What is the correct path a molecule of O2 takes from the nose to the respiratory surface in the lungs?

• A. Nose → Pharynx → Larynx → Trachea → Bronchi → Bronchioles → Alveoli
• B. Nose → Trachea → Larynx → Pharynx → Bronchi → Bronchioles → Alveoli
• C. Nose → Larynx → Pharynx → Trachea → Bronchioles → Bronchi → Alveoli
• D. Nose → Bronchi → Trachea → Larynx → Pharynx → Bronchioles → Alveoli

Answer: (A)

Verified step by step guidance

1. Begin by understanding the anatomy of the respiratory system and the sequence of structures that air passes through from the external environment to the lungs.
2. The first step in the pathway is the nose, where air enters the respiratory system. The nose filters, warms, and humidifies the air.
3. Next, the air moves to the pharynx, a muscular tube that serves as a pathway for both air and food.
4. From the pharynx, the air travels to the larynx, which is also known as the voice box. The larynx is responsible for sound production and also protects the trachea against food aspiration.
5. After the larynx, the air enters the trachea, a tube that connects the larynx to the bronchi. The trachea splits into two bronchi, each leading to one lung, and the pathway continues through the bronchi, bronchioles, and finally reaches the alveoli, where gas exchange occurs.