White blood cells are also known as leukocytes. They are an essential component of the immune system and play a crucial role in protecting the body against infections and diseases. White blood cells are produced in the bone marrow and are present in the blood and lymphatic system.

Types of White Blood Cells:
White blood cells can be classified into several types, each with its own unique function and characteristics. The main types of white blood cells include:

1. Neutrophils: Neutrophils are the most abundant type of white blood cells and make up about 60-70% of the total white blood cell count. They are the first responders to infections and are highly effective at engulfing and destroying bacteria and other pathogens.

2. Lymphocytes: Lymphocytes are the second most common type of white blood cells. They are further divided into subtypes, including T cells, B cells, and natural killer (NK) cells. Lymphocytes are responsible for immune responses, such as recognizing and attacking specific foreign substances and producing antibodies.

3. Monocytes: Monocytes are larger white blood cells that are capable of differentiating into macrophages and dendritic cells. They play a vital role in engulfing and digesting foreign particles, dead cells, and debris.

4. Eosinophils: Eosinophils are involved in the defense against parasites and are also associated with allergic reactions. They release toxic substances to destroy parasites and modulate allergic responses.

5. Basophils: Basophils are the least common type of white blood cells. They are involved in allergic reactions and release substances like histamine, which promotes inflammation.

Functions of White Blood Cells:
White blood cells are responsible for various functions within the immune system, including:

1. Phagocytosis: Neutrophils, monocytes, and macrophages are capable of engulfing and digesting pathogens, dead cells, and debris through a process called phagocytosis.

2. Antibody production: Lymphocytes, particularly B cells, play a crucial role in producing antibodies. These antibodies recognize and bind to specific antigens, marking them for destruction by other immune cells.

3. Cellular defense: Lymphocytes, such as T cells and NK cells, are involved in direct cell-mediated immune responses. They can recognize and destroy infected or abnormal cells.

4. Regulation of immune responses: White blood cells release various chemical messengers, called cytokines, which help regulate and coordinate immune responses.

In conclusion, white blood cells, or leukocytes, are a diverse group of cells that are vital for the functioning of the immune system. They perform different functions, including phagocytosis, antibody production, cellular defense, and regulation of immune responses. Understanding the role and types of white blood cells is crucial in comprehending the body's defense mechanisms against infections and diseases.

Leucocytes