Acute and Chronic inflammation from Robins Basic pathology

Introductory slides from Robbins General Pathology for BS MLT students on acute and chronic inflammation.

1. Lecture 2 General Pathology University of Sialkot Dept . Medical lab Tech Topic : Acute and Chronic Inflammation Prepared by : Taimoor Haider

2. Acute and Chronic Inflammation Inflammation; is a response of vascularized tissues to infections and tissue damage that brings cells and molecules of host defense from the circulation to the sites where they are needed, to eliminate the offending agents.

3. Inflammation Although in common medical and lay parlance, inflammation suggests a harmful reaction, it is actually a protective response that is essential for survival. The mediators of defense include phagocytic leukocytes , antibodies, and complement proteins. The process of inflammation delivers leukocytes and proteins to foreign invaders, such as microbes, and to damaged or necrotic tissues. it activates the recruited cells and molecules, which then function to eliminate the harmful or unwanted substances.

4. Inflammation Without inflammation, infections would go unchecked, wounds would never heal , and injured tissues might remain permanent festering sores .

5. The typical inflammatory reaction develops through a series of sequential steps : The offending agent, which is located in extravascular tissues , is recognized by host cells and molecules . Leukocytes and plasma proteins are recruited from the circulation to the site where the offending agent is located. The leukocytes and proteins are activated and work together to destroy and eliminate the offending substance . The reaction is controlled and terminated . The damaged tissue is repaired.

6. Types of Inflammation Inflammation may be of two types , Acute and Chronic Acute The initial, rapid response to infections and tissue damage is called acute inflammation. It typically develops within minutes or hours and is of short duration, lasting for several hours or a few days . Its main characteristics are the exudation of fluid and plasma proteins (edema ) and the emigration of leukocytes, predominantly neutrophils (also called polymorphonuclear leukocytes).

7. Principal mechanisms of increased vascular permeability in inflammation and their features and underlying causes.

8. ACUTE INFLAMMATION When acute inflammation achieves its desired goal of eliminating the offenders, the reaction subsides and residual injury is repaired. Acute inflammation has three major components : D ilation of small vessels, leading to an increase in blood flow, Increased permeability of the microvasculature, enabling plasma proteins and leukocytes to leave the Circulation. E migration of the leukocytes from the microcirculation , their accumulation in the focus of injury , and their activation to eliminate the offending agent

9. Acute Inflamation

10. Chronic Inflammation if the initial response fails to clear the stimulus, the reaction progresses to protracted type of inflammation that is called chronic inflammation . It is of longer duration and is associated with more tissue destruction, the presence of lymphocytes and macrophages, the proliferation of blood vessels, and fibrosis . Chronic inflammation is a prolonged host response to persistent stimuli that may follow unresolved acute inflammation or be chronic from the outset.

11. Chronic Inflammation It is caused by microbes that resist elimination, immune responses against self and environmental antigens, and some toxic substances (e.g., silica); underlies many medically important diseases. It is characterized by coexisting inflammation, tissue injury, attempted repair by scarring, and immune response . These organisms often evoke an immune reaction called delayed-type hypersensitivity

12. Chronic Inflammation • The cellular infiltrate consists of macrophages, lymphocytes, plasma cells, and other leukocytes . It is mediated by cytokines produced by macrophages and lymphocytes (notably T lymphocytes); bidirectional interactions between these cells tend to amplify and prolong the inflammatory reaction . Granulomatous inflammation is a morphologically specific pattern of chronic inflammation induced by T cell and macrophage activation in response to an agent that is resistant to eradication .

13. Features of Acute and Chronic Inflammation

14. CAUSES OF INFLAMMATION Inflammatory reactions may be triggered by a variety of stimuli: Infections (bacterial, viral, fungal, parasitic) and microbial toxins are among the most common and medically important causes of inflammation . Different infectious pathogens elicit distinct inflammatory responses, from mild acute inflammation that causes little or no lasting damage and successfully eradicates the infection, to severe systemic reactions that can be fatal, to prolonged chronic reactions that cause extensive tissue injury.

15. CAUSES OF INFLAMMATION Tissue necrosis elicits inflammation regardless of the cause of cell death, which may include ischemia ( reduced blood flow, the cause of myocardial infarction ). Foreign bodies (splinters, dirt, sutures) may elicit inflammation by themselves or because they cause traumatic tissue injury or carry microbes . Immune reactions (also called hypersensitivity) are reactions in which the normally protective immune system damages the individual’s own tissues.

16. Principal Mediators of Inflammation

17. Principal Mediators of Inflammation

18. Cytokines in Inflammation

19. Cytokines Cytokines are proteins secreted by many cell types ( principally activated lymphocytes, macrophages, and dendritic cells , but also endothelial, epithelial, and connective tissue cells) . That mediate and regulate immune and inflammatory reactions.

20. Chemokines Chemokines are a family of small (8–10 kD ) proteins that act primarily as chemoattractants for specific types of leukocytes . About 40 different chemokines and 20 different receptors for chemokines have been identified.

21. summary