Cough is also known as tussis is a path for body to protects lungs of humans and animals, when mucus find in the airways with deposited dust particles isn't cleared effectively enough by the usual ciliary motions the upper airway linings do all the time to keep the airways clear or I can say A cough is a reflex action to clear the airways of irritants such as smoke, dust or mucus. It can be either voluntary or involuntary and is mechanism involving the brain, diaphragm and lungs,
3 Phases of cough.
1. Inhalation (breathing in)
2. Increased pressure in throat and lungs with vocal chords closed
3. Vocal chords open and allow an explosive release of air, which gives the cough its sound.
Reasons of coughing.
Physiologic/pathologic. You normally produce mucus down in your airway and then finger-like projections of ciliated cells waft it upwards. It's how you trap and get rid of the usual clutter of dust particles and various microbes you breathe in. Most people just end up swallowing this normal quantity of mucus with the occasional throat-clearing, but if you're producing excess, such as in times of illness or other irritation (e.g. cigarette smoke, heavy pollution, etc.), then coughing it up is a pretty common way to clear this extra mess from your system.
Foreign objects: Coughing is one method of attempting to dislodge something that is choking someone. Given that you generate the equivalent of a wind >100 mph with a powerful cough, it's often effective.
· Liquid: Normally, liquid just flows around the airway hole on its way down to the stomach. If it goes down the wrong chute somehow, then you want to clear it. Coughing works great for this.
Infection: Whooping cough is one of the worse ones, particularly for people who for whatever reason don't get vaccinated. The bacteria's toxin causes systemic irritation and a notoriously long period of dry coughing long after the bacteria itself is wiped from the body. Of course, there are the more common diseases like colds too.
Social clue: Often used to get attention or express discomfort.