2006-09-15 12:22:33 · 4 answers · asked by Renee T 1 in Science & Mathematics ➔ Other - Science
Lack of oxygen
2006-09-15 12:37:28 · answer #1 · answered by Jewel 2 · 0⤊ 0⤋
People usually yawn when they are tired or bored or due to the lack of oxygen. There has been many theories that are out there in the Net, but mostly it is known to be a reflex action to the lack of oxygen.
When carbon dioxide levels in the blood increase due to an increase in respiration, chemoreceptors in the body detect such a change and causes it to respond by sending signals to the diaphragm for inhalation to take place, thus causing yawns and a large intake of oxygen for the body to function.
hope this helps! :)
2006-09-15 16:55:58 · answer #2 · answered by musicalif3 2 · 1⤊ 0⤋
Yawns are a reaction to having too much carbon dioxide in your blood stream. There are receptors in your brain that sense this higher amount of CO2. You brain then will cause you to yawn.
2006-09-15 12:26:12 · answer #3 · answered by Mr. G 6 · 0⤊ 0⤋
Lack of oxygen in the bloodstream, so as a reflex you yawn
2006-09-15 12:26:22 · answer #4 · answered by Anonymous · 0⤊ 0⤋