3) Seroflo Traning Module-Asthma Pathophisiology (3).pptx

Seroflo Medical Training Asthma Pathophysiology Section Objective You need to know from this section • What is inflammation? • What is the asthma pathophysiology. • Inflammation key component • Inflammation key features. • Inflammation types. Pathophysiology of Asthma Inflammation • Inflamma...

Seroflo Medical Training Asthma Pathophysiology Section Objective You need to know from this section • What is inflammation? • What is the asthma pathophysiology. • Inflammation key component • Inflammation key features. • Inflammation types. Pathophysiology of Asthma Inflammation • Inflammation is a natural defense mechanism of body tissue to injury or irritation. • It occurs following activation of the immune system . • In some cases if the body is exposed to an irritant it may become ‘sensitized, causing the body to respond abnormally to harmless stimuli. People who respond in this way are termed atopic (allergic). • Inflammation can be described as chronic or acute. Pathophysiology of Asthma Inflammation • Acute inflammation has a sudden onset i.e. may be the result of an infection or injury, and subsides quickly. Acute inflammation can become chronic if not appropriately treated. • Chronic inflammation develops more slowly and lasts longer. It usually occurs as a result of repeated infection or irritation. Chronic inflammation can irreversibly damage tissue if not treated. • The     characteristic signs of inflammation are: heat Redness Swelling pain/tenderness. Pathophysiology of Asthma Key features of inflammation • Vasodilation: Small blood vessels (capillaries) in the tissue dilate to allow a greater blood supply to the area affected. Within the blood are O2 and white blood cells, which fight infection and clear away damaged cells. • Increased vascular permeability: The walls of the capillaries become more permeable so that more fluid (serum) that carries white blood cells can ‘leak’ through to the affected area. The resultant swelling, caused by the increased fluid, is called oedema. • Infiltration and activation of additional cells: These are cells specifically associated with the inflammatory process. Some of these cells have the ability to attract even more white blood cells to the affected area. This is known as chemotaxis. Pathophysiology of Asthma Key features of inflammation Two broad categories of mediators  Mediators – chemicals released as a result of action within the inflammatory process. Pre-formed mediators • These mediators are already formed and are present in the cell cytoplasm in the form of granules. They are immediately released, through a process called degranulation, when the cell membrane is broken. •Newly Pre-formed mediators include histamine (from mast cells). synthesized mediators • These mediators are formed from arachidonic acid, which is derived from the breakdown of the cell membrane by the enzyme phospholipase A 2. • Newly synthesized mediators include leukotrienes, prostaglandins •Bronchoconstrictors •inhibit the mucociliary clearance •increase blood flow and permeability •edema formation, •attract and activate leukocytes Two broad categories of mediators Phases in the development of inflammation • Inflammation in asthma develops over time. • This development can be divided into three phases. 1 Early phase: This occurs in the st hour following a challenge by a trigger factor. There is rapid bronchoconstriction. Mast cells are stimulated to release their pre-formed mediators, including histamine (preformed mediators), which they have stored in granules (‘degranulation’). The mediators cause the blood vessels to dilate and also to become more permeable. Fluid leaks out of the blood vessels and into the surrounding tissue . 24  Late phase: This phase lasts for about hours. During this phase there is cellular infiltration (including a build-up of neutrophils and eosinophils attracted by the process of chemotaxis). Newly synthesized mediators are released by the breakdown of arachidonic acid. Some of these mediators cause bronchoconstriction. Phases in the development of inflammation Chronic phase This is a chronic inflammatory phase, caused by repeated exposure to trigger factors. Characteristics of this phase are a recruitment of eosinophils, excess mucus production, thickening of the basement membrane and shedding of the surface epithelium. Thank You