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specific/non specific immunity (strand 2) - Coggle Diagram
specific/non specific immunity (strand 2)
specific immunity (controlled by two types of lymphocytes)
T lymphocytes (T cells) ~ mature in the thymus, involved in cell mediated immunity
B lymphocytes (B cells) ~ mature in the bone marrow, involved in humoral immunity
cell mediated immunity
lymphocytes respond to cells with non - self antigens on their surface and not antigens in fluids producing the cellular response
cells that display foreign antigens on their surface are called antigen presenting cells
method (cell mediated immunity)
pathogens invade body cells or are taken in by phagocytes.
the phagocyte or invaded body cell displays the pathogen antigens on its cell surface membrane
receptors on the specific T helper cells are complementary to the antigens so they can bind to them
the T cell divides due to mitosis to produce genetically identical cells
the cloned cells can then either: develop into memory cells, stimulate phagocytes, stimulate B lymphocytes (B cells) or activate cytotoxic T cells to produce perforin
humoral immunity
B cell finds complementary antigen in bodily fluids
B cells antibodies bind to the complementary antigen
the antigen enters the B cell by endocytosis and is then presented on its surface
T helper cells bind to the antigen and stimulate B cell division by mitosis to produce identical cells called clonal selection
each clone produces one specific type of antibody and lots of them, this means that the antibodies are referred to as monoclonal antibodies
phagocytosis
chemical products of pathogens or dead, damaged and abnormal cells act as attractants causing phagocytes to move towards the pathogen e.g. a bacterium
phagocytes have several receptors on their cell surface membrane that recognise, and attach to chemicals on the surface of the pathogen
they engulf the pathogen to form a vesicle known as a phagosome
lysosomes move towards the vesicle and fuse with it
enzymes called lysozymes are present within the lysosome. these lysozymes destroy ingested bacteria by hydrolysis of their cell walls. the process is the same as that for the digestion of food in the intestines, namely the hydrolysis of larger, insoluble molecules, into smaller, soluble ones
the soluble products from the breakdown of the pathogen are absorbed into the cytoplasm of the phagocyte