Special Sub-Topic: Inflammation
|Inflammation is a complex reaction of vascularised tissue to an injurious stimulus. |
t. The aim of the inflammatory process is to destroy, dilute or wall off the injurious agent, and sometimes, begin the repair process.
|Which of these processes can cause inflammation?|
All of them (Physical agents, Chemical agents, Biological agents). Physical agents include trauma, radiation and extremes of temperature such as heat which causes burns or the cold which causes frostbite.
Chemical agents are acids, alkalis and poisons.
Biological agents are organisms such as bacteria, fungi, viruses and parasites.
Other process which can cause inflammation are hypoxia (lack of oxygen to tissues) and immunologic reactions such as anaphylactic shock.
|Which of these is not a clinical feature of inflammation? |
necrosis. Necrosis is a pathological consequence of cell injury, which can cause inflammation, but it is not a clinical feature as it is not present in every case.
The five clinical features of inflammation are: redness/rubor* (due to increased blood flow to the area), swelling/tumor*, pain/dolor*, heat/calor* (produced by increased metabolic activity) and compromised/loss of function in the tissue.
*original "cardinal signs" of inflammation
|What is the name for the protein-rich extravascular fluid produced in inflammation? |
exudate. Transudate is an ultrafiltrate of blood which is low in protein and leaves blood vessels due to osmotic pressure in capillaries.
Pus and blood can be present in inflamed areas, but they are not produced during the process.
|There is more than one type of inflammation. |
t. The four types of inflammation are:
Serous - characterised by a watery exudate e.g. bullous pemphigoid, where the skin separates from the underlying infection.
Fibrinous - characterised by the presence of fibrin e.g. fibrinous pericarditis.
Purulent - characterised by pus (made up of dead or dying neutrophils).
Suppurative - discontinuity of the body surface e.g. ulcers.
|Which of these processes is not one of the cellular events involved in the inflammatory process? |
Selection. The cellular events involved in inflammation are:
1) Margination - when white blood cells (leukocytes) fall out of the central axial column within the blood vessel and assume a peripheral position along the endothelium tissue.
2) Rolling - which occurs due to loose adhesion between selectin molecules and carbohydrate ligands on the leukocyte surface.
3) Adhesion - LFA-1 molecules on leukocytes develop affinity for ICAM-1 present on the endothelial surface causing the leukocytes to bind with considerable stability.
4) Diapedesis - leukocytes secrete collagenase which degrades the basement membrane causing the cells to transmigrate across the endothelium.
5) Chemotaxis - locomotion orientated along a chemical gradient.
6) Phagocytosis - leukocytes ingest solid particles by exocytosis and then digest them using lysosomes.
|The following few questions are about the chemical mediators of inflammation:
What is the main effect of histamine? |
dilation of arterioles. Histamine is widely distributed, being present in mast cells, basophils and platelets. It is released in response to physical injury or during an immune reaction, especially allergic reactions. Histamine also causes an increase in the vascular permeability of venules.
Serotonin has similar effects.
|What mediator activates the kinin system? |
bradykinin. The release of bradykinin activates the kinin system which results in increased vascular permeability, smooth muscle contraction, vasodilation of arterioles and pain.
|Cytokines are produced by lymphocytes and platelets. |
f. Cytokines are an 'umbrella term' for chemical mediators produced by lymphocytes and macrophages that modulate the function of other cell types.
Examples are monokines, which are produced by mononuclear phagocytes and lymphokines, which are produced by lymphocytes.
|Which chemical mediator causes vasoconstriction, bronchoconstriction, leukocyte adhesion, chemotaxis, degranulation and oxidative burst? |
Platelet-Activating Factor (PAF). PAF is present in many sources including platelets (naturally), basophils, mast cells, neutrophils, monocytes, macrophages and endothelium.
Nitrous oxide is produced by endothelial cells, macrophages and specific neurons in the brain and directly affects the paracrine system. Effects include vasodilation, reduction in platelet aggregation and adhesion, reduction in leukocyte migration and it is involved in the pathogenesis of shock.
Prostaglandins cause vasodilation and are the main chemical causes of fever and pain (in conjunction with bradykinin).
Complement opsonises (coats) microbes making them more susceptible to phagocytosis, whilst attracting neutrophils to the location via chemotaxis. C3b and C5a bring about the lysis of microbes by the Membrane Attack Complex (MAC).
|Which of the following processes is not a step in phagocytosis? |
Adhesion. Phagocytosis is the process whereby cells ingest solid particles in an attempt to kill/remove the injurious agent.
1) Recognition and attachment - microorganisms are identified when coated by complement
2) Engulfment - the phagocyte binds to the opsonised particle and encloses it completely within a phagosome created by the cell's own cytoplasmic membrane.
3) Killing / degradation - the phagosome within the phagocyte fuses with a lysosome which then 'digests' the particle.
|Which of the following is not a true inflammatory disease? |
scalpitis. All inflammatory conditions have the suffix '-itis' preceded by the affected organ.
Meningitis is inflammation of the meninges surrounding the brain.
Appendicitis is inflammation of the appendix.
Dermatitis is inflammation of the skin.
|What is the common name for inflammation of the joints?|
arthritis. Arthritis is the leading cause of disability in adults over the age of 55, but there is more than just one type.
The most common type is osteoarthritis, a degenerative disease of the joints, which results from physical trauma, infection or age.
Rheumatoid arthritis and psoriatic arthritis are autoimmune diseases where the body's own immune system attacks the joints causing chronic inflammation.
Gouty arthritis is caused by the deposition of uric acid crystals in the joint, resulting in arthritis.
|What is the name given to inflammation of prolonged duration characterised by infiltration of mononuclear cells, tissue destruction and repair involving angiogenesis and fibroblastic proliferation? |
chronic & chronic inflammation. Chronic inflammation can be caused by persistant infection by certain microorganisms (e.g. mycobacterium tuberculosis) or prolonged exposure to potentially toxic agents or an autoimmune disease e.g. rheumatoid arthritis.
|Which of the following is NOT an outcome of chronic inflammation? |
complete absolution (recovery). Outcomes for ACUTE inflammation are:
- complete absolution
- abscess formation
- healing by fibrosis
- chronic inflammation
Outcomes for CHRONIC inflammation are:
- progressive destruction of the affected organ
- dissemination to other organs
- healing by fibrosis
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