Communicable Disease Flashcards
How do viruses damage the tissues of their host organism?
Viruses take over the cell metabolism. The viral genetic material gets into the host cell and is inserted into the host DNA. The virus uses the host cell to make new viruses which then burst out of the cell, destroying it and then spread to infect other cells.
How do protoctista damage the tissues of their host organism?
Some protoctista also take over cells and break them open as the new generation emerge, but they do not take over the genetic material of the cell. They simply digest and use the cell contents as they reproduce. Protoctista which cause malaria are an example of this.
How do fungi damage the tissues of their host organism?
Fungi digest living cells and destroy them. This combined with the response of the body to the damage caused by the fungus gives the symptoms of disease.
What type of lymphocytes are involved in cell-mediated immunity?
T-lymphocytes
What is the purpose of cell-mediated immunity?
- To respond to cells of an organism that have been changed in some way e.g by viral infection or mutation (cancer).
What is the first step of CMI?
- Macrophages engulf and digest pathogens by phagocytosis, using the MHC to process and present antigens, becoming APCs.
What happens after macrophages engulf antigens and become APCs? (Step 2)
- The receptors on some of the T helper cells fit the antigens. These become activated and produce interleukins, which stimulate more T cells to divide rapidly by mitosis. They form clones of identical activated T helper cells that all carry the right antigen to bind to a particular pathogen.
What happens after the T helper cells are activated and cloned? (Step 3)
- The cloned T cells can: develop into T memory cells; produce interleukins that stimulate phagocytosis; produce interleukins that stimulate B cells to divide; stimulate the development of a clone of T killer cells that are specific for the presented antigen and then destroy infected cells.
