why the third line of defence takes more time to respond to an infection than the second line of defence.

For the third line of defense is the line that is responsible for the formation of antibodies and acquired immunity that affects the immunological memory.

Explanation:

Antibodies or immunological memory is formed thanks to antigen-presenting cells that engulf the antigen or pathogen, exposing its characteristic molecule on the surface, so that the lymphocyte lineage can reproduce an antibody in relation to that specific molecule, forming as produces a specialized antibody to a particular antigen for subsequent contact with it.

Immunology has three barriers or three lines, the first is the rapid response, cell filtration, pyocytes and neutrophil nuclear polymorphs that seek to destroy the antigen, these when undergoing cell death make up a collection of pyocytes that are known as purulent collection.

The second line is phagocytosis by APCs or antigen presenting cells, rich in the release of chemical mediators, multinucleated, with large lysosomal systems that digest the antigen.

And the last line, is the lymphocyte, where it is sought to form a specific antibody, it seeks a lymphocytic recruitment already matured in the nodes, that is why it takes longer, because it takes more energy and time for our immune system, in addition They depend on the compliance and proper functioning of the first two lines of defense.