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Choose the incorrect statement

 

Option: 1

Human lungs are negative pressure lungs.

 

 

 


Option: 2

Inspiration occurs if the pressure within the lungs is more than the atmospheric pressure

 


Option: 3

During inspiration, diaphragm contracts to expand thoracic cavity 

 


Option: 4

The movement of air into and out of the lungs is carried out by creating a pressure gradient between the lungs and the atmosphere.

 


Answers (1)

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Mechanism of Breathing: Inspiration -

 
  • The movement of air into and out of the lungs is carried out by creating a pressure gradient between the lungs and the atmosphere.
  • Human lungs are negative pressure lungs.
  • Inspiration can occur if the pressure within the lungs (intrapulmonary pressure) is less than the atmospheric pressure, i.e., there is a negative pressure in the lungs with respect to atmospheric pressure. 
  • The diaphragm and a specialised set of muscles – external and internal intercostals between the ribs, help in generation of such gradients.
  • Inspiration is initiated by the contraction of diaphragm which increases the volume of the thoracic chamber in the anteroposterior axis. 
  • The contraction of external intercostal muscles lifts up the ribs and the sternum causing an increase in the volume of the thoracic chamber in the dorso-ventral axis.
  • The overall increase in the thoracic volume causes a similar increase in pulmonary volume.
  • An increase in pulmonary volume decreases the intrapulmonary pressure to less than the atmospheric pressure which forces the air from outside to move into the lungs, i.e., inspiration. 

Hence the correct option is Inspiration occurs if the pressure within the lungs is more than the atmospheric pressure

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Gaurav

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