Question

During normal resting breathing, exhalation is associated with: group of answer choices

O the pressure in the lungs increasing above atmospheric pressure.
O air which is high in carbon monoxide moving out of the lungs.
O oxygen moving against its partial pressure gradient.
O the diaphragm contracting and moving downward to decrease the pulmonary pressure.

Answer 1

During normal resting breathing, exhalation occurs as the diaphragm relaxes, and lung pressure increases above atmospheric pressure, forcing air out in a passive process. The answer is option A.

Step-by-step explanation:

During normal resting breathing, exhalation is associated with the pressure in the lungs increasing above atmospheric pressure. This occurs because as the diaphragm relaxes, it moves upwards and decreases the volume of the thorax, which increases the air pressure inside the lungs compared with the external atmosphere.

Consequently, air is forced out of the lungs, similar to how air is released from a balloon. This part of the breathing cycle is typically a passive process and does not require energy as it mainly relies on the elasticity of the lungs and the relaxation of the diaphragm and intercostal muscles.