Leukocytes

What Are Leukocytes (White Blood Cells)?

Leukocytes are more popularly known as white blood cells (WBCs). They form an integral part of the immune system and play a very important role in body defence against infections, foreign invasions, and diseases. In contrast to erythrocytes, leukocytes are not restricted to the blood. They move in and out of blood vessels into the tissues to perform their functions wherever necessary.

Structure Of Leukocytes

• Nucleus: Unlike erythrocytes, the leukocyte does have a nucleus. It is considered an essential component because, without a nucleus, the leukocytes would not have the ability to function and reproduce.

• Cytoplasm: The cytoplasm has many granules that assist in performing their immune functions.

• Cell Membrane: The cell membrane is semipermeable and pliable. This allows the leukocyte to change shape and move through tissue.

Types Of Leukocytes

There are two general types of leukocytes:

• Granulocytes: These include neutrophils, eosinophils, and basophils. They have granules in the cytoplasm and are involved in inflammatory reactions and protection from infection.

• Agranulocytes: They are made of lymphocytes and monocytes. They play a part in specific immune responses and antibody production.

Functions Of Leukocytes

• Defence Against Infections: Leukocytes recognize the disease-causing organisms like bacteria, viruses, and fungi, and destroy them.

• Immune Response Regulators: They act as immune response regulators by displaying signals that communicate with other immune cells and instruct them in their actions.

• Inflammation: The inflammatory response in which leukocytes take part helps to isolate and clear the pathogenic agents.

Role Of Neutrophils :

• Neutrophils are the most common granulocytes and can often be the first to arrive at the site of infection.

• They internalize and digest pathogens through the process of phagocytosis.

• Their rapid response and capacity for creating reactive oxygen species make them critical during the early natural phase of immune defence.

Role Of Lymphocytes

Lymphocytes play a central role in adaptive immunity. There are two major types:

• B Lymphocytes: These cells produce antibody proteins that recognize specific pathogens.

• T Lymphocytes: These cells can, in a process called apoptosis, directly kill infected cells, or they help to control the immune response.

Role Of Monocytes

• Monocytes are large WBCs that mature into macrophages and dendritic cells when they enter tissues.

• As mentioned earlier, macrophages phagocytize and present antigens to T lymphocytes.

• Dendritic cells also present antigens to T lymphocytes.

• Furthermore, dendritic cells sitios activate the adaptive immune response.

Leukocyte Production

• Hematopoiesis: Leukocytes develop in the bone marrow via a process known as hematopoiesis that entails the differentiation of hematopoietic stem cells.

• Lifespan: The life span of leukocytes is pretty variable. For example, neutrophils may live from a few hours to a few days and memory lymphocytes might persist even for years.

Disorders Of Leukocytes

• Leukaemia: It is a kind of cancer that is marked by the uncontrolled multiplication of abnormal leukocytes.

• Leukopenia: A low count of white blood cells; increases the susceptibility to infections.

• Lymphoma: A cancer of the lymphatic system that affects lymphocytes.

Role Of Leukocytes In Health

• Leukocytes are essential in maintaining good health.

• The cells help in fighting infections and diseases.

• Because of their ability to amend their shape and phagocytose most pathogens, they become part of the immune system.

• WBC count may, in turn, be observed to give a related fact about one's health status.

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