third line of defence Flashcards
plasma B cells
responsible for producing antibodies
memory B cells
responsible for long term immunity for future infections
Helper T cells
Responsible for assisting with the activation of other immune cells
cytotoxic T cells
responsible killing virus infected and cancerous cells
MCH I marker
Display self antigens to immune system cells, so that they are recognised as ‘self’ by the immune system. They are recognised by cytotoxic T cells
MCH II marker
activates T helper cells
lymphatic system
consists of blind ended vessels that carry lymph fluid back to the heart
lymphatic organs
bone marrow, thymus, lymph nodes, spleen
Bone marrow and thymus
primary lymphoid organs because they are the sites were lymphocytes (T and B cells) invloved in the third line of defence develop from precursor cells
lymph nodes and spleen
secondary lymphois organs, the sites where mature T and B cells are activated by meeting their complementary antigens and developing int effector cells
B cells
able to recognise foreign antigens, have receptors on their surface called antibodies. Each antibody recognises one antigen
Humoral adaptive immunity
Antigen presenting cells engulf and digest pathogens then display their antigens on their MHC-II markers. They move to the lymph nodes and present these sntigens to the appropriate helper T cells
Clonal selection
The antigen meets a B cell with a complementary shaped antigen binding site;
The B cell engulfs the foreign antigen and displays it on its surface;
Mature activated helper T cells recognise antigen fragments presented by the B cells;
The T helper cells then release cytokines that stimulate the B cells to undergo clonal expansion
Clonal expansion
The B cells differentiate and divide into plasma and memory B cells. The result in. the production of a large clone of B cells all responding to the same antigen. The plasma cells produce and secrete large amounts of antibodies
