Which one of the following is a possibility for most of us with regards to breathing, by making a conscious effort?
(a)One can consciously breathe in and breathe out by moving the diaphragm alone, without moving the ribs at all
(b)The lungs can be made fully empty by forcefully breathing out all air from them.
(c)One can breathe out air totally without oxygen.
(d)One can breathe out air through the eustachian tube by closing both the nose and the mouth

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Hint: Forceful exhalation with closed mouth and nose tends to unclog a partially blocked and the effects are immediately felt. Variations of the maneuver are often used either within the checkup as a test of cardiac function and autonomic nervous control of the guts, or to clear the ears furthermore, sinuses, when encompassing weight changes, as in jumping, hyperbaric oxygen treatment, or avionics.

Complete answer:
During breathing, 20% oxygen is taken in and 15% oxygen is exhaled out. The movement of the diaphragm is very important during the breathing process. Ribs also will move in and out with the diaphragm. It is impossible to breathe by moving the diaphragm along without moving ribs. Even after intense exhalation, lungs are rarely completely discharged. Residual volume, that is the base measure of air in the lungs constantly stays consistently. The eustachian tube associates the center ear depression with the nasopharynx and thus, one can inhale out air through it by shutting both nose and mouth.

Additional information:
An altered rendition is finished by terminating against a shut glottis. This will evoke the cardiovascular reactions portrayed underneath yet won't drive air into the Eustachian tubes.
The normal physiological response consists of four phases.
Initial pressure rise
On the appliance of expiratory force, pressure rises inside the chest forcing blood out of the circulation into the left atrium of the heart. This causes a slight rise in stroke volume during the primary few seconds of the maneuver.
Reduced venous return and compensation
The return of systemic blood to the guts is impeded by the pressure inside the chest. The output of the guts is reduced and stroke volume falls. This occurs from 5 to about 14 seconds within the illustration. The fall in stroke volume reflexively causes blood vessels to constrict with some rise in pressure (15 to twenty seconds).
Pressure release
The pressure on the chest is delivered, permitting the pneumonic vessels and accordingly the aorta to re-grow causing an additional underlying slight fall in stroke volume (20 to 23 seconds) because of diminished left atrial return and expanded aortic volume, individually.
Return of cardiac output
Blood return to the guts is enhanced by the effect of entry of blood which had been dammed back, causing a rapid increase in flow (24 seconds on).

So the correct answer is ‘One can breathe out air through the eustachian tube by closing both the nose and the mouth’.

Note: Exhalation of the air by the powerful closure of mouth and nose prompts the air going through the Eustachian tube bringing about air circulation of the middle ear cavity. This technique is known as the Valsalva maneuver. Generally, it is done by shutting one's mouth, squeezing one's nose shut while squeezing out as though exploding an inflatable.