✔ 最佳答案
1.how bacteria can enter the body?Ans: The bacteria ,Salmonella, are still in beef. They enter our body via gastrointestinal system (i.e. via our mouth and oesophagus and then reach out stomach and intestine). Once they reach the destination, they will pass through the mucosa of the gastrointestinal organs and produce fatal toxins.
2. Which barriers the bacteria must overcome when entering the body? Ans: The chemical barrier in our stomach which produces hydrochloric acid by oxyntic cells of the stomach and also the mechanical layer, the mucosa layer of the intestinal and stomach tissue.
3.How the bacteria reproduce in the digestive system?Ans: By binary fission if they are asexual ones. If they contain DNA or RNA , transformation and transduction can be carried out for reproducing themselves in the digestive system .
4.What the body can do to fight the infection? Ans: Trigger macrophages to engulf the bacteria. Besides, the macrophages will release interleukin 1, IL-1 which will trigger the T helper cells. T helper cells then release, IL-2 , IL-4 and interferon gamma, IFN-gamma, which will mobilize the B cells, a kind of white blood cell. B cells will then differentiate into plasma cell, an antibody producing cell, which will form antibody to act against the bacteria.
5.How the body can prepare itself for a future infection from the same bacteria?Ans: In our body, for those B cells without turning out to be the antibody producing cells (plasma cell) will become memory cells which will produce IgG, a kind of antibody, to act against the same bacteria. For these T helper cells in our body, some of them also become memory cells after the battle. The will call macrophage for help to trigger the B cells and make macrophage to engulf the same bacteria in future infection. This is called secondary response.
I hope you will find them helpful.
2007-11-23 17:26:55 補充：
macro*****es = macro + phages
2007-11-23 17:28:31 補充：
印不到巨噬細胞一子即marco+ph+age+es
