What role do intercostal muscles play in respiration?

Intercostal muscles are essential during respiration because they facilitate the expansion and contraction of the chest cavity. These muscles are located between the ribs and are responsible for adjusting the volume of the thoracic cavity during the breathing process. When the intercostal muscles contract, they elevate the ribs, which increases the volume of the chest cavity and helps draw air into the lungs (inhalation). Conversely, during exhalation, the muscles relax, allowing the ribs to move back to their resting position, which decreases the volume of the chest cavity and pushes air out of the lungs. This mechanical action is critical for effective ventilation and is the reason why the described role in the expansion and contraction of the chest is integral to the respiratory process.

The other options relate to physiological functions that do not directly involve the mechanics of breathing. For instance, metabolic rate pertains to the energy expenditure and biochemical processes of the body, while digestive enzyme secretion is related to the digestive system. Blood pressure regulation is primarily managed by the circulatory system, making them less relevant to the specific role of intercostal muscles in respiration.