Cell recognition and the immune system


The different molecules on cells in the immune system and their function 


Humoral response


Active immunity

Passive immunity


Monoclonal antibodies


The different molecules on cells in the immune system and their function


Different cells have different molecules presented on their surface to the immune system. These are often protein-based and enable the identification of:


cells from other organisms of the same species
abnormal body cells


The specific immune response is split into humoral immunity and cell-mediated immunity. Humoral is to do with the blood and antibodies. Distinguishing between an antigen and an antibody is very important.


  • Antigen = protein or carbohydrate foreign (not normally present) to a host’s organism
  • Antibody = protein made as a response to detecting an antigen which binds to the antigen and prevents the pathogen from harming the host.


Immunity against invading pathogens is a crucial part of maintaining health. The body has adaptations which prevent invasion by pathogens, as well as processes in place to deal with those that manage to penetrate the body’s primary defenses. The skin and mucous membranes (e.g. mouth) are examples of such defenses. Sweat contains lysozyme which is an enzyme that breaks down bacterial walls.


If pathogens do invade the body, the subsequent immune response is split between:


  1.  Non-specific
  2.  Specific

The non-specific immune response is inflammation and phagocytosis.




White cells (the most common ones are neutrophils) engulf any foreign particles such as dust or bacteria, then digest them and dispose off of the remains. It’s badass, trust me. I’ve got proof:


The enzymes used to break invaders down are lysosomes which fuse with the vesicle which contains the bacteria. All this action happens within the white cell. At the end, the undigested leftovers are disposed off of by exocytosis (kind of like a burp)……

Test Call to Action!