What is the active component of respiration?

The correct choice, inspiration, is considered the active component of respiration because it involves the muscular effort required to inhale air into the lungs. During inspiration, the diaphragm and intercostal muscles contract, leading to a decrease in intrathoracic pressure, which allows air to flow into the lungs. This process requires energy and muscle activity, distinguishing it from other components of respiration.

Exhalation, in contrast, is often a passive process that occurs when the diaphragm and intercostal muscles relax, allowing the lungs to deflate and air to escape without significant muscular effort. Ventilation encompasses both inhalation and exhalation as a complete process of moving air in and out of the lungs but does not specify which phase is active. Diffusion refers to the movement of oxygen and carbon dioxide across the alveolar membrane and into the blood, which is a separate physiological process not classified as an active component of respiration itself.