Quiz 35: Immunity


Susceptibility is a condition in which a person is vulnerable to being infected by a certain disease while resistance indicates the capacity of an organism to defend itself against harmful microbes. Innate Immunity is an inborn non specific capacity in a person for resisting disease while acquired immunity is the acquired resistance of the individual against a particular microbe or disease. These traditionally recognized types of immunity are more difficult to distinguish now as the study of innate immunity in invertebrates has begun to blur between the lines between acquired and innate immunity systems. The phenomena of memory and specifity of responses have now been found in invertebrates also. Invertebrate animals apparently also possess a specific immunological memory. Invertebrates can increase their defense mechanism's activity following contact with pathogens or parasites.

The innate defense mechanisms that are chemical in nature are: • The enzyme lysozyme can be found in most of the secretions including tears. • The low pH in the stomach makes it a less desirable place for colonization by other organisms. • The vagina also has a low pH to prevent any microbial growth. The vaginal secretions prevent any growth by microbes. • Mucus is produced by mucous membranes that line the digestive and respiratory tracts The complement is a group of serum proteins that are activated in a particular sequence as a part of the host immune response against microbes.

After a phagocyte has engulfed a particle, the events which follow are: • The engulfed particle becomes enclosed within an intracellular vacuole. • Lysosomes then merge with this vacuole. • They then secrete digestive enzymes into the vacuole. • They produce toxic intermediates like img which digest the particle.

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