MCQ Pathology Answer 6

Beneficial effects

Both the fluid and cellular exudates may have useful effects. Beneficial effects of the fluid exudate are as follows:

Dilution of toxins. Dilution of toxins, such as those produced by bacteria, allows them to be carried away in lymphatics.

Entry of antibodies. Increased vascular permeability allows antibodies to enter the extravascular space, where they may lead either to Iysis of microorganisms, through the participation of complement, or to their phagocytosis by opsonisation. Antibodies are also important in neutralisation of toxins.

Drug transport. The fluid carries with it therapeutic drugs such as antibiotics to the site where bacteria are multiplying.

Fibrin formation. Fibrin formation from exuded fibrinogen may impede the movement of micro-organisms, trapping them and so facilitating phagocytosis.

Delivery of nutrients and oxygen. Delivery of nutrients and oxygen, essential for cells such as neutrophils which have high metabolic activity, is aided by increased fluid flow through the area.

Stimulation of immune response. The drainage of this fluid exudate into the lymphatics allows particulate and soluble antigens to reach the local Iymph nodes where they may stimulate the immune response.

Harmful effects

The release of Iysosomal enzymes by inflammatory cells may also have harmful effects:

Digestion of normal tissues. Enzymes such as collagenases and proteases may digest normal tissues, resulting in their destruction. This may result particularly in vascular damage, for example in type III hypersensitivity reactions and in some types of glomerulonephritis.

Swelling. The swelling of acutely inflamed tissues may be harmful: for example, the swelling of the epiglottis in acute epiglottitis in children due to Haemophilus influenzae infection may obstruct the airway, resulting in death. Inflammatory swelling is especially serious when it occurs in an enclosed space such as the cranial cavity. Thus, acute meningitis or a cerebral abscess may raise intracranial pressure to the point where blood flow into the brain is impaired, resulting is ischaemic damage, or may force the cerebral hemispheres against the tentorial orifice and the cerebellum into the foramen magnum (pressure coning).

Inappropriate inflammatory response. Sometimes, acute inflammatory responses appear inappropriate, such as those which occur in type I hypersensitivity reactions (e.g. hay fever) where the provoking environmental antigen (e.g. pollen) otherwise poses no threat to the individual. Such allergic inflammatory responses may be life-threatening, for example extrinsic asthma.

Category: Pathology MCQs