why do we yawn?
where can i get the website for Oxford "College" located at Scarborough Town Centre?
Answers:
THE TRUTH IS that we don’t completely understand why people, or animals for that matter, yawn.
It’s widely assumed that yawning occurs because we are tired or bored or because we see someone else doing it, but there isn’t any hard evidence to support these beliefs.
Scientists do not purport to know all of the biological mechanisms of the yawn, but tend to agree that a yawn is an involuntary respiratory reflex, which regulates the carbon dioxide and oxygen levels in the blood.
Technically, a yawn is the reflex opening of the mouth followed by the deep inhalation and slow exhalation of oxygen.
The very act of yawning is but one of a number of involuntary reflexes controlled by the spinal and nerve centers.
Scientists speculate that the onset of a yawn is triggered either by fatigue, or by sheer boredom as, at those times, breathing is shallow, and little oxygen is carried to the lungs by the oxygen-toting cardiovascular system.
When one yawns, his or her alertness is heightened, as the sudden intake of oxygen increases the heart rate, rids the lungs and the bloodstream of the carbon dioxide buildup, and forces oxygen through blood vessels in the brain, while restoring normal breathing and ventilating the lungs.
This quite plausible theory of yawning falls short of explaining many aspects of yawning. Scientists explain away the "contagious" nature of yawning, that is when one person's yawn triggers another nearby to yawn, as due to the power of suggestion, but are at a loss when attempting to explain why yawning occurs excessively in patients with lower brainstem damage or with multiple sclerosis.
Other unlocked mysteries include why fetuses in the womb yawn, when it is a well-known fact that they do not intake oxygen into their lungs until after live birth, or why individuals with high concentrations of oxygen in their blood streams yawn.
Until these questions are answered, do not assume that a person who yawns in your presence is bored with what you are saying, or suffers from exhaustion. Simply be pleased that he or she is not bored to death.
Other Answers:
cause we're tired
Why does it happen? Hell if I know but the thing where yawning is contagious, is true. Lions do it as well. Once the Alpha male lion yawns, all the rest of the lions yawn. Allegedly has osmehting to do with dominance in a species or social group.. take it for what you want.
Source(s):
http://faculty.washington.edu/chudler/yawning.html
Why am i growing unwanted hair inbetween my brest?
dehydration usually. Drink more water. Really works.Causes of yawning
A long-standing hypothesis is that yawning is caused by an excess of carbon dioxide and lack of oxygen in the blood. The brain stem detects this and triggers the yawn reflex. The mouth stretches wide and the lungs inhale deeply, bringing oxygen into the lungs and hence to the bloodstream. It is almost certain however, that this hypothesis is not correct; a more recent hypothesis is that yawning is used for regulation of body temperature. Another hypothesis is that yawns are caused by the same chemicals (neurotransmitters) in the brain that affect emotions, mood, appetite and other phenomena. These chemicals include serotonin, dopamine, glutamic acid and nitric oxide. As more of these compounds are activated in the brain, the frequency of yawning increases. Conversely, a greater presence in the brain of opiate neurotransmitters such as endorphins, reduces the frequency of yawning. Patients taking the serotonin reuptake inhibitor Paxil (Paroxetine HCl) have been observed yawning abnormally often.
Another theory is that yawning is similar to stretching. Yawning, like stretching, increases blood pressure and heart rate and also flexes many muscles and joints. Some have observed that if you try to stifle or prevent a yawn by clenching your jaws shut, the yawn is unsatisfying. As such, the stretching of jaw and face muscles seems to be necessary for a good yawn.
Source(s):
http://www.answers.com/topic/yawn?gwp=19
Why do you have to turn your head and cough? What are doctors looking (feeling) for?
I hope that Manu answered your question in detail.We yawn because the body needs extra oxygen, plain and simple.
My best friend sums it up in agreement with previous answers, 'the brain needs more oxygen'.
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