question_answer

   (a) Name two airborne diseases. How does the disease causing microbes spread through air? (b) How does HIV virus spread from a patient to healthy person? (c) How does the immune system of our body function?                      [CBSE2010]

Answer:

 (a) Pneumonia and common cold are two airborne diseases. Spreading of disease-causing microbes occurs through the little droplets thrown out by an infected person who sneezes or coughs. Someone standing close by can breathe in these droplets and microbes get a chance to start new infection.                   (b) HIV virus (AIDS) spread among human beings by following ways (i) Through transfusion of blood contaminated with HIV virus. (ii) Infected mother can transmit the virus to her child during pregnancy or during birth. (ii) Through sexual contact with an infected person.                                (c) When infectious microbes enter into our body, then body's immune system get activated in response to infection. An active immune system recruits many cells to the affected tissue to kill off the disease causing microbes. This recruitment process is called inflammation and it produces pain, fever, swelling as a part of this process,