Final answer:
Basophils are leukocytes that contribute to the immune response through the release of histamines and heparin. High or low basophil counts can indicate various conditions. Target and tear drop cells are abnormalities in red blood cells that signal different hematological disorders.
Step-by-step explanation:
Basophils and Blood Cell Types. Basophils are a type of white blood cell and are found in very low quantities in the blood, typically making up less than one percent of the total leukocyte count. These cells are important for the body's immune response as they release substances such as histamines and heparin, contributing to inflammation and opposing blood clotting, respectively. High levels of basophils are associated with conditions such as allergies, parasitic infections, and hypothyroidism, whereas low levels are seen in pregnancy, stress, and hyperthyroidism. Basophils are not the same as mast cells, even though they share similarities in function and were once considered to be related; they develop from different lineages.
Aside from basophils, other blood cell types include eosinophils, which combat parasitic infections, and erythrocytes (red blood cells), primarily responsible for transporting oxygen. Target cells and tear drop cells are specific forms of erythrocytes seen in certain hematological disorders. Target cells may appear in conditions such as liver disease, thalassemia or hemoglobinopathies, while tear drop cells can be indicative of severe anemias and bone marrow disorders.