Second Line of Defence PDF

Second Line of defense: An infection occurs when the pathogen makes it past the first line of defence When this happens, the immune system generates a response to fight pathogens in a general way For example, the immune system can trigger a fever, which makes it too hot for the pathogen to surviv...

Second Line of defense: An infection occurs when the pathogen makes it past the first line of defence When this happens, the immune system generates a response to fight pathogens in a general way For example, the immune system can trigger a fever, which makes it too hot for the pathogen to survive General responses to infections are the second line of defense Fever: An increase in body temperature above 38 degrees Makes it too hot for pathogens to survive Inflammation is painful redness and swelling around the site of an infection Phagocytes - white blood cells that destroy anything that they don't recognise in the body When dead white blood cells build up at the site of the wound, they form pus The Third Line of Defense Targets specific pathogen Compromised of mainly white blood cells They identify and destroy pathogens and help develop immunity to those pathogens A few days after the sickness, B cells will travel into the blood stream and look for pathogens B cells produce antibodies Antibodies bind to pathogens to identify them Each pathogen has unique markers, meaning that only specific antibodies can bind onto The B cell releases millions of antibodies onto the blood to combat the infection It clones it self to neutralise the threat Once the infection is defeated, the antibodies remain in the body and this creates immunity After the recovery, the immune system reduces antibody production, and due to their short lifespan the antibody levels will decline T cells are responsible for cell-mediated immunity. They directly attack infected or abnormal cells