National League for Nursing (NLN) Science Practice Exam

What is the process by which oxygen travels from the air into your lungs and then into your blood?

1. Hypertonic

2. Osmosis

3. Diffusion

4. Passive transport

The correct answer is: Diffusion

The process by which oxygen travels from the air into the lungs and then into the blood is described as diffusion. Diffusion is the movement of molecules from an area of higher concentration to an area of lower concentration. In the lungs, the concentration of oxygen in the alveoli (tiny air sacs) is higher than in the blood vessels surrounding them. Therefore, oxygen naturally moves across the thin walls of the alveoli into the blood, where its concentration is lower. This passive movement continues until there is an equal concentration of oxygen, allowing for efficient gas exchange necessary for respiration and cellular function. While passive transport refers to the movement of substances across cell membranes without the need for energy, it is a broader term that includes various mechanisms, including diffusion. However, the specific mechanism by which oxygen moves from the air into the blood is diffusion. Osmosis, which is the movement of water across a semipermeable membrane, is not relevant in this context since it specifically pertains to water molecules rather than gases like oxygen. Hypertonic refers to a solution with a higher concentration of solutes compared to another solution, which does not accurately describe the movement of oxygen in this situation.