ANIMAL PHYSIOLOGY
GAS EXCHANGE IN HUMANS
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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The lungs expand to push the ribs upwards.
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The entry of air causes the lungs to expand.
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The air pressure inside the lungs keeps decreasing during inhalation.
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The contraction of the diaphragm muscles causes the lungs to expand.
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Detailed explanation-1: -Explanation: When the chest expands air enters the lungs. This is because during inspiration the diaphragm contracts and moves downwards. This leads to an increase in the chest cavity, with the help of the intercostal muscles present between the ribs.
Detailed explanation-2: -Upon inhalation, the diaphragm contracts and flattens and the chest cavity enlarges. This contraction creates a vacuum, which pulls air into the lungs. Upon exhalation, the diaphragm relaxes and returns to its domelike shape, and air is forced out of the lungs.
Detailed explanation-3: -When you breathe in, or inhale, your diaphragm contracts and moves downward. This increases the space in your chest cavity, and your lungs expand into it. The muscles between your ribs also help enlarge the chest cavity. They contract to pull your rib cage both upward and outward when you inhale.
Detailed explanation-4: -Contraction of the diaphragm reduces pulmonary volume and increases intrapulmonary pressure causing expiration.
Detailed explanation-5: -Contraction of the diaphragm increases the internal height of the thoracic cavity, thus lowering its internal pressure and causing inspiration of air.