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Hey Rich and Bob,
I'm just doing the revision questions in CHUF E-text (Revision test no.1) and came along this little beauty of a question.
Q No 33)
During a descent with blocked Eustachian Tubes, The gas volume in the middle ear?
a.increases
b.decreases
c.remain constant
I strongly feel as if the answer should be C
Would you be so kind as to advise why the answer is B?
Kind regard,
Chris
The eustachian tube provides a vent to allow air to flow either into or out of the middle ear cavity. When it is blocked (by mucus during a heavy cold) any air within the cavity is trapped in that space. If you have been flying at high altitude, that air will be the same pressure as the outside air (assuming you are not pressurised). During descent, the pressure on the outside of the eardrum increases and, since the eardrum is flexible, it begins to bulge inwards. This decreases the effective volume of the middle ear cavity. The stretching of the eardrum causes pain.
[attachment=804]Descending.png[/attachment]