Inflammation Flashcards
What are the cardinal signs of acute inflammation?
Rubor (redness): due to dilation of small blood vessels.
Tumor (swelling): due to accumulation of fluid
Calor (heat): due to increased blood flow
Dolor (pain): due to the stretching and distortion of tissues and due to bradykinin.
Loss of function.
What is inflammation?
Response of a vascularised tissue to injury.
It is a protective response.
Serves to bring defence & healing mechanisms to the site of injury.
What is the beneficial aspect of inflammation?
It dilutes, destroys or neutralises the offending agents thus preventing spread of infection.
Inflammation is followed by repair.
What is the harmful aspect?
Both the initial inflammatory reaction and the subsequent healing process can potentially cause harm in delicate tissues such as in the brain.
What are the causes of inflammation?
Infection, trauma, necrosis, immune, toxin and chemical.
What is the process of inflammation?
1) . Vasodilation and permeability of blood vessels increased.
2) . Phagocyte migration and phagocytosis
3) . Tissue healing and repair
What are the steps of the inflammatory response?
1) . Damaged tissues release histamines, increasing blood flow to the area.
2) . Histamine release causes capillaries to leak fluid (exudate).
3) . Phagocyte engulf bacteria & cellular debris
4) . Platelets move out of capillary to seal the wound area.
What does acute inflammation involve?
1) . Alteration of vascular caliber: brief vasoconstriction followed by vasodilation leads to increased blood flow and blood pooling creating redness and warmth.
2) . Change of vascular permeability: increased permeability for plasma proteins and cells create swelling (tumour). Fluid loss leads to concentration of red blood cells and slow blood flow (stasis).
3) . Emigration of leukocytes from microcirculation to offending target.
Vascular changes and fluid leakage during acute inflammation leads to what?
Oedema (characterised by excess watery fluid collecting in the cavities or tissues of the body).
Compare transudate and exudate.
Transudate
Result of increase hydrostatic pressure
Osmotic imbalance due to decrease serum albumin (this is due to protein loss as in case of nephrotic syndrome)
Low protein content
Exudate
Result of inflammation
Vascular permeability
High protein content
What are the causes of increased vascular permeability?
Bradykinin Histamine Serotonin Prostaglandins Nitric oxide Platelet-activating factor
Name some chemical mediators of inflammation and their role.
Histamine and serotonin: increase vascular permeability (vascular leakage), causes muscle contraction
Prostaglandins: promote vasodilation, oedema development, mediate fever and pain.
Cytokines: IL8, aides chemotaxis, TNF, causes tissue damage.
Leukotreins: LTC4, LTD4, LTE4, increases vascular permeability.
PAF: activates and aggregates platelets with the release of serotonin, histamine.
Bradykinin: vascular dilation and increase permeability and pain.
Pyrogens: biological substances that induce fever.
What are the harmful effects of inflammation?
Extra cellular leakage of lysosomal enzymes
Free radicals
Tissue damage
What is chronic inflammation?
An inflammatory response of prolonged duration (weeks-months-years)
Provoked by the persistence of the causative stimulus
Simultaneous presence of inflammation, tissue destruction and repair.
May or may not be associated with granuloma
Infiltration by macrophages, lymphocytes and plasma cells.
What are the causes of chronic inflammation?
Infectious organisms that resist clearance and form a persistent infection in tissue or undrained abscess cavities e.g TB.
Auto-immune diseases
Exposure to irritant non-living foreign material that has not been removed.
Acute vs. chronic inflammation.
Acute Short duration Cells; neutrophils Vascular damage More exudation Little or no fibrosis
Chronic Longer duration Lymphocytes, macrophages, plasma cells Neo-vascularisation Less exudation Prominent fibrosis
What are the laboratory indicators of inflammation?
ESR (erythrocyte sedimentation rate)
C-reactive protein
Leukocytosis.
Granulocytosis with “left shift” of neutrophil population is a good indicator for a severe bacterial infection. True or False?
True.
Describe the process for healing & repair.
1) . Removal of dead and foreign material.
2) . Regeneration of injured tissue from cells of the same type.
3) . Replacement of damaged tissue by new connective tissue.
What does healing depend on?
The regeneration capacity of cells for example labile cells etc.
What happens if there is damage to permanent cell type or any severe damage to connective tissue matrix?
Damaged tissue heals by the formation of granulation tissue which includes new blood vessels formation and secretion of collagen fibres and matrix by fibroblasts. This process leads to the formulation of fibrous scar.
What are the factors affecting healing?
Systemic
Nutrition
Vitamin deficiency
Age
Immune status
Local
Necrosis Infection Blood supply Mobility Foreign body
What are the cellular mediators?
Polymorphonuclear leukocytes or granulocytes (which include neutrophils, eosinophils and basophils), lymphocytes, plasma cells and macrophages.
What is phagocytosis?
The ingestion of debris and bacteria by neutrophils and macrophages.
What are the steps of phagocytosis?
1) the material has to be recognised as foreign or dead.
2) has to be engulfed and ingested
3) finally, it has to be killed or degraded.
What are the factors that coat bacteria to allow them to be readily ingested?
Opsonins.
What are the two major types of opsonins?
Immunoglobulin (IgG)
C3b component of complement.
Describe the process of phagocytosis.
Opsonins bind to the receptors initiating an extension of cell cytoplasm that encircles the particle so that it becomes wrapped in what was originally cell surface membrane. This is called the phagosome. A lysosome filled with destructive enzymes attaches to the phagosome. The enzymes then engulf the foreign particle. If some enzymes leak out of the phagolysosome they can potentially damage adjacent tissue, this is important for attacking large organisms such as worms which cannot be contained in the phagolysosome.
Where can macrophages be derived from?
Stem cells in bone marrow.
List a positive and negative aspect of macrophages in the inflammatory response.
They synthesise and secrete factors that promote tissue formation and enhance healing and repair for example macrophage-derived growth factor stimulates endothelial cells, resulting in new vessel formation.
Macrophages in chronic inflammation produce substances that maintain the inflammatory response which contributes to local tissue damage.
How are scars brought about?
By destruction of the tissue scaffold.
Define healing by primary intention.
Describes a wound closed by approximation of wound margins or by placement of a graft or flap, or wounds created and closed in the operating room.
Define healing by secondary intention.
Describes a wound left open and allowed to close by epithelialisation and contraction.
Define adaptive immunity.
Protection that is mediated by B and T lymphocytes following exposure to specific antigen, and characterised by immunological memory.
Define innate immunity.
Occurs naturally as a result of a persons genetic constitution or physiology and does not arise from a previous infection or vaccination.
