Inflammation & Tissue Repair Flashcards
(35 cards)
What is inflammation?
Inflammation is the vascularised tissue response to injury.
What is a vascular and avascular tissue? give examples
Vascular tissue have blood supply to it, avascular do not.
Examples of vascular tissues:
- Muscle tissue, tissues of liver and lungs
Examples of avascular
- Cornea and lens of the eye, cartilage etc
Avascular tissues have no direct blood supply, how do they receive nutrients?
Through diffusion
In what type of tissues is inflammation usually not manifested?
Avascular
What is the function of inflammation?
It is a protective response
Serves to bring defense & healing mechanisms to the site of injury.
What are the cardinal signs and cause of acute inflammation?
Rubor (redness) - due to dilatation of small blood vessels
Tumor (swelling) - due to accumulation of fluid
Calor (heat) - due to increased blood flow
Dolor (pain) - due to stretching and distortion of skin due to bradykinin.
What are the benefits of Inflammation?
If inflammation occurs in a small period of time it is beneficial.
1. Dilutes, destroys or neutralizes the offending agents Brings antibodies, complement factors, and immune cells to fight against the infection.
- Inflammation is followed by repair
During this process dead cells are removed so that healing can take place.
What are the harmful effects of inflammation?
If inflammation prolongs (AKA chronic inflammation) both the initially inflammatory reaction & the subsequent healing process can case harm in delicate tissues.
Chronic inflammation is associated with healing process - leads to fibrous tissue deposition, which interferes with the normal functioning of that organ.
Inflammation causes insulin resistance = increase in risk of heart disease
What are the causative agents of inflammation?
- Infection
- Trauma
- Necrosis
- Immune-mediated
- Toxin
- Chemical
Describe the process of inflammation.
- Vasodilation and permeability of blood vessels increase
- Phagocyte migration and phagocytosis
- Tissue repair and healing
What are the types of inflammation?
Acute (short duration - days to few weeks)
Chronic (longer duration - weeks to years)
What is the inflammatory response?
The body’s second line of defense against invasion of pathogens.
Describe the steps of the inflammatory response
- DAMAGE TO TISSUE
bacteria enters cell - when they die liberate FPRs - attracts neutrophils towards site of inflammation - MAST CELLS RELEASR HISTAMINES
present under the skin - when they are damaged liberate histamines
causes vasodilation - pores between endothelium widens causing fluid (contains antibodies and other elements to help kill pathogens) to leak out into tissue. - PHAGOCYTE MIGRATION TO ENGULF + KILL BACTERIA
Phagocytes try engulf bacteria and kill it - Platelets aggregate to seal the capillaries in the wounded area.
Vascular reactions of inflammation
Cellular reactions of inflammation
Neutrophils (1st) and monocytes (2nd) move to inner surface of capillaries (uni directional) and then migrate through capillary wall to site of injury
Chemotaxis - attracts neutrophil to site of inflammation
immune cells to move toward the periphery of the vessel, roll along the vascular wall and adhere to endothelial cells
What is chemotaxis?
Movement of cells towards the site of inflammation in
response to chemotactic substances
What are the mediators of inflammation?
Two types:
1. Plasma derived
2. Cell derived
Mediators of Inflammation - Plasma-derived
- Hageman factor ( AKA clotting factor 12)
a) Important in order to start the cascade of clotting
b) leads to formation of thrombin which breaks down fibrinogen into fibrin
c) fibrin causes vasodilation
Factor 12 also causes the activation of the inactive protein kallikrein - when activated - becomes an active enzyme - like kinins
Then through a series of reactions leads to the production of bradykinin (causes vasodilation and pain)
- Bacteria activates complement system - C3a and C5a act on mast cells to produce histamines = vasodilation
Mediators of Inflammation - Cell-derived
All produce chemicals responsible for vasodilation:
- Mast cells/basophil degranulation - histamines
- Platelets - serotonin
- Inflammatory cells - platelet activation factor, prostaglandins
- Endothelium - produces nitric oxide, platelet activation factor and prostaglandins
Cell derived lipid mediators of inflammation
Is the inflammatory fluid an exudate or transudate and why?
Exudate
Reason: due to increased vascular permeability
rich in protein
many WBC
appearance: turbid
What are examples of acute inflammation?
Pneumonia and acute appendicitis are the examples of acute inflammation of lung and appendix respectively.
In pneumonia, the alveolar sacs get filled with protein rich fluid (exudate) and inflammatory cells initially with neutrophils and later with macrophages.
What are the outcomes of acute inflammation?
- Resolution - restoration to normal with minimal scar formation
- Scaring - fibrosis replaces part of the normal tissue and may cause deformity
- Septicemia - may lead to disseminated intravascular coagulation, shock or death
- Chronic inflammation - persistent inflammation or spread
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
