"The initial response to acute inflammation includes a rapid drop in numbers of circulating eosinophils, a rapid accumulation of eosinophils at the periphery of the inflammation site and an inhibition of egress of eosinophils from the bone marrow" (Bass, 1976, p.870).
Basophils- Basophils are one of the least common granulocytes and they make their appearance during certain inflammation, especially those that deal will allergies. They have two main functions during inflammation. The heparin substance found in basophils reduces blood clotting while vasodilator histamine in basophils increases blood flow to the tissues and organs.
Neutrophils -- Neutrophils are the most common white blood cells found in the human body and they are present in large numbers at the site of an inflammation. It produces destructive oxidizing agents that can convert dioxygen into hydrogen peroxide and in the process, they kill the bacteria or fungi that is causing the inflammation. They are a kind of phagocytes and have the ability to ingest any other cells. In the process of ingestion, they die and this makes their life a short-lived one. They have a life-span of four to ten hours when it is not in use and dies immediately after ingesting another cell. However, they are constantly produced and this makes the most abundant member of the human immune system. Besides ingesting bacteria, they also release a string of fibers called the neutrophil extracellular trap and this helps to trap the microbes or other particles present around the cell. This ensures that the entire region around the cell is cleaned by one neutrophil.
Monocyte -- Monocyte is a white blood cell that works to produce more macrophages and dendritic cells in human beings. During inflammation, they rush to the site and multiply into macrophages and dendritic cells that can fight the inflammation.
Lymphocyte -- Lymphocytes are a kind of white blood cells that play an active role in fighting inflammation along with the macrophages produced by monocytes. It produces limited amounts of secreted molecules such as interferon and they are also involved in cell to cell interactions. (Ross, 1994). There are three major kinds of lymphocytes and they are T cells, B cells and natural killer cells. The natural killer cells play a role in protecting the body from tumors by identifying these cells and releasing the cytotoxic granules that kill the affected cells. The Thymus (T cells) and Bone (B cells) identify the foreign particles and create a response that is specifically aimed to destroy these substances.
Erythrocytes -- Erythrocytes are the red blood cells in humans and they play a vital role in providing oxygen to the tissues. So, they provide the necessary oxygen at the site of inflammation to help the other cells to recover.
Question 4: Inflammation is the response of vascular tissues to harmful stimuli and also the protective attempt to remove them. Please describe the causes and course of inflammation.
Inflammation is the biological process by which the body's white blood cells fight against infections and foreign substances such as bacteria and fungi. It is a protective response to external stimuli and when it occurs, the white blood cells rush to the site to fight the harmful stimuli. An inflammatory process begins when the tissue is damaged or malfunctioning due a variety of reasons other than injury, infection and foreign substances. This response is triggered by the body when it senses any malfunctioning or imbalance in homeostasis. Though these are of lower magnitude than an injury or infection, the body responds to it. In the case of tissue malfunctioning, the local WBCs present in the tissue fight the inflammation while larger problems such as injury require a more extensive response as mentioned below. (Medzhitov, 2008).
During the inflammatory process, the tissue is damaged and this causes the blood vessels to constrict lightly in a process called vascoconstriction. Within a few minutes, the blood vessels release and this helps a larger amount of blood to flow into this area. Also, the walls of the blood vessel become permeable to allow a liquid called exudate to ooze through it. This protein-based liquid contains a clotting substance that helps to clot the blood.
While this vascular process is happening, the white blood cells accumulate near the area of injury. They come from different parts of the body as a response to the inflammation. These cells are phagocytes and they have the ability to ingest or digest bacteria and other foreign particles to relieve the place of any unwanted substances. (Encyclopedia Britannica, 2011). One of the most abundant and powerful white blood cells are the neutrophils. They attack the area immediately and more are produced from the bone marrow to combat the foreign particles. They kill the foreign substances by releasing toxic content from their granules and this can cause a certain degree of collateral damage to the host. This results in necrosis where the cells and the underlying tissues are killed from the substances released by the WBCs. If the inflammation still persists, then the neutrophils are replaced by macrophages and also T cells in the case of infections. These work together to kill the foreign substance.
In the case of virus, nuclear materials and other non-biological substances, the T cells and B cells of the lymphocyte springs into action. Both these cells generate a specific response that is tailored to destroy these substances. T-cells cause cell mediated injury in which no antibodies are released. These T cells bind to the other cells that have antigen and will trigger a response that can include lymphocytes or leukocytes. The B cells, on the other hand, trigger a form of protection called the humoral immunity in which the B cells transform themselves into plasma cells that secrete antibodies to fight the foreign substance.
Chronic inflammation occurs when the WBCs are unable to kill the foreign substance because they are un-degradable or there is extensive tissue damage due to autoimmune responses. These unsuccessful attempts lead to the formation of granulomas or walled substances that prevent the foreign object from entering the bloodstream as a final way to protect the host.
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