400
List as much as you can about the battle of the 1st line of the defence. (you will be given more points on the more you know.)
• The foreign body (bacteria, virus etc) has Antigens on its surface. Antigens are large protein molecules that act as an ID tag for the invader. There are billions of different antigens
• Our B-cells, recognize specific antigens. There is a different B Cell for every antigen. We make about 100,000,000 B cells every 3 days, they only live 2-3 days
• IF and WHEN the antigen has been recognized by a B-Cell, the B-Cell produces Antibodies. The B- Cell wears the Ab’s on its surface (Y shaped particles) The Ab’s stick to the antigens on the surface of the invader. (lock and key) All of the Ab’s then group together. Each antibody, which is stuck to a BCell, holds onto an antigen so big clumps form
• Then come the macrophages. These are huge white blood cells that eat things. They eat the Ab-Ag clumps
• Once they eat the clumps, they display the proteins of the antigens on their surface. After eating, the macrophages release enzymes that destroy themselves and the bad guys (suicide mission!) Whole bunch of macrophages=pus
• T-CELLS, receive messages from macrophages about the specific antigen they have eaten. This stimulates the T-Cells to divide and differentiate into other types of TCellsHelper T and Killer T
• Helper T’s send messages to B Cells, telling them to divide and make more of the Ab that was used to catch the bad guys
• More BCells and Ab’s are made, the antibodies grab more antigens, more macrophages see them and they get eaten….this continues=positive feedback
• Killer T’s run out and kill more envaders