White cell

White blood cells (also known as leukocytes or white cells) are the cells of the immune system that are involved in protecting the body against both infectious disease and foreign invaders. All white blood cells are produced and derived from multipotent cells in the bone marrow known as hematopoietic stem cells. They are found throughout the body, including the blood and lymphatic system.

Types of White Blood Cells

There are five main types of white blood cells, which are classified in standard systems like the Hemocytometer:

1. Neutrophils: These are the most common type of white blood cell and are first to respond to infections.
2. Lymphocytes: They are responsible for immune responses. There are two types of lymphocytes, B cells, which make antibodies that attack bacteria and toxins, and T cells, which help destroy infected or cancerous cells.
3. Monocytes: They have a longer lifespan than many white blood cells and help to break down bacteria.
4. Eosinophils: They are responsible for destroying parasites and cancer cells, and also help with allergic responses.
5. Basophils: These are the least common type of white blood cell and are responsible for inflammatory reactions during immune response, and also secrete chemical substances like histamine and heparin which help to keep the blood from clotting too quickly.

Function

White blood cells are an integral part of the body's immune response. They move in an amoeboid manner and can move through the walls of blood vessels to reach the site of an infection. They then engulf and destroy the foreign bodies or pathogens. Some white blood cells (lymphocytes) are also involved in the memory function of the immune system, 'remembering' pathogens so the body can respond quickly if the same pathogen invades again.

Disorders

Disorders of the white blood cells can be classified into too few cells (leukopenia) or too many cells (leukocytosis). These disorders can further be classified by the cause, whether it be from an outside source like radiation, infection, or drugs or from an inside source like leukemia, myeloproliferative disorders, or lymphoma.