eli5: what exactly happens when we cough and what causes the sound?
In: Biology
When we cough, your lungs rapidly contract and force the air out.while the sound comes from the rapid burst of air through your vocal tract followed by it suddenly closing.
Respiratory therapy student here! There are technically 4 stages that take part when a person coughs. I hope this isn’t confusing!
1 Irritation- sensory fibers are stimulated(a sensory fiber is a tiny thin nerve shaped like a hair. In this case one of the sensory fibers is located in the trachea) this can be stimulated by inhaling a chemical like bleach – say you’re cleaning your sink or something! Well, so that sends an impulse to the vagus nerve (a nerve that runs from your neck to your abdomen) to the medulla (part of the brain that helps control involuntary functions like sneezing!)
2 Inspiration- (breath in) an average person usually inhales 1-2 liters of air as a reaction to the stimulation. This inhalation happens so that a person can generate enough air to actually perform a cough
3 Compression – this is when the glottis closes, the muscles of the chest walls contract, the diaphragm contracts, and the muscles of the abdominal wall contract too.
4 Expulsion- the glottis (the glottis is the flap that’s a part of the throat. The glottis helps protect you from food going into the larynx, the vocal cords are also found here!) that opens and this results in a large expiratory (breath out) flow. This is also the phase of the cough when the cough makes the sound. the sound is caused by air that vibrates through the vocal cords. The sound is also a cause of any mucus coming up through the lungs to the throat
I know this is long, but basically what happens is something irritates nerves in your throat, this sends a message to your brain that something foreign is entering your body! So your body will naturally, involuntarily take a big inhale, then your glottis will close, your muscles will contract, then your glottis opens and you exhale. Sometimes, say if you’re sick and you have mucus it’ll come up and out, this can make a crackling sound. If nothing comes up and out, basically the air that you’re exhaling is vibrating the vocal cords and that vibration makes a sound!
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