TISSUE RESPONSE TO INJURY I. THE INFLAMMATORY RESPONSE: This response can be acute or chronic. Acute inflammation has a short onset and short duration. Chronic has a long onset and long duration. A. Acute inflammation: Three phases: acute, repair, and remodeling 1. Phase I: Acute phase: a. initial body response b. first three to four days. Inflammation is a response triggered by damage to living tissues. The inflammatory response is a defense mechanism that evolved in higher organisms to protect them from infection and injury. Its purpose is to localize and eliminate the injurious agent and to remove damaged tissue components so that the body can begin to heal.
Cells or tissues of the body may be injured or killed by any of the agents physical, chemical, infectious described earlier. When this happens, an inflammatory response or inflammation naturally occurs in the healthy tissues adjacent to the site of injury. Inflam-mation is a defensive reaction intended to neutralize, control, oreliminate the offending agent and to prepare the site for repair. It is a nonspecific response not dependent on a particular cause that is meant to serve a protective function.
For example, inflamma-tion may be observed at the site of a bee sting, in a sore throat, in a surgical incision, and at a burn site. Inflammation also occurs in cell injury events, such as strokes and myocardial infarctions.
Inflammation is not the same as infection. An infectious agent is only one of several agents that may trigger an inflammatory re-sponse. Regardless of the cause, a general sequence of events occurs in the local inflammatory response.
This sequence involves changes in the microcirculation, how to make cute kawaii plushies vasodilation, increased vascu-lar permeability, and leukocytic cellular infiltration Fig.
As these changes take place, five cardinal signs of inflammation are produced: redness, heat, swelling, pain, and loss of function. The transient vasoconstriction that occurs immediately after injury is followed by vasodilation and an increased rate of blood flow through the microcirculation.
Local heat and redness result. Next, vascular permeability increases, and plasma fluids includ-ing proteins and solutes leak into the inflamed tissues, produc-ing swelling. The pain produced is attributed to the pressure of fluids or swelling on nerve endings, and to the irritation of nerve endings by chemical mediators released at the site. Bradykinin is one of the chemical mediators suspected of causing pain.
Loss of function is most likely related to the pain and swelling, but the exact mechanism is not completely known. As blood flow increases and fluid leaks into the surrounding tissues, the formed elements red blood cells, white blood cells, and platelets remain in the blood, causing it to become more vis-cous. Leukocytes white blood cells collect in the vessels, exit, and migrate to the site of injury to engulf offending organisms and to remove cellular debris in a process called phagocytosis.
Fibrinogen in the leaked plasma fluid coagulates, forming fibrin for clot formation, which serves to wall off the injured area and prevent the spread of infection. Injury initiates the inflammatory response, but chemical sub-stances released at the site induce the vascular changes.
Foremost among these chemicals are histamine and the kinins. Histamine is present in many tissues of the body but is concentrated in the mast cells. It is released when injury occurs and is responsible for the early changes in vasodilation and vascular permeability. Kinins increase vasodilation and vascular permeability; they also attract neutrophils to the area.
Prostaglandins, another group of chemical substances, are also suspected of causing increased per-meability. The inflammatory response is often confined to the site, causing only local signs and symptoms. However, systemic responses can also occur. Fever is the most common sign of a systemic response to injury, and it is most likely caused by endogenous pyrogens internal substances that cause fever released from neutrophils and macrophages specialized forms of leukocytes.
These sub-stances reset the hypothalamic thermostat, which controls body temperature, and produce fever. Leukocytosis, an increase in the synthesis and release of neutrophils from bone marrow, may occur to provide the body with greater ability to fight infection. During this process, general, nonspecific symptoms develop, in-cluding malaise, loss of appetite, aching, and weakness. Inflammation is categorized primarily by its duration and the type of exudate produced.
It may be acute, subacute, or chronic. Acute inflammation is characterized by the local vascular and exudative changes described earlier and usually lasts less than 2 weeks. An acute inflammatory response is immediate and serves a protective.
After the injurious agent is removed, the inflammation subsides and healing takes place with the return of normal or near-normal structure and function. Chronic inflammation develops if the injurious what a security guard does persists and the acute response is perpetuated. Symptoms are present for many months or years. Chronic inflammation may also begin in-sidiously and never have an acute phase.
The chronic response does not serve how to clean pc case window beneficial and protective function; on the con-trary, it is debilitating and can produce long-lasting effects. As the inflammation becomes chronic, changes occur at the site of in-jury and the nature of the exudate becomes proliferative.
A cycle of cellular infiltration, necrosis, and fibrosis begins, with repair and breakdown occurring simultaneously. Considerable scarring may occur, resulting in permanent tissue damage. Subacute inflammation falls between acute and chronic in-flammation. It includes elements of the active exudative phase of the acute response as well as elements of repair, as in the chronic phase. The term subacute inflammation is not widely used.
BS Developed by Therithal info, Chennai. Toggle navigation BrainKart. Chemical Mediators Injury initiates the inflammatory response, but chemical sub-stances released at the site induce the vascular changes. Systemic Response to Inflammation The inflammatory response is often confined to the site, causing only local signs and symptoms. Types of Inflammation Inflammation is categorized primarily by its duration and the type of exudate produced.
An acute inflammatory response is immediate and how to cure ear wax blockage a protective function. Related Topics Nursing Implications. Stress at the Cellular Level. Control of the Steady State. Cellular Adaptation.
Cellular Injury. Cellular Response to Injury: Inflammation. Cellular Healing. Nursing Implications - Stress at the Cellular Level. Stress Management: Nursing Interventions. Holistic Approach to Health and Health Care. The Brain and Physical and Emotional Health. Emotional Health and Emotional Distress. Family Health and Distress.
local response of the body to an injury or irritant. 2 Purposes of Inflammation. 1. defend the body against foreign substances (wall off injury/knight) 2. dispose of dead/dying cells and tissue so repair can take place (laborers) 5 Cardinal signs of inflammation. 1. redness. 2. heat. 3. edema. When inflammation happens, chemicals from your body's white blood cells enter your blood or tissues to protect your body from invaders. This raises the blood flow to the area of injury or. When this happens, an inflammatory response (or inflammation) naturally occurs in the healthy tissues adjacent to the site of injury. Inflam-mation is a defensive reaction intended to neutralize, control, oreliminate the offending agent and to prepare the site for repair.
Inflammation , a response triggered by damage to living tissues. The inflammatory response is a defense mechanism that evolved in higher organisms to protect them from infection and injury. Its purpose is to localize and eliminate the injurious agent and to remove damaged tissue components so that the body can begin to heal. The response consists of changes in blood flow, an increase in permeability of blood vessels , and the migration of fluid, proteins , and white blood cells leukocytes from the circulation to the site of tissue damage.
An inflammatory response that lasts only a few days is called acute inflammation, while a response of longer duration is referred to as chronic inflammation. Inflammation is a response triggered by damage to living tissues. The response consists of changes in blood flow, an increase in permeability of blood vessels, and the migration of fluid, proteins, and white blood cells leukocytes from the circulation to the site of tissue damage.
The four cardinal signs of inflammation are redness Latin rubor , heat calor , swelling tumor , and pain dolor. Inflammation serves as a defense mechanism against infection and injury, and localizing and eliminating injurious factors and removing damaged tissue components allows the healing process to begin.
During the healing process, damaged cells capable of proliferation regenerate. Tissue repair, resulting in scar formation, may occur when normal tissue architecture cannot be regenerated successfully. Failure to replicate the original framework of an organ can lead to disease. Acute inflammation is usually beneficial but often causes unpleasant sensations, such as pain or itching.
In some instances inflammation can cause harm. Tissue destruction can occur when the regulatory mechanisms of the inflammatory response are defective or the ability to clear damaged tissue and foreign substances is impaired. In other cases an inappropriate immune response may give rise to a prolonged and damaging inflammatory response. Although acute inflammation is usually beneficial , it often causes unpleasant sensations, such as the pain of a sore throat or the itching of an insect bite.
Discomfort is usually temporary and disappears when the inflammatory response has done its job. But in some instances inflammation can cause harm. The factors that can stimulate inflammation include microorganisms, physical agents, chemicals, inappropriate immunological responses, and tissue death.
Infectious agents such as viruses and bacteria are some of the most common stimuli of inflammation. Viruses give rise to inflammation by entering and destroying cells of the body; bacteria release substances called endotoxins that can initiate inflammation.
Physical trauma, burns , radiation injury , and frostbite can damage tissues and also bring about inflammation, as can corrosive chemicals such as acids, alkalis, and oxidizing agents. As mentioned above, malfunctioning immunological responses can incite an inappropriate and damaging inflammatory response. Inflammation can also result when tissues die from a lack of oxygen or nutrients, a situation that often is caused by loss of blood flow to the area.
The four cardinal signs of inflammation—redness Latin rubor , heat calor , swelling tumor , and pain dolor —were described in the 1st century ad by the Roman medical writer Aulus Cornelius Celsus. Redness is caused by the dilation of small blood vessels in the area of injury. Heat results from increased blood flow through the area and is experienced only in peripheral parts of the body such as the skin. Fever is brought about by chemical mediators of inflammation and contributes to the rise in temperature at the injury.
Swelling, called edema , is caused primarily by the accumulation of fluid outside the blood vessels. The pain associated with inflammation results in part from the distortion of tissues caused by edema, and it also is induced by certain chemical mediators of inflammation, such as bradykinin, serotonin , and the prostaglandins.
A fifth consequence of inflammation is the loss of function of the inflamed area, a feature noted by German pathologist Rudolf Virchow in the 19th century. Loss of function may result from pain that inhibits mobility or from severe swelling that prevents movement in the area. When tissue is first injured, the small blood vessels in the damaged area constrict momentarily, a process called vasoconstriction. Following this transient event, which is believed to be of little importance to the inflammatory response, the blood vessels dilate vasodilation , increasing blood flow into the area.
Vasodilation may last from 15 minutes to several hours. Next, the walls of the blood vessels, which normally allow only water and salts to pass through easily, become more permeable.
Protein-rich fluid, called exudate, is now able to exit into the tissues. Substances in the exudate include clotting factors, which help prevent the spread of infectious agents throughout the body. Other proteins include antibodies that help destroy invading microorganisms. As fluid and other substances leak out of the blood vessels, blood flow becomes more sluggish and white blood cells begin to fall out of the axial stream in the centre of the vessel to flow nearer the vessel wall.
The white blood cells then adhere to the blood vessel wall, the first step in their emigration into the extravascular space of the tissue. Article Introduction Causes Signs The acute inflammatory response Vascular changes Cellular changes Chemical mediators of inflammation Events following acute inflammation Healing and repair Suppuration Chronic inflammation Show more. Videos Images. Additional Info. More About Contributors Article History.
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The main function of complement proteins is to aid in the destruction of pathogens by piercing their outer membranes cell lysis or by making them more attractive to phagocytic cells such as macrophages a process known as opsonization. Some complement components also promote inflammation by stimulating cells to release histamine and by attracting phagocytic cells to the site of infection. Top Questions. How Is Inflammation Involved in Swelling? Read more below: Signs. Get a Britannica Premium subscription and gain access to exclusive content.
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