Which of the following correctly describes the process of inspiration (air entering the lungs).

A. The lungs expand, causing their internal pressure to decrease

B. The lungs expand, causing their internal pressure to increase

C. The lungs contract, causing their internal pressure to increase

D. The lungs contract, causing their internal pressure to decrease

The process of inspiration involves the  lungs expanding , causing the

internal pressure to decrease.

Inspiration involves the process in which oxygen is inhaled and taken into

the body through the nostrils.  This process brings about the rib cage

being expanded which also affects the lungs.

The lungs which have been expanded brings about a decrease in the

internal pressure as a result of it exerting a lesser force on the internal

system as a result of the oxygen present in it.

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The lungs expand, causing their internal pressure to decrease.

Explanation:

Inhalation is one of the two mechanisms of breathing when air or oxygen is taken in.

During the process of inhalation or inspiration when air is inhaled  following changes occur:

Diaphragm gets contracted and pulls to downward attaining convex shape and the muscles in between rib ( intercostal muscles) get contracted and gets upward pull attaining the concave shape.

This contraction causes the lungs to expand and the air pressure with in gets decreased in comparison to atmospheric pressure. This results in inhalation of air into the lungs.