Tag: the mechanism of breathing

Questions Related to the mechanism of breathing

State whether the following statements are true or false.
Forceful expiration results from a forceful contraction of diaphragm.

biology breath and blood of life human respiration the mechanism of breathing breathing and its movements

  1. True

  2. False

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Correct Option: A
Explanation:
  • Forced expiration is an active process. It involves contraction of the abdominal muscles which forces the diaphragm upwards reducing the volume of the thoracic cavity. 
  • It also requires contraction of the internal intercostal muscles and innermost intercostal muscles which pull the ribs downwards. Both these actions contribute to a decreased thoracic volume and pressure is inversely proportional to volume. 
  • Therefore pressure within the lungs increases forcing the air out quicker than in normal expiration.
So, the correct option is 'True'.

Choose the correct answer from the alternatives given.
The respiratory medium flows unidirectionally ever the respiratory surface in the gas-exchange systems of:

biology breath and blood of life human respiration the mechanism of breathing breathing and its movements

  1. mammals

  2. frogs

  3. birds

  4. insects

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Correct Option: C
Explanation:

In birds, the air sacs permit unidirectional flow of air through the lungs. Unidirectional flow means that air moving through bird lungs is largely 'fresh' air & has a higher oxygen content. So, the correct option is 'birds'.

Which of the following is correct

biology breath and blood of life human respiration the mechanism of breathing breathing and its movements

  1. The diaphragm contracts - volume of chest cavity increased

  2. The diaphragm contracts - volume of chest cavity decreased

  3. The diaphragm expands - volume of chest cavity increased

  4. The diaphragm expands - volume of chest cavity decreased

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Correct Option: A