What are the two major differentiation tracks for hematopoietic stem cells to become white blood cells?

Myeloid lineage and lymphoid lineage

What is the function of macrophages in the immune system?

Killing pathogens by phagocytosis

Macrophages that live in tissues under normal conditions and originate in the fetal yolk sac.

Neutrophils, eosinophils, basophils

I can describe the structure and function of erythrocytes, leukocytes, and platelets in blood.

1
Most immune cells come from hematopoietic stem cells in the bone marrow, which differentiate into either the myeloid or lymphoid lineage.
2
Macrophages are phagocytic cells that ingest pathogens and cellular debris, while granulocytes like neutrophils, eosinophils, and basophils release antimicrobial chemicals.
3
Adaptive immune cells, including B cells and T cells, derive from the lymphoid lineage and provide specific immunity through antibodies and targeted cell killing.