Learn: Cell Recognition and the Immune System

Welcome!Today we'll explore cell recognition and the immune system. This is an important topic for understanding how your body defends itself against harmful pathogens. Let's dive in and learn step by step!

What is the immune system?The immune system is your body's defence against infections. It recognises and destroys harmful organisms like bacteria, viruses, and fungi. Without it, we couldn't survive exposure to the environment.

Cell RecognitionYour immune system uses cell-surface molecules, such as proteins, to identify whether cells in your body are 'self' or 'non-self'. This helps it distinguish between your own cells and harmful invaders like pathogens. Antigens are molecules found on the surface of pathogens that trigger an immune response.

PhagocytosisOne of the first steps in the immune response is phagocytosis. Specialised cells called phagocytes engulf and digest pathogens. Phagocytes recognise antigens on the pathogen's surface, then trap and destroy them using enzymes found in their lysosomes.

Humoral ResponseThe humoral response involves B lymphocytes. These cells produce antibodies that bind to specific antigens. This leads to the formation of antigen-antibody complexes, which help neutralise the pathogen and mark it for destruction.

VaccinesVaccines introduce harmless forms of antigens into the body. This stimulates an immune response without causing illness, leading to the production of memory cells. These cells enable your immune system to respond more rapidly and effectively if the same pathogen is encountered again.

HIV (Human Immunodeficiency Virus)HIV is a virus that attacks the immune system, specifically T helper cells. It uses its attachment proteins to bind to receptors on T helper cells and injects its genetic material. This weakens the immune system, making it harder for the body to fight infections.

Monoclonal AntibodiesMonoclonal antibodies are artificially produced antibodies that bind to specific antigens. They can be used in medical treatments to target diseases, deliver drugs, or assist in diagnostics. An example is using monoclonal antibodies to detect specific antigens in techniques like ELISA.

Review Time!Great work! You've learned about how the immune system recognises pathogens, the process of phagocytosis, the humoral response, vaccines, HIV, and monoclonal antibodies. Now let's test your knowledge with a few questions.