Modified Respiratory Movements

Not every breath follows the ordinary quiet rhythm of inspiration and expiration described above. Some respiratory movements are modified versions of normal breathing, used either to clear irritants and obstructions from the air passage or to express emotion; some of these, like coughing and yawning, can occur as reflexes but can also be triggered voluntarily. Because they use the same muscles as ordinary breathing but in a different pattern or intensity, they are best understood as variations on the basic mechanics of inspiration and expiration covered above, rather than as a separate mechanism. Two recognisable examples, drawn from the chapter's own exercise, are: a spasmodic contraction of the expiratory muscles that forcefully expels air through the nose and mouth at once — this is sneezing, usually triggered by irritation of the nasal lining; and a single inspiration followed by many short, convulsive expirations along with a characteristic facial expression — this describes laughing (a similar convulsive pattern with a different facial expression and cause describes crying/sobbing). Other everyday examples include coughing (a forceful expiration used to clear the lower airway), yawning (a slow, deep inspiration through a wide-open mouth, often linked to drowsiness or a need for more oxygen), hiccupping (an involuntary, …