Given below are two statements.

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

Statement II : Inspiration occurs when there is negative pressure in the lungs with respect to atmospheric pressure.

In light of the above statements, choose the correct answer from the options given below.

Both statement I and statement II are correct.

Statement I: The movement of air into and out of the lungs is indeed facilitated by creating a pressure gradient between the lungs and the atmosphere. During inhalation, the pressure inside the lungs decreases compared to the atmospheric pressure, allowing air to flow into the lungs. During exhalation, the pressure inside the lungs increases compared to the atmospheric pressure, causing air to flow out of the lungs.

Statement II: Inspiration (inhalation) occurs when there is negative pressure in the lungs relative to atmospheric pressure. This negative pressure results from the contraction of the diaphragm and other respiratory muscles, which increases the volume of the thoracic cavity, leading to a decrease in intra-alveolar pressure. Air then flows from the higher atmospheric pressure outside the body into the lower-pressure lungs.