A: The pathway of air goes from the nasal cavity (or oral cavity) to the pharynx to the trachea to the primary bronchi (right and left) to the secondary bronchi to the tertiary bronchi to bronchioles to the alveoli (site of gas exchange)
B: when relaxed, the diaphragm is a dome shape. when we inhale, the diaphragm flattens down, increasing the thorax volume. this reduces the pressure in the thorax, so air moves into the lungs to equalize the pressure. when we exhale the diaphragm moves back into its relaxed dome position.