Final answer:
The trachea is made of C-shaped cartilage allowing it to adjust during breathing; the epiglottis closes over the trachea when swallowing to prevent food from entering the airways. The esophagus expands during swallowing, allowing food passage, facilitated by various mechanisms that ensure the bolus enters the esophagus rather than the trachea.
Step-by-step explanation:
The trachea, also known as the windpipe, is a vital structure in the respiratory system that extends from the larynx toward the lungs. It is comprised of 16 to 20 stacked, C-shaped pieces of hyaline cartilage, connected by dense connective tissue and a fibroelastic membrane. This membrane includes the trachealis muscle, which allows the trachea to stretch and adjust slightly during breathing. When you swallow, the epiglottis, a cartilaginous flap at the top of the trachea, folds down to cover the glottis (the tracheal opening). This mechanism ensures that the esophagus can expand to accommodate food or liquid while simultaneously keeping the trachea clear and protected.
The esophagus runs a straight route through the thorax's mediastinum and enters the abdomen through the esophageal hiatus. It is a muscular tube that remains collapsed when not in use, expanding only during swallowing. As food is swallowed, mechanisms including the rising of the soft palate, contraction of the pharyngeal constrictor muscles, and relaxation of the upper esophageal sphincter work to ensure the bolus enters the esophagus and not the trachea.