Adaptive Immune system

What are the characteristics of the Adaptive Immune System?

it targets unique antigens on specific pathogens, it creates memory cells, it has a delayed response and could take days or weeks to fully activate upon first exposure

What is the role of Helper T cells in the adaptive immune response?

they act as the directors of the adaptive immune system. they recognise MHC II markers on APCs and then release cytokines that stimulate clonal selection and expansion in both B cells and cytotoxic T cells

What is the humoral immune system?

the part of the adaptive immune system that protects the body from extracellular pathogens like bacteria and toxins. B cells differentiate into plasma cells which secrete antibodies and memory B cells for long term immunity

What is the structure of an antibody?

a y shaped quaternary protein made of four polypeptide chains. it has a constant region and two highly specific variable region that fit prefectly with a specific antigen

How do antibodies destroy pathogens (4 ways- can occur simultaneously)

agglutination is where pathogens become trapped in a network of antibodies making them immobile and susceptible to phagocytosis. opsonisation is where an antibody binds to pathogen acting as a ‘tag’ so that phagocytes can locate them. neutralisation is where antibodies block antigens from binding to other targets. complement activation is where antibodies activate the complement cascade

What is the Cell mediated response?

the part of the adaptive immune system that protets the body from intracellular pathogens such as virus and cancer

How do Cytotoxic T cells destroy infected cells?

they scan the body for foreign antigens presented on MHC I markers and bond to the cell where they release perforin and granzymes to induce apoptosis

What is the role of Memory T cells?

they retain memory of the specific antigen so that upon re-exposure they turn into helper to cells and cytotoxic T cells to eliminate the internal threat faster

What is Clonal Selection?

inside the lymph nodes a helper T cell with a T cell receptor that is perfectly complementary to the antigen binds to the APC

What is clonal expansion?

once bound, helper T cell is activated and undergoes mitosis to create identical clones, these release cytokines to activate specific B cells and cytotoxic T cells