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- granulocyte
- neutrophilia
- degranulation
- neutropenia
neutrophil
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What is a leukocyte?
A leukocyte, or white blood cell, is a component of the immune system that defends the body against infection and disease. Leukocytes include neutrophils, lymphocytes, monocytes, eosinophils, and basophils.
Neutrophils are a type of white blood cell (leukocyte) and granulocyte, characterized by their neutral-dye staining ability and role in immune responses against infectious microorganisms. They constitute 50 to 80 percent of all white blood cells in the human body and are often the first cells to arrive at an infection site, where they engulf and destroy microorganisms through phagocytosis.
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What is a neutrophil?
A neutrophil is a type of white blood cell (leukocyte) and a type of granulocyte. They are characterized by their ability to be stained by neutral dyes and their role in mediating immune responses against infectious microorganisms. Neutrophils are actively phagocytic, meaning they can engulf and destroy microorganisms and microscopic particles.
Neutrophils are the most common type of granulocyte, constituting 50 to 80 percent of all white blood cells in humans. They migrate to areas of infection or tissue injury, attracted by substances released at those sites. Once a bacterium is engulfed, the neutrophil's granules release enzymes and toxic forms of oxygen to destroy it. An abnormally high or low number of neutrophils can indicate certain medical conditions.
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How are neutrophils different from other types of leukocytes?
Neutrophils are a type of white blood cell (leukocyte) and a subgroup of granulocytes. Granulocytes also include eosinophils and basophils. Neutrophils are characterized by their ability to be stained by neutral dyes and their role in immune responses against infectious microorganisms. They are actively phagocytic, engulfing and destroying microorganisms and microscopic particles. Neutrophils are the most numerous of the granulocytes, making up 50 to 80 percent of all white blood cells. Unlike lymphocytes and monocytes, neutrophils have a multilobed nucleus.
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What role do neutrophils play in the immune system?
Neutrophils are vital leukocytes (white blood cells) that play a key role in the immune response against infectious microorganisms. As granulocytes, neutrophils contain granules of cell-destroying enzymes and proteins.
Neutrophils migrate to areas of infection or tissue injury, drawn by chemical substances released at the site of damage, a process called chemotaxis. They are actively phagocytic, engulfing bacteria, other microorganisms, and microscopic particles. Once a bacterium is engulfed, the neutrophil's granules release enzymes that digest the cellular material, producing hydrogen peroxide and superoxide to destroy the ingested bacteria.
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How do neutrophils help fight infections?
Neutrophils, a type of white blood cell or leukocyte, play a crucial role in the immune response against infectious microorganisms. They are actively phagocytic, meaning they can engulf bacteria, other microorganisms, and microscopic particles. When a neutrophil encounters a bacterium, it engulfs it into a phagosome. The neutrophil's granules, which are packets of digestive enzymes, then release their contents into the vacuole containing the organism, destroying it through hydrogen peroxide and other processes.
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What can happen if a person does not have enough neutrophils?
Having too few neutrophils, a type of leukocyte, is known as neutropenia. While neutropenia itself may not cause specific symptoms, it can lead to frequent and severe bacterial infections that pose a threat to life.
Neutropenia can stem from inherited disorders affecting the immune system or from acquired conditions, including exposure to harmful chemicals. Certain drugs, like those used in chemotherapy, can also cause it by damaging the bone marrow. Additionally, infections such as typhoid, HIV, or measles, as well as diseases affecting the bone marrow or spleen, can be associated with neutropenia.
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neutrophil, type of white blood cell (leukocyte) that is characterized histologically by its ability to be stained by neutral dyes and functionally by its role in mediating immune responses against infectious microorganisms. Neutrophils, along with eosinophils and basophils, constitute a group of white blood cells known as granulocytes. The granules of neutrophils typically stain pink or purple-blue following treatment with a dye. About 50 to 80 percent of all the white bloods cells occurring in the human body are neutrophils.
The neutrophils are fairly uniform in size with a diameter between 9 and 15 μm (1 μm = 0.000039 inch). The nucleus consists of two to five lobes joined together by hairlike filaments. Neutrophils move with amoeboid motion. They extend long projections called pseudopodium into which their granules flow; this action is followed by contraction of filaments based in the cytoplasm, which draws the nucleus and rear of the cell forward. In this way neutrophils rapidly advance along a surface. The bone marrow of a normal adult produces about 100 billion neutrophils daily. It takes about one week to form a mature neutrophil from a precursor cell in the marrow; yet, once in the blood, the mature cells live only a few hours or perhaps a little longer after migrating to the tissues. To guard against rapid depletion of the short-lived neutrophil (for example, during infection), the bone marrow holds a large number of them in reserve to be mobilized in response to inflammation or infection.
Within the body the neutrophils migrate to areas of infection or tissue injury. The force of attraction that determines the direction in which neutrophils will move is known as chemotaxis and is attributed to substances liberated at sites of tissue damage. Of the many neutrophils circulating outside the bone marrow, half are in the tissues and half are in the blood vessels; of those in the blood vessels, half are within the mainstream of rapidly circulating blood and the other half move slowly along the inner walls of the blood vessels (marginal pool), ready to enter tissues on receiving a chemotactic signal from them.
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Neutrophils are actively phagocytic: they engulf bacteria and other microorganisms and microscopic particles. The granules of the neutrophil are microscopic packets of potent enzymes capable of digesting many types of cellular materials. When a bacterium is engulfed by a neutrophil, it is encased in a phagocytic vacuole lined by the invaginated membrane, a structure known as a phagosome. The granules discharge their contents into the vacuole containing the organism. As this occurs, the granules of the neutrophil are depleted (degranulation). A metabolic process within the granules produces hydrogen peroxide and a highly active form of oxygen (superoxide), which destroy the ingested bacteria. Final digestion of the invading organism is accomplished by enzymes.
An abnormally high number of neutrophils circulating in the blood is called neutrophilia. This condition is typically associated with acute inflammation, though it may result from chronic myelogenous leukemia, a cancer of the blood-forming tissues. An abnormally low number of neutrophils is called neutropenia. This condition can be caused by various inherited disorders that affect the immune system as well as by a number of acquired diseases, including certain disorders that arise from exposure to harmful chemicals. Neutropenia significantly increases the risk of life-threatening bacterial infection.