How do different defences work together?

The immune system uses several kinds of defence. Barriers help keep microbes out, broad responses can react after entry, and specific responses recognize particular features. Some responses leave memory for a later matching encounter. That memory is not a defence against every different microbe. Immune defence is a coordinated network rather than a single shield. Innate mechanisms respond broadly, while adaptive cells recognise particular molecular features and may form memory populations. Responses occur together and influence each other. A memory associated with one feature may not match a different feature, so specificity matters when comparing encounters.