Stimulus stimulate the sodium ion voltage gated channel to open in the axon. This allow many Na ion to enter the axon and causes depolarisation as the pd in the axon getting less negative charge (from -70mV to -50mV).
Air moves into the lungs when the air pressure in the lungs is lower than the air pressure outside of the lungs. This occurs when the muscels of the diaphragm contract.
You can see this by breathing in and out deeply. When you breath in you can feel your chest being pushed up and out by your diaphragm. The reason the pressure in the chest is lower is that when you breathe in you are increasing the volume of your chest. As there is the same amount of air in your chest the pressure decreases.
The Answer Is On This Link https://technet.microsoft.com/en-us/library/cc961723.aspx
Water-borne diseases, including cholera, typhoid, and dysentery, are caused by drinking water containing infectious viruses or bacteria, which often come from human or animal waste. Water-washed diseases, such as skin and eye infections, are caused by lack of clean water for washing.
