Final answer:
The epiglottis separates the upper and lower respiratory tract, with the correct answer to the question being b) Epiglottis. In the journey of inhaled air, it moves through the pharynx, then the larynx, trachea, bronchi, and finally the bronchioles.
Step-by-step explanation:
The structure that separates the upper and lower respiratory tract is the epiglottis. The epiglottis is a flap of cartilage located at the base of the tongue, which closes during swallowing to prevent food from entering the trachea (windpipe). The correct answer to the multiple choice question is b) Epiglottis.
In the sequence of air travel from the pharynx to the bronchioles, air moves through the pharynx, larynx, trachea, bronchi, and then to the bronchioles. The correct order, thus, is c) pharynx → larynx → trachea → bronchi → bronchioles.
Anatomy of the Lower Respiratory System: The lower respiratory system begins below the epiglottis in the larynx or voice box. The trachea is a cartilaginous tube that provides an unobstructed path for air to reach the lungs. It bifurcates into the left and right bronchi, which further branch into bronchioles, culminating in terminal bronchioles that end in alveoli, the site of gas exchange. The human lungs contain approximately 400 million alveoli, each surrounded by capillary networks.