Which components are primarily involved in the respiratory system?

The primary components involved in the respiratory system are the lungs and the related muscles. The lungs facilitate the exchange of gases—oxygen and carbon dioxide—between the air and the bloodstream. They play a vital role in the process of breathing, which includes inhalation and exhalation.

Inhalation involves the contraction of the diaphragm and the intercostal muscles, which expands the thoracic cavity and allows air to flow into the lungs. During exhalation, these muscles relax, causing the thoracic cavity to shrink and pushing air out of the lungs. This coordinated activity is essential for proper respiratory function.

Other options focus on components that are not primarily about respiration. The heart and arteries pertain more to the circulatory system, which is responsible for transporting blood throughout the body. Veins and capillaries are also part of the circulatory system, aiding in the return of blood to the heart and facilitating nutrient and gas exchange in tissues. Alveoli are crucial for gas exchange, but platelets are involved in blood clotting rather than respiration. Thus, the correct answer highlights the core elements of the respiratory system, specifically the lungs and the associated muscles that enable breathing.