

1. Label the cells A, B, C, D, and E in the diagram.
2. Write the function of each cell.

Answer 1

1) Labeling of the diagram

1. Monocytes are the largest type of WBCs (white blood cells) that lack granules (also called agranulocytes). They have a kidney-shaped nucleus.
2. Eosinophils have a bilobed nucleus and have granules present (granulocytes).
3. Lymphocytes are spherical cells with a nucleus and a range of sizes.
4. Neutrophils are the most common type of WBCs present. They have the presence of granules (granulocytes) and have a multi-lobed nucleus.
5. Basophils are the least common type of WBCs. They have granules (granulocytes) and a bilobed or trilobed nucleus present.

2) Functions of cells in the blood

1. Erythrocytes or RBCs (red blood cells) contain hemoglobin responsible for gaseous exchange between the lungs and tissues in the body.
2. Platelets help in the formation of clots after an injury. They also secrete vasoconstrictors that help in the constriction of blood vessels. They attract WBCs to the site of injury thereby activating the immune system.
3. Monocytes enter the target tissues and become macrophages. They help in the phagocytosis of dead cells and microorganisms.
4. Lymphocytes are associated with cell-mediated immunity. They synthesize antibodies targeting pathogens and cancer cells. They are also responsible for the memory of pathogens thus facilitating efficient removal of the pathogen in future invasions.
5. Eosinophils target pathogens by releasing toxins from the granules.
6. Neutrophils use phagocytosis and superoxides to target multiple pathogens
7. Basophils are involved in mediating allergic reactions by the secretion of histamine from the granules.