What happens during exhalation?

During exhalation, the primary function is the expulsion of carbon dioxide from the lungs. This process occurs as the diaphragm and the intercostal muscles relax after inhalation, decreasing the thoracic cavity's volume and increasing the pressure inside the lungs. This pressure change forces the air, which is rich in carbon dioxide (a waste product of cellular metabolism), out of the lungs and into the environment. The removal of carbon dioxide is essential for maintaining the body's acid-base balance and ensuring that oxygen can be efficiently utilized in the body.

In contrast, inhalation, which is about taking in air, involves the intake of oxygen, not the expulsion of carbon dioxide. The absorption of oxygen into the bloodstream occurs during inhalation, as gases diffuse across the alveolar membrane. Finally, food passing from the stomach to the intestines is unrelated to the respiratory system and pertains to the digestive system, highlighting the specificity of physiological processes in different body systems.