How Yawn Occurs?
A yawn is a reflex consisting of the simultaneous inhalation of air and the stretching of the eardrums, followed by an exhalation of breath. Yawning (oscitation) most often occurs in adults immediately before and after sleep, during tedious activites and as a result of it’s contagious quality. It is commonly associated with tiredness, stress, sleepiness, or boredom and hunger.
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| Two tigers are yawning |
A yawn is a coordinated movement of the thoracic muscles in the chest, diaphragm, larynx in the throat, and palate in the mouth. By yawning, we help distribute surfactant (wetting agent) to coat the alveoli (tiny air sacs) in the lungs. Generally, we can not yawn on command. It is theorized that yawning is a semi-voluntary action and partly a reflex controlled by neurotransmitters in the hypothalamus of the brain. It is also associated with increased levels of neurotransmitters, neuropeptide proteins and certain hormones.
That is how yawn occurs.
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