11.   Death of amoebae within the lower respiratory tract would result in the release of large numbers of bacteria at a temperature that favours their rapid multiplication.

12.   Also, with the flu, the lower respiratory tract is commonly attacked by the culprit virus, leaving the bronchial tubes wracked with a hacking cough.

13.   Because influenza is caused by viruses that infect the respiratory tract, antibiotics are not an effective treatment.

14.   - Influenza, commonly called flu, is caused by viruses that infect the respiratory tract.

15.   After each exposure to pollen proteins, allergy-prone individuals form antibodies that attach themselves to mast cells in the mucous membranes of the upper respiratory tract.

16.   But in rare cases a virulent strain of N. meningitidis manages to penetrate mucosal cells in our respiratory tract.

17.   But the infection can then move into the lower respiratory tract -- the bronchioles and lungs.

18.   By inhibiting the action of neuraminidase, the drug halts reproduction and stops the virus from infecting other cells in the respiratory tract, they said.

19.   From reconstructions of their upper respiratory tract, he has proposed that the Neanderthal larynx was higher up in the throat than it is in modern humans.

20.   Infected mucus then drips into the lower respiratory tract, triggering bronchitis and asthma.