ICS - Pathology 2 Flashcards
Define inflammation
A local physiological response to tissue injury
Give an advantage of inflammation
Can destroy invading micro-organisms and can prevent the spread of infection
Give a disadvantage of inflammation
Can produce disease and lead to distorted tissues with permanently altered function
Define acute inflammation
Initial and often transient series of tissue reactions to injury
What are the main cells involved in acute inflammation?
Neutrophils and monocytes
What are the main steps of acute inflammation?
- Initial reaction of tissue to injury- Vascular component (vessels dilate)- Exudative component (vascular leakage of protein-rich fluid)- Neutrophil polymorph (phagocytose)
Define exudate
A protein-rich fluid that leaks out of vessel walls due to increased vascular permeability
What are examples of acute inflammation?
- Acute appendicitis- Frostbite - Streptococcal sore throat
What vascular changes occur in acute inflammation?
- Increased blood flow through capillaries- Increased vascular permeability (exudation)
What is the role of tissue macrophages in acute inflammation?
Secrete chemical mediators that attract neutrophil polymorphs
What is the role of the lymphatic system in acute inflammation?
Lymphatic channels dilate and drain away oedematous fluid (reduces swelling). Antigens are also carried to lymph nodes for recognition by lymphocytes
What are the main steps of neutrophil polymorph migration?
- Margination 2. Adhesion/Pavementing3. Emigration4. Diapedesis
Describe margination (neutrophil polymorph migration)
Neutrophils migrate to the peripheral part of blood vessels near the endothelium due to increased plasma viscosity
Describe adhesion/pavementing (neutrophil polymorph migration)
Neutrophils adhere to vascular endothelium in venules. Results from interactions between paired adhesion molecules (on leucocyte and endothelial surfaces)
Describe emigration (neutrophil polymorph migration)
Neutrophils pass through endothelial cells and through the basal lamina into the adventitia
Describe diapedesis (neutrophil polymorph migration)
A passive process that depends on hydrostatic pressure. RBCs sometimes escape from vessels which indicates severe vascular injury (e.g. tear in vessel wall)
What is released from injured tissues that causes the acute inflammation response to spread?
Chemical mediators e.g. histamine and thrombin
Give 3 endogenous chemical mediators of acute inflammation
- Bradykinin2. Histamine3. Nitric oxide
What is the main source (and other sources) of histamine?
Mast cells (stored in granules in their cytoplasm)Also basophils, eosinophils and platelets
What do chemical mediators such as histamine cause?
- Vasodilation- Emigration of neutrophils- Chemotaxis- Increased vascular permeability- Itching and pain
Give 6 causes of inflammation
- Microbial infections (bacteria, viruses)2. Hypersensitivity reactions (parasites, TB)3. Physical agents (trauma, burns, frost bite)4. Chemicals (corrosives, acids, alkalis)5. Bacteria toxins6. Tissue necrosis (ischaemia, infarction)
What does viral infection result in?
Cell death due to intracellular multiplication
What does bacterial infection result in?
The release of exotoxins (involved in the initiation of inflammation) or endotoxins
What are the 5 cardinal signs of inflammation?
- Rubor (redness)2. Calor (heat)3. Tumor (swelling)4. Dolor (pain)5. Loss of function