What is the term for cell movement through blood vessels to a tissue site
|
While every effort has been made to follow citation style rules, there may be some discrepancies. Please refer to the appropriate style manual or other sources if you have any questions. Show Select Citation Style Copy CitationShare Share Share to social media Facebook Twitter URL https://www.britannica.com/science/neutrophilGive Feedback External Websites Feedback Corrections? Updates? Omissions? Let us know if you have suggestions to improve this article (requires login). Feedback Type Thank you for your feedback Our editors will review what you’ve submitted and determine whether to revise the article. External Websites
Print Cite verifiedCite While every effort has been made to follow citation style rules, there may be some discrepancies. Please refer to the appropriate style manual or other sources if you have any questions. Select Citation Style Copy CitationShareShare Share to social media Facebook Twitter URL https://www.britannica.com/science/neutrophilFeedbackExternal Websites Feedback Corrections? Updates? Omissions? Let us know if you have suggestions to improve this article (requires login). Feedback Type Your Feedback Submit FeedbackThank you for your feedback Our editors will review what you’ve submitted and determine whether to revise the article. External Websites
Alternate titles: heterophil, neutrophyllic leukocyte By The Editors of Encyclopaedia Britannica Last Updated: Nov 11, 2022 Article History Table of Contentschronic granulomatous disease See all media Related Topics:granulocyte neutrophilia degranulation neutropenia...(Show more) See all related content → 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. Britannica Quiz Human Body: Fact or Fiction?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. 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. What is the term for cell movement through the lining of blood vessels?Leukocytes are able to move through the capillary walls into the tissue spaces, a process called diapedesis.In the tissue spaces they provide a defense against organisms that cause disease and either promote or inhibit inflammatory responses.
What is the process of diapedesis?92. TEM, or diapedesis, is the process whereby the leukocyte squeezes in ameboid fashion across the endothelial cells. This almost always happens at endothelial cell borders101,117 (a small fraction of transmigration occurs through the endothelial cell body; this will be discussed later).
What is the name of the process by which white blood cells move in and out of blood vessels?Leukocytes pass through spaces between blood vessel cells and the process from attachment to transport across the wall of the blood vessels is called diapedesis. Diapedesis is followed by movement of leukocytes toward the areas of infection marked by high concentration of inflammatory proteins.
What causes diapedesis?Diapedesis is initiated by the chemotactic activation of leukocytes and VECs in response to cytokines (IL-1 and TNF-α) and chemokines (CXC and IL-8) (4–6). Upon activation, leukocytes bind to the selectin molecules on VECs that facilitate rolling on and adhesion to VEC membranes.
|
