Lecture 7 General Pathology (2) (7) (2) PDF

Inflammation Definition: Is a local protective response of living tissue against irritant. Function of the inflammatory response: The inflammatory process is designed to inactivate and remove the injurious agent, remove any damaged tissue resulting from the injury, and help repai...

Inflammation Definition: Is a local protective response of living tissue against irritant. Function of the inflammatory response: The inflammatory process is designed to inactivate and remove the injurious agent, remove any damaged tissue resulting from the injury, and help repair and healing. Causes of inflammation Immune Chemical reaction poisons Physical and Infectious thermal agents injuries Nomenclature of inflammation: Inflammation is designated by adding the suffix “itis” to the English, Latin or Greek name of the organ. For examples: Stomatitis-------------Inflammation of oral cavity arthritis----------------Inflammation of joint Tonsilitis---------------Inflammation of tonsil Nephritis--------------Inflammation of kidney. Hepatitis--------------Inflammation of liver.  The 5 Cardinal Signs of Heat Redness Swelling Pain Loss Of Func.  Cardinal signs of inflammation 1. Redness : by increased of blood in the inflammed part (hyperaemia) 2. Swelling : due to accumulation of exudate. 3. Hotness due to: 1. Blood from internal organs (warmer) rushes to the inflamed area. 2. Metabolic rate in the inflamed area is increased 4. Pain: due to 1. Pressure on the nerve endings by exudate. 2. - Liberated chemical mediators. 5. Loss of function due to: 1. -Pain 2. -Edema which may cause a mechanical disability. 3. -Tissue damage  Microscopic picture of inflammation: It includes vascular and exudative changes. Vascular changes in inflammation: 1- changes in the caliber A) Transient constriction b) Long-standing vasodilatation 2- Change in blood flow a- acceleration b- slowing of blood flow 3- Increase in vascular permeability  Inflammatory Exudate Consists of: 1- Fluid exudate. 2- Cellular exudate. Functions of inflammatory fluid exudate: 1-It dilutes toxin, chemicals and poisons, so minimize their effects. 2-Brings antibodies from the blood to the site of inflammation. 3-Supplies nutrition for the cells and carries away waste products. 4-Supplies fibrinogen which changes to fibrin Function of fibrin: -Localizes infection by surrounding the inflamed area. -Forms network upon which inflammatory cells move toward the irritant and upon which fibroblast start to healing process.  2- Cellular exudates 1. Polymorphonuclear Leukocytes (Synonym: granulocytes) a) Neutrophils b) Eosinophils c) Basophils / Mast Cells 2. Mononuclear leukocytes a) Monocytes and Macrophages b) Lymphocytes and plasma cells Microscopic picture of inflammatory exudate showing dark pink fibrin threads and inflammatory cells. H&E Formation of the inflammatory cellular exudate occurs along the following steps: The leukocytes fall out of the 1) Margination central column and go slowly to the periphery of the vascular lumen The leukocytes become adhered to 2) Pavementation: the endothelial cells It is the process by which leukocytes 3)Emigration: escape from the blood to the perivascular tissues, - is the directional migration in response to a chemical gradient 4) Chemotaxis: of chemoattractant  Diagram showing sequence of movement of leukocytes in inflammatory process (margination, adhesion and emigration). Mechanism of Inflammation: Diagrammatic illustration to show the steps of cellular movement and phagocytosis.  Illustration showing sequence of cellular response in acute inflammation including margination, adhesion, emigration and phagocytosis. Phagocytosis represented by engulfing of irritant by macrophages. H&E  1. Polymorphonuclear Leukocytes (Synonym: granulocytes) Morphology Function Neutrophils are the major cellular defense system against bacteria 1-Phagocytosis: 2. Mediate tissue injury: 3. Regulate inflammatory response Eosinophils numerous at inflammatory sites which result from: 1. Parasites 2. Allergic or Immunologic Disease Basophils and mast cells Intimately involved in hypersensitivity reactions. Contains heparin and histamine  2. Mononuclear cells Morphology Function Macrophages 1-Antimicrobial and phagocytic cells. 2- clean up debris 3- antigen presenting cell. B-Lymphocytes 1- Important in production of antibody (humoral immunity). 2-One basis defense against viral disease and toxicosis. 3- antigen presenting cell. T-lymphocytes - Responsible for cell mediated immunity  Chemical mediators include Histamine Serotonin Kinins Plasmin Complement Anaphylotoxins Prostaglandins  Histamine Released from mast cells Dilatation of arteriols Increase permeability of capillaries and venules Has brief action Sustained action comes from other mediators Serotonine Has similar action of histamine Anaphylotoxins Are effector of histamine release  Prostaglandins Stimulate the release of histamine Act very early in the inflammatory process Fever Pain Vasodilatation Increase the permeability Bradykinin Stimulate prostaglandins  Kinins Inactive plasma kallikrene ↓ Active plasma kallikrene ↓ Plasma kininogen → kinins → pain vasodilatation Capillary permeability Smooth muscle dilatation Classification of inflammation: A- According to the degree of tissue reaction 1- Adequate reaction 2- Inadequate reaction 3- Excessive reaction B -According to duration: 1- Per acute inflammation 2- Acute inflammation 3- Subacute inflammation 4- Chronic inflammation.