Question

When the human body is invaded by foreign microorganisms such as bacteria and viruses, it produces an immune response. Choose one example of a bacterium or virus to discuss.

• What actions does the body produce in its immune response to invasion by the particular bacterium or virus you selected? Explain your answer.
• Would active or passive immunity be more effective against this bacterium or virus? Why?

Answer 1

                When a pathogen enters our body,first reaction that takes place is inflammation where pathogen tries to enter into the host cells.Inflammation is because of chemicals released by granulocytes such as basophils,neutrophils,mast cells etc.This leads to arrival of B cells,dendritic cells,macrohages to area of infection from nearby lymphoid organs,nodes.

               B cells,dendritic cells,macrohages are called Antigen presenting cells(APCs).APCs activates T cells.Activated T cell produces Th cell and Tc cell.Th cell proliferates B cell into Plasma cell and memory cell(Humoral immunity).Plasma cells produces anti bodies specific to pathogen.Tc cells kills infected cells by finding cells which exposes antigens on MHC-1 receptor(cell mediated immunity).

Natural killer cells gets activated incase of viral infection ,that removes infected cells and protects uninfected cells from getting being infected by secreting some signalling molecules.

Complement system will also gets activated.

Upon entry into our body,temperature of our body is raised,to stop microbial growth.This condition is called fever.

Upon entry of pathgens some signalling pathways gets activated.PAMP's-(pathogen associated molecular pattern) molecules activates different signalling pathways.

Passive immunity is more effective ,because antibodies are preformed for a given pathogen.

Passive immunity takes less time to destroy pathogen. Active immunity needs more time to synthesise proper antibodies that fits and destroys antigen(pathogen).