What happened when the intrapulmonary pressure is less than atmospheric pressure ?

What atmospheric pressure ?

Read the following statement (A - D). (A) The movement of air into and out of the lungs is carried out by creating a pressure gradient between the lungs and atmosphere. (B) Inspiration can occur if the pressure within the lungs is more than the atmospheric pressure. (C) Expiration takes place when the intrapulmonary pressure is lesser than the atmospheric pressure. (D) The diaphragm and a specialized set of intercostal muscles in between the ribs help in the generation of such pressure gradients for breathing. How many of the following statements are correct?

What is atmospheric pressure?

What is atmospheric pressure ?

What is atmospheric pressure ?

A decrease in intrapulmonary pressure to less than atmospheric pressure causes

A decrease in intrapulmonary pressure to less than atmospheric pressure causes